Method for transmitting / receiving data in wireless communication system and wireless communication terminal

Abstract

To provide a super-high speed wireless LAN service for new multimedia applications.SOLUTION: A method is disclosed in which a multi-link device (MLD) transmits a frame in a wireless communication system. A non-AP MLD can transmit, to an AP MLD, a probe request frame for association, and receive a beacon frame for the association from the AP MLD. Here, a plurality of links are configured for the AP MLD, and the plurality of links are composed of one basic link and at least one extended link, and the beacon frame can be transmitted / received through the basic link.SELECTED DRAWING: Figure 37

Description

[Technical Field]

[0001] The present invention relates to wireless communication systems, and more particularly to a communication method, apparatus, and system for transmitting and receiving frames in multi-link operation including wireless access points that are not capable of simultaneous transmission and reception. [Background technology]

[0002] Recently, as the popularity of mobile devices has increased, wireless LAN technology, which can provide them with high-speed wireless Internet services, has been gaining attention. Wireless LAN technology is a technology that uses short-range wireless communication technology to enable mobile devices such as smartphones, smart pads, laptop PCs, portable multimedia players, embedded devices, etc. to connect to the Internet wirelessly at home, in business, or in specific service areas.

[0003] Since supporting early wireless LAN technology using the 2.4 GHz frequency band, IEEE (Institute of Electronics Engineers) 802.11 has implemented or is currently developing standards for a variety of technologies. First, IEEE 802.11b uses the 2.4 GHz band and supports communication speeds of up to 11 Mbps. IEEE 802.11a, which was commercialized after IEEE 802.11b, uses the 5 GHz band instead of the 2.4 GHz band, reducing the impact of interference compared to the significantly more congested 2.4 GHz band, and uses OFDM technology to improve communication speeds to up to 54 Mbps. However, IEEE 802.11a has the disadvantage of a shorter communication distance than IEEE 802.11b. IEEE 802.11g has attracted considerable attention because it uses the same 2.4GHz band as IEEE 802.11b, achieving a maximum communication speed of 54Mbps and satisfying backward compatibility, but it also has an advantage over IEEE 802.11a in terms of communication distance.

[0004] IEEE 802.11n is a technical standard established to overcome the communication speed limitations that have been identified as a weakness of wireless LANs. IEEE 802.11n aims to increase network speed and reliability and extend the operating distance of wireless networks. Specifically, IEEE 802.11n supports high throughput (HT) of up to 540 Mbps and is based on MIMO (Multiple Inputs and Multiple Outputs) technology, which uses multiple antennas on both the transmitting and receiving ends to minimize transmission errors and optimize data speed. This standard also uses a coding method that transmits multiple duplicate copies to increase data reliability.

[0005] As WLAN adoption continues to grow and applications become more diverse, the need for new WLAN systems is emerging to support data throughput rates (Very High Throughput, VHT) higher than those supported by IEEE 802.11n. Among these, IEEE 802.11ac supports wide bandwidth (80MHz-160MHz) in the 5GHz frequency band. While the IEEE 802.11ac standard is defined only in the 5GHz band, initial 802.11ac chipsets are expected to support operation in the 2.4GHz band as well for backward compatibility with existing 2.4GHz products. Theoretically, this standard enables multi-station WLAN speeds of at least 1Gbps and maximum single-link speeds of at least 500Mbps. This is achieved by expanding the air interface concepts adopted in 802.11n, including wider radio frequency bandwidth (up to 160MHz), more MIMO spatial streams (up to 8), multi-user MIMO, and denser modulation (up to 256QAM). Additionally, there is IEEE 802.11ad, a method of transmitting data using the 60GHz band instead of the conventional 24GHz / 5GHz. IEEE 802.11ad is a transmission standard that uses beamforming technology to provide speeds of up to 7Gbps, making it suitable for streaming large amounts of data and high-bitrate video, such as uncompressed HD video. However, the 60GHz frequency band has the disadvantage of being difficult to pass through obstacles and can only be used between devices in close proximity.

[0006] Meanwhile, the IEEE 802.11ax (High Efficiency WLAN, HEW) standard is being developed and is nearing completion as the successor to 802.11ac and 802.11ad in order to provide high-efficiency and high-performance WLAN communication technology in high-density environments where APs and terminals are densely packed. In an 802.11ax-based WLAN environment, high-frequency-efficient communication must be provided both indoors and outdoors in the presence of a high density of stations and APs (Access Points), and various technologies are being developed to achieve this.

[0007] Additionally, development of new WLAN standards has begun to increase maximum transmission speeds to support new multimedia applications such as high-definition video and real-time gaming. IEEE 802.11be (Extremely High Throughput, EHT), the seventh generation WLAN standard, is currently under development with the goal of supporting transmission rates of up to 30 Gbps through wider bandwidth in the 2.4 / 5 / 6 GHz bands, increased spatial streams, and multi-AP cooperation. IEEE 802.11be proposes technologies such as a 320 MHz bandwidth, multi-link operation, multi-AP (multi-access point) operation, and hybrid automatic repeat request (HARQ) retransmission.

[0008] Multi-link operation operates in various forms depending on its operation method and implementation method. In this case, problems that did not occur in conventional IEEE 802.11-based WLAN communication operations may occur, so a detailed definition of the operation method for multi-link operation is required.

[0009] On the other hand, the art that forms the background of the invention is created to enhance understanding of the background of the invention and includes content that is not prior art already known to those with ordinary skill in the field to which this technology belongs. Summary of the Invention [Problem to be solved by the invention]

[0010] As described above, an object of the present invention is to provide an ultra-high speed wireless LAN service for new multimedia applications.

[0011] Another object of the present invention is to efficiently transmit and receive frames between multi-link devices (MLDs), which are a set of logical entities, when simultaneous transmission and reception is not possible.

[0012] Another object of the present invention is to transmit and receive frames for access only via a specific link formed between MLDs when performing an operation for access (association) between MLDs.

[0013] The technical problems to be achieved in the specification are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those having ordinary skill in the art to which the present invention pertains from the following description. [Means for solving the problem]

[0014] A multi-link device (MLD) of a wireless communication system includes a communication module and a processor that controls the communication module, wherein the processor transmits a probe request frame for access to an AP MLD and receives a beacon frame for the access from the AP MLD, wherein the AP MLD has a plurality of links set up, the plurality of links consisting of one basic link and at least one extended link, and the beacon frame is transmitted and received via the basic link.

[0015] In addition, in the present invention, when the probe request frame is transmitted via the basic link, a probe response frame is received as a response to the probe request frame via the basic link.

[0016] In addition, in the present invention, the beacon frame and the response frame are received only through the basic link, excluding the at least one extension link.

[0017] Also, in the present invention, when the probe request frame is transmitted via the at least one extension link, a probe response frame, which is a response to the probe request frame, is not received via the at least one extension link.

[0018] In addition, in the present invention, the non-AP MLD is composed of a plurality of stations, and one of the plurality of STAs constituting the non-AP MLD forms the basic link with one of the plurality of APs constituting the AP MLD, and the remaining STAs excluding the one STA among the plurality of STAs constituting the non-AP MLD form the at least one extended link with the remaining APs excluding the one AP among the plurality of APs constituting the AP MLD.

[0019] In addition, in the present invention, the AP MLD does not support simultaneous transmission and reception (STR) for the basic link and at least one extended link, and forms the basic link for transmitting a probe response frame and a beacon frame in response to the probe request frame with one STA among a plurality of STAs constituting the non-AP MLD, which is an NSTR soft AP MLD.

[0020] In addition, in the present invention, when the AP MLD operates as an NSTR soft AP MLD, the number of links established by the AP MLD is equal to or less than a specific number.

[0021] In addition, in the present invention, link information regarding links to be established between the AP MLD and the non-AP MLD is received from the AP MLD, and the link information includes at least one of the number of the plurality of links formed between the non-AP MLD and the AP MLD and a bitmap indicating whether each of the plurality of links supports STR operation.

[0022] In addition, in the present invention, a PPDU is transmitted to an AP MLD via the basic link and the at least one extension link, and the transmission start time of the PPDU is the same in the basic link and the at least one extension link.

[0023] The present invention also provides a method including the steps of transmitting a probe request frame for access from an AP MLD and receiving a beacon frame for the access from the AP MLD, wherein a plurality of links are set between the AP MLDs, the plurality of links being composed of one basic link and at least one extended link, and the beacon frame being transmitted and received via the basic link. [Effects of the Invention]

[0024] According to an embodiment of the present invention, multilink information can be signaled efficiently.

[0025] Furthermore, according to the embodiment of the present invention, in a contention-based channel access system, it is possible to increase the overall resource utilization rate and improve the performance of a WLAN system.

[0026] In an AP MLD containing multiple wireless access points (APs), if simultaneous transmission / reception (STR) is not possible for some or all APs, a link capable of STR operation is defined as a basic link, and one of the links incapable of STR is defined as a basic link. The remaining links for which STR is not possible are defined as extended links. A wireless LAN station (STA) not belonging to the MLD is only allowed to access via an STR-enabled link or the basic link. In the case of a STA MLD containing multiple STAs, when accessing the AP MLD, access via the basic link is also allowed when accessing an AP incapable of STR. Therefore, frame transmission via a backoff operation is performed only via the basic link or the link incapable of STR. If the STA MLD detects that another terminal is transmitting frames via the basic link, it exceptionally transmits frames via a backoff operation on an extended link extended from the basic link. After the frame transmission, a simultaneous transmission multiple link operation is performed. By using the corresponding multiple link transmission operation, when performing multiple link simultaneous transmission operation, even if the receiving MLD is unable to perform simultaneous transmission and reception operation, the multiple link communication operation can be performed efficiently, thereby improving communication efficiency.

[0027] The effects obtained from the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those having ordinary skill in the art to which the present invention pertains from the following description. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a diagram showing a wireless LAN system according to an embodiment of the present invention. [Figure 2] FIG. 10 is a diagram showing a wireless LAN system according to another embodiment of the present invention. [Figure 3] FIG. 2 is a diagram showing the configuration of a station according to an embodiment of the present invention. [Figure 4]FIG. 2 is a diagram illustrating a configuration of an access point according to an embodiment of the present invention. [Figure 5] 1 is a diagram illustrating a process in which a STA establishes a link with an AP. [Figure 6] FIG. 1 is a diagram illustrating a CSMA (Carrier Sense Multiple Access) / CA (Collision Avoidance) method used in wireless LAN communication. [Figure 7] 1 shows examples of various standard generation PPDU (PLCP Protocol Data Unit) formats. [Figure 8] 1 illustrates various Extremely High Throughput (EHT) Physical Protocol Data Unit (PPDU) formats and methods for indicating the same according to an embodiment of the present invention. [Figure 9] 1 is a diagram illustrating a multi-link device according to an embodiment of the present invention. [Figure 10] FIG. 10 is a diagram illustrating an example of a TID-to-link mapping method according to an embodiment of the present invention. [Figure 11] FIG. 10 is a diagram illustrating an example of a Multi-link NAV setting operation according to an embodiment of the present invention. [Figure 12] FIG. 10 is a diagram showing another example of a Multi-link NAV setting operation according to an embodiment of the present invention. [Figure 13] FIG. 1 is a diagram illustrating an example of BSS classification and operations based thereon according to an embodiment of the present invention. [Figure 14] FIG. 10 is a diagram illustrating an example of BSS classification based on the U-SIG field according to one embodiment of the present invention. [Figure 15] FIG. 10 is a diagram illustrating an example of BSS classification based on a U-SIG field or an EHT field according to an embodiment of the present invention. [Figure 16] FIG. 10 is a diagram illustrating an example of BSS classification based on MLD addresses according to one embodiment of the present invention. [Figure 17]FIG. 1 is a diagram illustrating an example of how an extended BSS color field is used in accordance with an embodiment of the present invention. [Figure 18] FIG. 10 is a diagram illustrating an example of how an extended TXOP field is used in accordance with one embodiment of the present invention. [Figure 19] FIG. 2 is a diagram illustrating an example of a BSS classification method according to an embodiment of the present invention. [Figure 20] 1 is a diagram illustrating an example of a method for acquiring duration information according to an embodiment of the present invention. [Figure 21] FIG. 1 is a timing diagram illustrating a transmission scheme using multiple links. [Figure 22] 10 is a diagram illustrating an example of a frame transmission and reception process due to unpredictable uplink frame transmission behavior when AP MLD is unable to perform STR. [Figure 23] 10 is a conceptual diagram showing an example of an access state between an AP MLD and a STA or STA MLD using the concept of a basic link when STR is not possible for the AP MLD. [Figure 24] 10 is a conceptual diagram showing an example of an access process between an AP MLD and a STA not belonging to the MLD when STR is not possible for the AP MLD. [Figure 25] 10 is a conceptual diagram illustrating an example of an access process between an AP MLD and a STA MLD when the AP MLD is unable to perform STR. [Figure 26] FIG. 10 is a block diagram illustrating an example of a link indication information element including an indicator indicating a basic link. [Figure 27] 10 is a diagram showing an example of a frame transmission procedure between the AP MLD and the STA MLD using the concept of a basic link when the AP MLD is not capable of STR. [Figure 28] This is a first embodiment showing an operation in which channel access and frame transmission operations are performed exceptionally in an extended link when AP MLD is not possible with STR. [Figure 29]This is a second embodiment showing another example of an operation in which channel access and frame transmission operations are performed exceptionally in an extended link when AP MLD is unable to perform STR. [Figure 30] This is a third embodiment showing another example of an operation in which channel access and frame transmission operations are performed exceptionally in an extended link when AP MLD is unable to perform STR. [Figure 31] This is a fourth embodiment showing yet another example of an operation in which channel access and frame transmission operations are performed exceptionally in an extended link when AP MLD is unable to perform STR. [Figure 32] This is a fifth embodiment showing yet another example of an operation in which channel access and frame transmission operations are performed exceptionally in an extended link when AP MLD is unable to perform STR. [Figure 33] This is a sixth embodiment showing yet another example of an operation in which channel access and frame transmission operations are performed exceptionally in an extended link when AP MLD is unable to perform STR. [Figure 34] This is a seventh embodiment showing yet another example of an operation in which channel access and frame transmission operations are performed exceptionally in an extended link when AP MLD is unable to perform STR. [Figure 35] This is an eighth embodiment showing yet another example of the operation in which channel access and frame transmission operations are performed exceptionally in an extended link when AP MLD is unable to perform STR. [Figure 36] This is an embodiment showing a process of mapping a specific TID to be transmitted from some links by utilizing the concept of a basic link when the AP MLD is unable to perform STR operation. [Figure 37] 1 is a flow chart illustrating an example of a method for access according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] The terms used in this specification are generally used as widely as possible, taking into consideration the functions of the present invention. However, these may vary depending on the intentions of engineers in the relevant technical field, customs, or the emergence of new technologies. In addition, in certain cases, the applicant has arbitrarily selected terms, and in such cases, the meanings thereof will be described in the relevant description of the invention. Therefore, it is made clear that the terms used in this specification should be interpreted not simply as names of terms, but based on the substantive meanings of the terms and the overall content of this specification.

[0030] Throughout this specification, when a component is referred to as being "connected" to another component, this includes not only when the component is "directly connected" to the other component, but also when the component is "electrically connected" to the other component via another component therebetween. Furthermore, when a component is referred to as "comprising" a specific component, this does not mean that the component excludes the other component, but that the component may further include the other component, unless otherwise specified. Additionally, limitations such as "greater than" or "less than" based on a specific critical value may be appropriately substituted with "exceeds" or "less than," respectively, depending on the embodiment. Hereinafter, in the present invention, the terms "field" and "subfield" may be used interchangeably.

[0031] FIG. 1 is a diagram showing a wireless LAN system according to an embodiment of the present invention.

[0032] A wireless LAN system includes one or more Basic Service Sets (BSSs), which are a set of devices that can synchronize and communicate with each other. Generally, BSSs are classified into infrastructure BSSs and independent BSSs (IBSSs), and Figure 1 shows an infrastructure BSS.

[0033] As shown in FIG. 1, the infrastructure BSSs BSS1 and BSS2 include one or more stations STA1, STA2, STA3, STA4, and STA5, access points AP-1 and AP-2 that are stations providing distribution services, and a distribution system DS that connects multiple access points AP-1 and AP-2.

[0034] A station (STA) is any device that includes a medium access control (MAC) and a physical layer interface for a wireless medium according to the IEEE 802.11 standard. In a broad sense, the term "station" encompasses not only non-AP stations but also APs. In this specification, the term "terminal" refers to either a non-AP or an AP, or both. A station for wireless communication includes a processor and a communication unit, and may further include a user interface and a display unit, depending on the embodiment. The processor generates frames to be transmitted over a wireless network, processes frames received over the wireless network, and performs various other processes for controlling the station. The communication unit is functionally connected to the processor and transmits and receives frames over the wireless network for the station. In this specification, the term "terminal" encompasses user equipment (UE).

[0035] An access point (AP) is an entity that provides a connection to a distribution system (DS) via a wireless medium for associated stations. In an infrastructure BSS, communication between non-AP stations is generally performed via the AP. However, if a direct link is established, direct communication is also possible between non-AP stations. Meanwhile, in the present invention, the term AP is used as a concept including a personal BSS coordination point (PCP), but in a broader sense, it also includes concepts such as a central controller, a base station (BS), a node B, a base transceiver system (BTS), or a site controller. In the present invention, an AP is also referred to as a base wireless communication terminal, but in a broader sense, the term base wireless communication terminal is used as a term including an AP, a base station, an eNodeB (eNB), and a transmission point (TP). In addition, the base wireless communication terminal includes various types of wireless communication terminals that allocate communication medium resources and perform scheduling for communication with multiple wireless communication terminals.

[0036] A plurality of infrastructure BSSs are connected to each other via a distribution system DS, and the plurality of BSSs connected via the distribution system are called an Extended Service Set (ESS).

[0037] 2 is a diagram showing an independent BSS, which is a wireless LAN system according to another embodiment of the present invention. In the embodiment of FIG. 2, the same or corresponding parts as those in the embodiment of FIG. 1 will not be described again.

[0038] BSS3 shown in Figure 2 is an independent BSS and does not include an AP, so none of the stations (STA6, STA7) are connected to an AP. An independent BSS is not allowed to connect to a distribution system and forms a self-contained network. In an independent BSS, each station (STA6, STA7) is directly connected to each other.

[0039] 3 is a block diagram showing the configuration of a station 100 according to an embodiment of the present invention. As shown, the station 100 according to the embodiment of the present invention includes a processor 110, a communication unit 120, a user interface unit 140, a display unit 150, and a memory 160.

[0040] First, the communication unit 120 transmits and receives wireless signals such as WLAN packets and may be incorporated into or external to the station 100. According to an embodiment, the communication unit 120 may include at least one communication module using different frequency bands. For example, the communication unit 120 may include communication modules using different frequency bands such as 2.4 GHz, 5 GHz, 6 GHz, and 60 GHz. According to an embodiment, the station 100 may include a communication module using a frequency band above 7.125 GHz and a communication module using a frequency band below 7.125 GHz. Each communication module may perform wireless communication with an AP or an external station based on the WLAN standard of the frequency band supported by the communication module. The communication unit 120 may operate only one communication module at a time or multiple communication modules simultaneously, depending on the performance and requirements of the station 100. When the station 100 includes multiple communication modules, each communication module may be provided independently, or multiple modules may be integrated into a single chip. In the embodiment of the present invention, the communication unit 120 may represent a radio frequency (RF) communication module that processes RF signals.

[0041] Next, the user interface 140 includes various types of input / output means provided in the station 100. That is, the user interface unit 140 receives user input using various input means, and the processor 110 controls the station 100 based on the received user input. Also, the user interface unit 140 performs output based on instructions from the processor 110 using various output means.

[0042] The display unit 150 then outputs an image on a display screen. The display unit 150 outputs various display objects, such as a user interface, based on the contents or control commands of the processor 110. The memory 160 also stores control programs and various data used by the station 100. The control programs include a connection program required for the station 100 to connect to an AP or an external station.

[0043] The processor 110 of the present invention executes various commands or programs to process data within the station 100. The processor 110 also controls each unit of the station 100 and controls the transmission and reception of data between the units. According to an embodiment of the present invention, the processor 110 executes a program for connection with an AP stored in the memory 160 and receives a communication setup message transmitted by the AP. The processor 110 also reads information about the station 100's preferences contained in the communication setup message and requests connection to the AP based on the information about the station 100's preferences. The processor 110 of the present invention may refer to a main control unit of the station 100, or, depending on the embodiment, may refer to a control unit for individually controlling some components of the station 100, such as the communication unit 120. That is, the processor 110 may be a modem that modulates and demodulates wireless signals transmitted and received by the communication unit 120, or a modulator and / or demodulator. The processor 110 controls various operations for transmitting and receiving wireless signals in the station 100 according to an embodiment of the present invention. A detailed embodiment of this will be described later.

[0044] The station 100 shown in FIG. 3 is a block diagram according to an embodiment of the present invention, and the separate blocks indicate the logically separated elements of the device. Therefore, the above-described device elements may be implemented on a single chip or multiple chips depending on the device design. For example, the processor 110 and the communication unit 120 may be integrated into a single chip or may be implemented on separate chips. Furthermore, in embodiments of the present invention, some components of the station 100, such as the user interface unit 140 and the display unit 150, may be selectively included in the station 100.

[0045] 4 is a block diagram showing the configuration of an AP 200 according to an embodiment of the present invention. As shown, the AP 200 according to the embodiment of the present invention includes a processor 210, a communication unit 220, and a memory 260. In FIG. 4, duplicated descriptions of parts of the configuration of the AP 200 that are the same as or correspond to the configuration of the station 100 in FIG. 3 will be omitted.

[0046] Referring to FIG. 4, the AP 200 according to the present invention includes a communication unit 220 for operating a BSS in at least one frequency band. As described above in the embodiment of FIG. 3, the communication unit 220 of the AP 200 may also include multiple communication modules using different frequency bands. That is, the AP 200 according to the embodiment of the present invention may include two or more communication modules using different frequency bands, for example, 2.4 GHz, 5 GHz, 6 GHz, and 60 GHz. Preferably, the AP 200 may include a communication module using a frequency band above 7.125 GHz and a communication module using a frequency band below 7.125 GHz. Each communication module may perform wireless communication with a station based on the WLAN standard of the frequency band supported by the communication module. The communication unit 220 may operate only one communication module at a time or multiple communication modules simultaneously, depending on the performance and requirements of the AP 200. In the embodiment of the present invention, the communication unit 220 may represent an RF (Radio Frequency) communication module that processes RF signals.

[0047] The memory 260 stores control programs used by the AP 200 and various data associated therewith. These control programs include a connection program that manages station connections. The processor 210 also controls each unit of the AP 200 and controls data transmission and reception between the units. According to an embodiment of the present invention, the processor 210 executes a program for connecting with a station stored in the memory 260 and transmits a communication setup message to one or more stations. The communication setup message includes information regarding connection preferences for each station. The processor 210 also performs connection setup in response to a station connection request. According to an embodiment, the processor 210 is a modem or a modulation / demodulation unit that modulates and demodulates wireless signals transmitted and received from the communication unit 220. The processor 210 controls various operations for transmitting and receiving wireless signals by the AP 200 according to an embodiment of the present invention. A detailed embodiment of this will be described later.

[0048] FIG. 5 is a diagram illustrating a process in which a STA establishes a link with an AP.

[0049] 5, a link between the STA 100 and the AP 200 is established through three steps: scanning, authentication, and association. First, the scanning step is a step in which the STA 100 acquires connection information for the BSS operated by the AP 200. There are two scanning methods: a passive scanning method in which the STA 100 acquires information using only a beacon message S101 periodically transmitted by the AP 200, and an active scanning method in which the STA 100 acquires connection information by transmitting a probe request to the AP (S103) and receiving a probe response from the AP (S105).

[0050] The STA 100 that has successfully received wireless connection information in the scanning step transmits an authentication request (S107a), receives an authentication response from the AP 200 (S107b), and performs the authentication step. After the authentication step is performed, the STA 100 transmits an association request (S109a), receives an association response from the AP 200, and performs the association step (S109b). In this specification, association basically means wireless association, but the present invention is not limited to this, and association in a broad sense includes both wireless and wired association.

[0051] Meanwhile, an 802.1X-based authentication step S111 and an IP address acquisition step S113 via DHCP are additionally performed. In Fig. 5, server 300 is a server that processes 802.1X-based authentication with STA 100, and may be physically connected to AP 200 or may exist as a separate server.

[0052] FIG. 6 is a diagram showing a CSMA (Carrier Sense Multiple Access) / CA (Collision Avoidance) method used in wireless LAN communication.

[0053] A terminal performing WLAN communication performs carrier sensing to check whether a channel is occupied before transmitting data. If a wireless signal above a certain strength is detected, the channel is determined to be occupied, and the terminal delays access to the channel. This process is called Clear Channel Assessment (CCA), and the level that determines whether or not a signal is detected is called the CCA threshold. If a wireless signal above the CCA threshold is received by the terminal and the terminal is the receiver, the terminal processes the received wireless signal. On the other hand, if no wireless signal is detected from the channel or a wireless signal with a strength below the CCA threshold is detected, the channel is determined to be idle.

[0054] If the channel is determined to be idle, each terminal with data to transmit performs a backoff procedure after an IFS (Inter Frame Space), such as an AIFS (Arbitration IFS) or a PIFS (PCF IFS), depending on the status of each terminal. In some embodiments, the AIFS is used as a configuration replacing the conventional DIFS (DCF IFS). Each terminal waits while decreasing a slot time by a random number determined for the corresponding terminal during the idle interval of the channel, and a terminal that has exhausted all slot times attempts to access the corresponding channel. The period during which each terminal performs the backoff procedure is called a contention window period.

[0055] If a specific terminal successfully accesses the channel, it transmits data over the channel. However, if the terminal attempting access collides with another terminal, the colliding terminals are assigned new random numbers and perform a backoff procedure again. According to one embodiment, the new random numbers assigned to each terminal are determined within a range (2*CW) twice the range of the random numbers previously assigned to the terminal (contention window, CW). Meanwhile, each terminal attempts access by performing a backoff procedure again in the next contention window period. At this time, each terminal performs the backoff procedure from the slot time remaining in the previous contention window period. In this way, terminals communicating over a wireless LAN can avoid collisions with each other on a specific channel.

[0056] Hereinafter, in the present invention, a terminal may be referred to as a non-AP STA, an AP STA, an AP, an STA, a receiving device, or a transmitting device, and the present invention is not limited thereto. Also, in the present invention, an AP STA may be referred to as an AP.

[0057] <Examples of various PPDU formats> Figure 7 shows examples of various standard generation PPDU (PLCP Protocol Data Unit) formats. More specifically, Figure 7(a) shows an example of a legacy PPDU format based on 802.11a / g, Figure 7(b) shows an example of an HE PPDU format based on 802.11ax, and Figure 7(c) shows an example of a non-legacy PPDU (i.e., EHT PPDU) format based on 802.11be. Also, Figure 7(d) shows detailed field configurations of L-SIG and RL-SIG commonly used in the PPDU formats.

[0058] 7(a), the preamble of the legacy PPDU includes a Legacy Short Training field (L-STF), a Legacy Long Training field (L-LTF), and a Legacy Signal field (L-SIG). In an embodiment of the present invention, the L-STF, L-LTF, and L-SIG may be referred to as a legacy preamble.

[0059] Referring to FIG. 7(b), the preamble of the HE PPDU further includes a Repeated Legacy Short Training field (RL-SIG), a High Efficiency Signal A field (HE-SIG-A), a High Efficiency Signal B field (HE-SIG-B), a High Efficiency Short Training field (HE-STF), and a High Efficiency Long Training field (HE-LTF) in addition to the legacy preamble. In an embodiment of the present invention, the RL-SIG, HE-SIG-A, HE-SIG-B, HE-STF, and HE-LTF can be referred to as an HE preamble. The specific configuration of the HE preamble may vary depending on the HE PPDU format. For example, HE-SIG-B may be used only in the HE MU PPDU format.

[0060] Referring to FIG. 7(c), the preamble of the EHT PPDU further includes a Repeated Legacy Short Training field (RL-SIG), a Universal Signal field (U-SIG), an Extremely High Throughput Signal A field (EHT-SIG-A), an Extremely High Throughput Signal B field (EHT-SIG-A), an Extremely High Throughput Short Training field (EHT-STF), and an Extremely High Throughput Long Training field (EHT-LTF) in addition to the legacy preamble. In an embodiment of the present invention, the RL-SIG, EHT-SIG-A, EHT-SIG-B, EHT-STF, and EHT-LTF may be referred to as an EHT preamble. The specific configuration of the non-legacy preamble may vary depending on the EHT PPDU format. For example, EHT-SIG-A and EHT-SIG-B may be used only in some EHT PPDU formats.

[0061] The L-SIG field included in the PPDU preamble is configured with a total of 64 subcarriers using 64 FFT OFDM. Of these, 48 subcarriers, excluding guard subcarriers, DC subcarriers, and pilot subcarriers, are used for L-SIG data transmission. BPSK and Rate=1 / 2 MCS (Modulation and Coding Scheme) are applied to the L-SIG, so it can contain a total of 24 bits of information. Figure 7(d) shows the 24-bit information structure of the L-SIG.

[0062] Referring to FIG. 7(d), the L-SIG includes an L_RATE field and an L_LENGTH field. The L_RATE field is composed of 4 bits and indicates the MCS used for data transmission. Specifically, the L_RATE field indicates one of the transmission rates of 6, 9, 12, 18, 24, 36, 48, or 54 Mbps, which is a combination of a modulation scheme such as BPSK, QPSK, 16-QAM, or 64-QAM and a code rate such as 1 / 2, 2 / 3, or 3 / 4. The combined information in the L_RATE and L_LENGTH fields indicates the total length of the PPDU. In a non-legacy PPDU format, the L_RATE field is set to the minimum rate of 6 Mbps.

[0063] The unit of the L_LENGTH field is bytes, and a total of 12 bits are allocated, allowing a maximum of 4095 to be signaled. In combination with the L_RATE field, it can indicate the length of the corresponding PPDU. In this case, legacy and non-legacy terminals can interpret the L_LENGTH field in different ways.

[0064] First, a legacy or non-legacy terminal interprets the length of the corresponding PPDU using the L_LENGTH field as follows. When the value of the L_RATE field is set to indicate 6 Mbps, 3 bytes (i.e., 24 bits) may be transmitted during 4 us, which is one symbol duration of the 64FFT. Therefore, by adding the 3 bytes corresponding to the SVC field and Tail field to the L_LENGTH field value and dividing this by 3 bytes, which is the transmission amount of one symbol, the number of 64FFT reference symbols after the L-SIG is obtained. The obtained number of symbols is multiplied by 4 us, which is one symbol duration, and then 20 us, which is required to transmit the L-STF, L-LTF, and L-SIG, to obtain the length of the corresponding PPDU, i.e., the reception time (RXTIME). This can be expressed mathematically as shown in Equation 1 below.

[0065]

number

[0066] At this time,

number

[0067]

number

[0068] Here, TXTIME is the total transmission time constituting the PPDU, and is expressed as the following equation 3. In this case, TX represents the transmission time of X.

[0069]

number

[0070] Referring to the above formula, the length of the PPDU is calculated based on the rounded up value of L_LENGTH / 3. Therefore, for any value of k, three different values ​​of L_LENGTH={3k+1, 3k+2, 3(k+1)} indicate the same PPDU length.

[0071] Referring to Figure 7(e), the U-SIG (Universal SIG) field remains in the EHT PPDU and subsequent generation WLAN PPDUs, and serves to distinguish which generation of PPDU it is, including 11be. The U-SIG is two 64FFT-based OFDM symbols and can transmit a total of 52 bits of information. Of these, 43 bits excluding 9 bits of CRC / tail are roughly divided into a VI (Version Independent) field and a VD (Version Dependent) field.

[0072] The VI bit will maintain its current bit configuration, so even if a subsequent generation PPDU is defined, current 11be UEs can obtain information about the PPDU from the VI field of the PPDU. To this end, the VI field consists of the PHY version, UL / DL, BSS color, TXOP, and Reserved fields. The PHY version field is 3 bits long and serves to sequentially distinguish between 11be and subsequent generations of WLAN standards. 11be has a value of 000b. The UL / DL field identifies whether the PPDU is an uplink or downlink PPDU. The BSS color represents a BSS identifier defined in 11ax and has a value of 6 or more bits. The TXOP represents the transmit opportunity duration (Transmit Opportunity Duration) transmitted in the MAC header. By adding it to the PHY header, the length of the TXOP containing the PPDU can be inferred without decoding the MPDU, and has a value of 7 or more bits.

[0073] The VD field, which is signaling information useful only for 11be version PPDUs, may consist of fields commonly used in any PPDU format, such as the PPDU format and BW, as well as fields defined differently for each PPDU format. The PPDU format is a separator that distinguishes between EHT SU (Single User), EHT MU (Multiple User), EHT TB (Trigger-based), and EHT ER (Extended Range) PPDUs. The BW field broadly signals five basic PPDU BW options: 20, 40, 80, 160 (80 + 80), and 320 (160 + 160) MHz (BWs that can be expressed in the form of a power of 20 * 2 can be called basic BWs), as well as various remaining PPDU BWs formed by preamble puncturing. After signaling at 320 MHz, a portion of 80 MHz may be punctured. In addition, the punctured and modified channel shape may be signaled directly in the BW field, or may be signaled using both the BW field and a field that appears after the BW field (for example, a field in the EHT-SIG field). If the BW field is 3 bits, a total of 8 BW signalings are possible, so a maximum of 3 puncturing modes can be signaled. If the BW field is 4 bits, a total of 16 BW signalings are possible, so a maximum of 11 puncturing modes can be signaled.

[0074] The fields located after the BW field vary depending on the type and format of the PPDU. MU PPDUs and SU PPDUs may be signaled using the same PPDU format, and a field for distinguishing between MU PPDUs and SU PPDUs may be located before the EHT-SIG field, requiring additional signaling. Both SU PPDUs and MU PPDUs include an EHT-SIG field, but some fields not required for the SU PPDU may be compressed. In this case, the information of the compressed fields may be omitted or may have a reduced size compared to the size of the original fields included in the MU PPDU. For example, the SU PPDU may have a different configuration, such as the common fields of the EHT-SIG being omitted or replaced, or the user-specific fields being replaced or reduced to one.

[0075] Alternatively, the SU PPDU may further include a compression field indicating whether or not it is compressed, and some fields (such as the RA field) may be omitted depending on the value of the compression field.

[0076] When a portion of the EHT-SIG field of the SU PPDU is compressed, the information included in the compressed field may be signaled together in an uncompressed field (e.g., a common field). In the case of an MU PPDU, since it is a PPDU format for simultaneous reception by multiple users, the EHT-SIG field must be transmitted after the U-SIG field, and the amount of information signaled may be variable. That is, since multiple MU PPDUs are transmitted to multiple STAs, each STA must recognize the location of the RU to which the MU PPDU is transmitted, the STA to which each RU is assigned, and whether the transmitted MU PPDU was sent to it. Therefore, the AP must transmit the above information in the EHT-SIG field. To this end, the U-SIG field signals information for efficiently transmitting the EHT-SIG field, which may be the number of symbols in the EHT-SIG field and / or the MCS, which is the modulation method. The EHT-SIG field may include information on the size and location of the RU assigned to each user.

[0077] In the case of an SU PPDU, a STA may be assigned multiple RUs, and the multiple RUs may be contiguous or discontinuous. If the RUs assigned to the STA are not contiguous, the STA can efficiently receive the SU PPDU only by recognizing punctured RUs in between. Therefore, the AP can transmit the SU PPDU including information on punctured RUs among the RUs assigned to the STA (e.g., puncturing pattern of the RUs). That is, in the case of an SU PPDU, a puncturing mode field including information indicating whether a puncturing mode is applied and the puncturing pattern in a bitmap format, etc., may be included in the EHT-SIG field, and the puncturing mode field can signal the type of discontinuous channels appearing within the bandwidth.

[0078] The type of signaled discontinuous channel is limited, and indicates the BW and discontinuous channel information of the SU PPDU in combination with the value of the BW field. For example, since the SU PPDU is a PPDU transmitted only to a single UE, the STA can recognize its allocated bandwidth from the BW field included in the PPDU and can recognize punctured resources within the allocated bandwidth from the puncturing mode field of the U-SIG field or EHT-SIG field included in the PPDU. In this case, the UE can receive the PPDU in the remaining resource units excluding specific channels of the punctured resource units. In this case, multiple RUs allocated to the STA may be configured with different frequency bands or tones.

[0079] The reason why only limited discontinuous channel types are signaled is to reduce the signaling overhead of the SU PPDU. Since puncturing can be performed for each 20 MHz subchannel, if puncturing is performed on a BW having multiple 20 MHz subchannels, such as 80, 160, and 320 MHz, in the case of 320 MHz, the discontinuous channel type (when only the end 20 MHz is punctured and considered discontinuous) must be signaled by expressing whether or not each of the remaining 15 20 MHz subchannels excluding the primary channel is in use. Using 15 bits to signal the discontinuous channel type for single-user transmission can result in excessive signaling overhead when considering the low transmission rate of the signaling part.

[0080] This invention proposes a method for signaling the discontinuous channel type of the SU PPDU, shows the discontinuous channel type determined by the proposed method, and proposes a method for signaling the primary 160 MHz and secondary 160 MHz puncturing types in the 320 MHz BW configuration of the SU PPDU.

[0081] In addition, one embodiment of the present invention proposes a method of varying the PPDU configuration indicated by the preamble puncturing BW value according to the PPDU format signaled in the PPDU format field. Assuming the length of the BW field is 4 bits, in the case of an EHT SU PPDU or TB PPDU, an EHT-SIG-A symbol of one symbol may be further signaled after the U-SIG, or no EHT-SIG-A may be signaled at all. Taking this into consideration, up to 11 puncturing modes must be signaled using only the BW field of the U-SIG. However, in the case of an EHT MU PPDU, an EHT-SIG-B symbol is further signaled after the U-SIG, so up to 11 puncturing modes may be signaled in a different manner than in the SU PPDU. In the case of an EHT ER PPDU, the BW field can be set to 1 bit to signal whether the PPDU uses a 20 MHz or 10 MHz bandwidth.

[0082] Figure 7(f) shows the format-specific field configuration of the VD field when the PPDU format field of the U-SIG indicates an EHT MU PPDU. For an MU PPDU, SIG-B, a signaling field for simultaneous reception by multiple users, is required. SIG-B may be transmitted after the U-SIG without a separate SIG-A. For this purpose, the U-SIG must signal information for decoding SIG-B. These fields include the SIG-B MCS, SIG-B DCM, number of SIG-B symbols, SIG-B compression, and number of EHT-LTF symbols.

[0083] FIG. 8 illustrates various Extremely High Throughput (EHT) Physical Protocol Data Unit (PPDU) formats and exemplary methods for indicating the same according to an embodiment of the present invention.

[0084] 8, a PPDU may be configured with a preamble and a data portion, and the format of one type, EHT PPDU, may be distinguished by a U-SIG field included in the preamble. Specifically, whether the format of the PPDU is EHT PPDU may be indicated based on a PPDU format field included in the U-SIG field.

[0085] 8(a) shows an example of an EHT SU PPDU format for a single STA. The EHT SU PPDU is a PPDU used for single user (SU) transmission between an AP and a single STA, and an EHT-SIG-A field for additional signaling may be located after the U-SIG field.

[0086] 8(b) shows an example of an EHT trigger-based PPDU format, which is an EHT PPDU transmitted based on a trigger frame. The EHT trigger-based PPDU is an EHT PPDU transmitted based on a trigger frame and is an uplink PPDU used for responding to the trigger frame. Unlike the EHT SU PPDU, the EHT PPDU does not have an EHT-SIG-A field after the U-SIG field.

[0087] 8(c) shows an example of an EHT MU PPDU format, which is an EHT PPDU for multiple users. The EHT MU PPDU is a PPDU used to transmit a PPDU to one or more STAs. In the EHT MU PPDU format, an HE-SIG-B field may be located after the U-SIG field.

[0088] 8(d) shows an example of an EHT ER SU PPDU format used for single-user transmission with STAs in an extended range. The EHT ER SU PPDU may be used for single-user transmission with STAs in a wider range than the EHT SU PPDU described in FIG. 8(a), and the U-SIG field may be repeated on the time axis.

[0089] The EHT MU PPDU described in (c) of Figure 8 can be used by the AP for downlink transmission to multiple STAs. In this case, the EHT MU PPDU can include scheduling information so that multiple STAs can simultaneously receive the PPDU transmitted from the AP. The EHT MU PPDU can convey AID information of the receiver and / or sender of the transmitted PPDU to the STA through the user specific field of the EHT-SIG-B. Therefore, multiple terminals receiving the EHT MU PPDU can perform spatial reuse based on the AID information of the user specific field included in the preamble of the received PPDU.

[0090] Specifically, the resource unit allocation (RA) field of the HE-SIG-B field included in the HE MU PPDU may include information regarding the configuration of resource units (e.g., the division type of resource units) in a specific bandwidth (e.g., 20 MHz) on the frequency axis. That is, the RA field may indicate the configuration of resource units divided by the bandwidth for transmitting the HE MU PPDU so that the STA can receive the PPDU. Information about the STA allocated (or designated) to each divided resource unit may be included in a user specific field of the EHT-SIG-B and transmitted to the STA. That is, the user specific field may include one or more user fields corresponding to each divided resource unit.

[0091] For example, among the multiple divided resource units, the user field corresponding to at least one resource unit used for data transmission may include the AID of the receiver or sender, and the user field corresponding to the remaining resource units not used for data transmission may include a previously set null STA ID.

[0092] Two or more PPDUs shown in FIG. 8 can be indicated by a value indicating the same PPDU format. That is, two or more PPDUs can be indicated as the same PPDU format by the same value. For example, an EHT SU PPDU and an EHT MU PPDU can be indicated by the same value using the U-SIG PPDU format subfield. In this case, the EHT SU PPDU and the EHT MU PPDU can be distinguished depending on the number of STAs receiving the PPDU. For example, a PPDU received by only one STA may be identified as an EHT SU PPDU, and when the number of STAs is set so that two or more STAs can receive the PPDU, it may be identified as an EHT MU PPDU. In other words, two or more PPDU formats shown in FIG. 8 can be indicated using the same subfield value.

[0093] In addition, some of the fields or some information of the fields shown in Figure 8 may be omitted, and such a case where some of the fields or some information of the fields is omitted can be defined as a compression mode or a compressed mode.

[0094] FIG. 9 is a diagram illustrating a multi-link device according to an embodiment of the present invention.

[0095] Referring to FIG. 9, the concept of a device to which one or more STAs are affiliated may be defined. As another example, according to an embodiment of the present invention, a device to which more than one STA is affiliated (i.e., two or more) may be defined. In this case, the device may be a logical concept. Therefore, such a device to which one or more STAs are affiliated may be referred to as a multi-link device (MLD), a multi-band device, or a multi-link logical entity (MLLE).

[0096] Alternatively, the above conceptual device can be called a multi-link entity (MLE). Also, the MLD may have one MAC medium access control service access point (SAP) to the logical link control (LLC), and the MLD may have one MAC data service.

[0097] A STA included in an MLD can operate on one or more links or channels. That is, a STA included in an MLD can operate on multiple different channels. For example, a STA included in an MLD can operate using channels in different frequency bands, such as 2.4 GHz, 5 GHz, and 6 GHz. This allows MLD to obtain gains in channel access and improve overall network performance. While existing WLANs operate on a single link, MLD operation can use multiple links to obtain more channel access opportunities or allow STAs to operate efficiently on multiple links taking into account channel conditions.

[0098] Also, if the STA affiliated to the MLD is an AP, the MLD to which the AP is affiliated may be an AP MLD, whereas if the STA affiliated to the MLD is a non-AP STA, the MLD to which the non-AP is affiliated may be a non-AP MLD.

[0099] An AP MLD (Multi-link Device) is a device that includes one or more wireless access points (APs) and is connected to a higher layer via one interface. That is, the AP MLD is connected to the Logical Link Control (LLC) layer via one interface. Multiple APs included in an AP MLD share some functions in the MAC layer. Each AP in an AP MLD operates on a different link. An STA MLD is a device that includes one or more non-AP STAs and is connected to a higher layer via one interface.

[0100] In other words, the STA MLD is connected to the LLC layer through one interface. Multiple STAs included in the STA MLD share some functions in the MAC layer. The STA MLD is also called non-AP MLD. The AP MLD and STA MLD perform multi-link operations, communicating using multiple individual links. That is, if the AP MLD includes multiple APs, each AP configures a separate link and transmits and receives frames using multiple links with each STA included in the STA MLD. Each link operates in the 2.4 GHz, 5 GHz, or 6 GHz band, and each link performs bandwidth expansion. For example, if the AP MLD configures one link in the 2.4 GHz band and two links in the 5 GHz band, the 2.4 GHz band transmits frames at a bandwidth of 40 MHz using the bandwidth expansion method, and each link using the 5 GHz band transmits frames at a maximum bandwidth of 320 MHz by utilizing non-contiguous bandwidth.

[0101] Meanwhile, due to interference issues within devices, the AP MLD or STA MLD does not allow a terminal within the MLD to perform a receiving operation while another terminal is transmitting. This operation, in which one AP or terminal within the MLD is transmitting while another AP or terminal within the MLD is receiving, is called STR (Simultaneous Transmit and Receive). The AP MLD is capable of STR operation for all links. Alternatively, STR operation is not possible for some links of the AP MLD. The AP MLD is accessed by terminal MLDs capable of STR operation, and MLDs incapable of STR operation for some or all links. Furthermore, APs included in the AP MLD are additionally accessed by terminals not belonging to the MLD (e.g., IEEE 802.11a / b / g / n / ac / ax terminals).

[0102] The AP MLD and STA MLD negotiate for the use of multiple links during the scanning and access process described in Figure 5. For example, during the scanning process described in Figure 5, the AP included in the AP MLD transmits a beacon frame including an indicator indicating that multiple link operation is available, the number of available links, and information on the multiple available links. Also, a terminal belonging to the STA MLD transmits a probe request frame including an indicator indicating that multiple link operation is available, and an AP belonging to the AP MLD transmits a probe response frame including an indicator indicating that multiple link operation is available. In this case, the AP additionally transmits the number of available links, link information, etc., during the multiple link operation.

[0103] During the scanning process, the STA MLD, which has confirmed whether the AP MLD is capable of multi-link operation and the link information to be used, performs an access process with the AP MLD. At this time, the AP MLD and the STA MLD start a negotiation process for performing multi-link operation. At this time, the negotiation process for the multi-link operation is performed during the access process between an AP belonging to the AP MLD and a terminal belonging to the STA MLD. That is, a terminal (e.g., STA1) belonging to the STA MLD sends an access request frame to an AP (e.g., AP1) belonging to the AP MLD, transmitting an indicator indicating that the terminal is capable of multi-link operation and a request indicator requesting multi-link operation. Upon receiving the access request frame from the terminal, the AP checks the indicator requesting multi-link operation. If the AP is capable of multi-link operation, the AP transmits an access response frame to the terminal, which allows the multi-link operation and includes link information to be used for the multi-link operation and parameters to be used for each link. The parameters for the multi-link operation include one or more of the bandwidth of each link to be used, the bandwidth expansion direction, the Target Beacon Transmission Time (TBTT), and whether STR operation is possible. The AP MLD and STA MLD, which have confirmed the use of multiple link operation by exchanging the access request frame and response frame, perform frame transmission operations using multiple links using multiple APs included in the AP MLD and multiple terminals included in the STA MLD after the corresponding access process.

[0104] 9, an MLD including multiple STAs may exist, and the multiple STAs included in the MLD may operate on multiple links. In FIG. 9, an MLD including APs AP1, AP2, and AP3 may be referred to as an AP MLD, and an MLD including non-AP STAs non-AP STA1, non-AP STA2, and non-AP STA3 may be referred to as a non-AP MLD. STAs included in the MLD may operate on Link 1, Link 2, Link 3, or some of Links 1 to 3.

[0105] According to an embodiment of the present invention, the multi-link operation may include a multi-link setup operation. The multi-link setup operation may be an operation corresponding to the association performed in the single-link operation. To exchange frames over the multiple links, the multi-link setup may be preceded by the multi-link setup. The multi-link setup operation may be performed using a multi-link setup element. Here, the multi-link setup element may include capability information related to the multiple links. The capability information may include information related to whether a STA included in the MLD can receive a frame over one link while another STA included in the MLD can transmit a frame over another link. That is, the capability information may include information related to whether a STA (non-AP STA and / or AP (or AP STA)) can simultaneously transmit / receive frames in different transmission directions over the links included in the MLD. The capability information may also include information related to available links or operating channels. The multi-link setup may be set up through negotiation between peer STAs, and the multi-link operation may be set up over one link.

[0106] According to one embodiment of the present invention, a mapping relationship may exist between a TID and a link of an MLD. For example, when a TID and a link are mapped, the TID may be transmitted on the mapped link. The mapping between a TID and a link may be directional-based. For example, a mapping may be performed for each of the two directions between MLD1 and MLD2. Furthermore, a default setting may exist for the mapping between a TID and a link. For example, the mapping between a TID and a link may basically be such that all TIDs are mapped to a certain link.

[0107] FIG. 10 is a diagram illustrating an example of a TID-to-link mapping method according to an embodiment of the present invention.

[0108] Referring to Figure 10, there is a mapping relationship between TIDs and links as described in Figure 9. In addition, in the present invention, the mapping relationship between TIDs and links is referred to as TID-to-link mapping, TID to link mapping, TID mapping, link mapping, etc. TID is a traffic identifier. In addition, TID is an identifier that classifies traffic, data, etc. to support quality of service (QoS).

[0109] TID is an ID used or assigned in a layer higher than the MAC layer. TID indicates traffic categories (TC) or traffic streams (TS). TID has 16 values, for example, 0 to 15. The TID value used varies depending on the access policy, channel access, or medium access method. For example, when EDCA (HCF (hybrid coordination function) contention-based channel access, enhanced distributed channel access) is used, the possible TID values ​​are 0 to 7. When EDCA is used, the TID value indicates UP (user priority), where UP relates to TC or TS. UP is a value assigned in a layer higher than MAC. When HCCA (HCF controlled channel access) or SPCA is used, the possible TID values ​​are 8 to 15. When HCCA or SPCA is used, TID indicates TSID. When HEMM or SEMM is used, the possible TID values ​​are 8 to 15. When HEMM or SEMM is used, TID indicates TSID.

[0110] There is also a mapping relationship between UP and access category (AC). AC is a label that indicates a label or a set of EDCA parameters for providing QoS in EDCA. The EDCA parameter or set of EDCA parameters is used for channel association. AC is used by QoS STA.

[0111] The AC value is set to one of AC_BK, AC_BE, AC_VI, and AC_VO. AC_BK, AC_BE, AC_VI, and AC_VO indicate background, best effort, video, and voice, respectively. AC_BK, AC_BE, AC_VI, and AC_VO can be further subdivided. For example, AC_VI is subdivided into AC_VI primary and AC_VI alternate. AC_VO is further subdivided into AC_VO primary and AC_VO alternate. UP values ​​or TID values ​​are mapped to AC values. For example, UP values ​​or TID values ​​of 1, 2, 0, 3, 4, 5, 6, and 7 are mapped to AC_BK, AC_BK, AC_BE, AC_BE, AC_VI, AC_VI, AC_VO, and AC_VO, respectively. Alternatively, UP or TID values ​​1, 2, 0, 3, 4, 5, 6, and 7 are mapped to AC_BK, AC_BK, AC_BE, AC_BE, AC_VI alternate, AC_VI primary, AC_VO primary, and AC_VO alternate, respectively. UP or TID values ​​1, 2, 0, 3, 4, 5, 6, and 7 have increasing priority in that order. That is, 1 has a lower priority, and 7 has a higher priority. Therefore, the order of priority is AC_BK, AC_BE, AC_VI, and AC_VO. AC_BK, AC_BE, AC_VI, and AC_VO correspond to AC index (ACI) 0, 1, 2, and 3, respectively.

[0112] Therefore, there is a relationship between TID and AC. Therefore, the TID-to-link mapping of the present invention is also a mapping relationship between AC and link. In addition, in the present invention, when a TID is mapped, it means that an AC is also mapped, and vice versa.

[0113] According to one embodiment of the present invention, a TID is mapped to each link of a multi-link. For example, there is a mapping that indicates which link among multiple links a specific TID or a specific AC is allowed to transmit or receive on. Furthermore, such mapping is defined separately for each direction of the link. Furthermore, as described above, there is a default setting for the mapping between TIDs and links. For example, the mapping between TIDs and links is such that all TIDs are basically mapped to a certain link. Furthermore, according to one embodiment, a certain TID or a certain AC is mapped to at least one link at a specific time. Furthermore, management frames or control frames are transmitted from all links.

[0114] In the present invention, a data frame corresponding to a TID or AC mapped to a certain direction of a link is transmitted, and a data frame corresponding to a TID or AC not mapped to a certain direction of a link is not transmitted.

[0115] According to one embodiment, the TID-to-link mapping also applies to the acknowledgment. For example, a block ack agreement is based on the TID-to-link mapping. Alternatively, the TID-to-link mapping is based on the block ack agreement. For example, a block ack agreement exists for the TID-to-link mapped TID.

[0116] TID-to-link mapping provides QoS service. For example, by mapping a high-priority AC and TID to a link with good channel conditions or few STAs, data for the corresponding AC and TID can be transmitted faster. Alternatively, TID-to-link mapping can help STAs on a specific link save power (or enter a doze state).

[0117] 10, there is an AP MLD including AP1 and AP2. There is also a Non-AP MLD including STA1 and STA2. The AP MLD also includes multiple links, link1 and link2. AP1 and STA1 are associated via link1, and AP2 and STA2 are associated via link2.

[0118] Therefore, Link1 includes a link from AP1 to STA1 and / or a link from STA1 to AP1, and Link2 includes a link from AP2 to STA2 and / or a link from STA2 to AP2, where each link is mapped with a TID and / or AC.

[0119] For example, all TIDs and ACs are mapped to Link1, the link transmitting from AP1 to STA1, and Link1, the link transmitting from STA1 to AP1. Also, only AC_VO or TIDs corresponding to AC_VO are mapped to Link2, the link transmitting from STA2 to AP2. Also, only data of mapped TIDs and / or ACs is transmitted from the corresponding link. Also, data of TIDs or ACs not mapped to a link is not transmitted from the corresponding link.

[0120] FIG. 11 is a diagram illustrating an example of a multi-link NAV setting operation according to an embodiment of the present invention.

[0121] The simultaneous transmit and receive (STR) operation of MLD is limited, which is related to the frequency spacing between the multiple links operating in the multi-link.

[0122] Therefore, according to an embodiment of the present invention, simultaneous transmission or reception is restricted when the spacing between links is m MHz, but simultaneous transmission or reception is not restricted when the spacing between links is n MHz for n greater than m. This embodiment is intended to solve the problem of restrictions on simultaneous transmission or reception, and redundant explanations will be omitted. The embodiment of the present invention can be applied to MLDs that do not support STR.

[0123] According to one embodiment of the present invention, duration information is shared between links operating in a multi-link configuration. In one embodiment, the duration information is TXOP duration information transmitted from a signaling field of a preamble. The signaling field is the U-SIG field described above. Alternatively, the signaling field is the HE-SIG-A field described above. In another embodiment, the duration information is duration information indicated by a Duration / ID field included in a MAC header. In still another embodiment, the duration information is duration information indicated by a Length field (L Length field) included in an L-SIG field. According to one embodiment, the duration information indicated by the U-SIG field, HE-SIG-A, or Duration / ID field is a value indicating the TXOP duration. According to one embodiment, the duration information indicated by the L-SIG field is a value indicating the length of a PPDU (physical layer protocol data unit) including the L-SIG field or the end of a PPDU including the L-SIG field.

[0124] According to an embodiment of the present invention, transmission or channel access is restricted for a period based on period information shared between links. The method of restricting transmission or channel access includes setting a NAV or resetting the NAV to resume transmission or channel access. In this case, the NAV is an intra-BSS NAV. The intra-BSS NAV is a NAV set by an intra-BSS frame (or PPDU). That is, a STA belonging to an MLD sets its NAV based on a frame (or PPDU) addressed to another STA belonging to the MLD.

[0125] According to one embodiment of the present invention, an inter-link NAV exists. The inter-link NAV is a NAV used by STAs of multiple links belonging to an MLD when operating with multiple links. For example, transmission on link 2 may not be required based on the inter-link NAV set based on period information received on link 1. In addition, the inter-link NAV exists or is used for MLDs that are not capable of STR. For example, if an inter-link NAV is set, the MLD that set the corresponding inter-link NAV does not transmit or access channels on multiple links (or all links used by the MLD).

[0126] In addition to intra-BSS NAV, there is also basic NAV, which is a type of NAV that is set by an inter-BSS frame (or PPDU), and is also set by a frame (or PPDU) that is not determined to be intra-BSS or inter-BSS.

[0127] Using inter-link NAV separately has advantages over not using inter-link NAV in situations where NAV settings are updated. For example, there are situations where it is acceptable to reset a NAV set by another link. For example, if an inter-link NAV is set based on a certain frame (or PPDU), but it is determined that the frame (or PPDU) is not destined for the same MLD, it is acceptable to reset the set inter-link NAV. If an MLD exists that operates on link 1 and link 2, the NAV for link 1 may have been set based on a frame received on link 1. Then, the NAV for link 1 is updated based on the frame from link 2. If the NAV for link 1 is reset when it is no longer necessary to maintain the NAV for link 2, the NAV information set based on the frame received on link 1 may be lost. If inter-link NAV is used together with the NAV for each link, this problem can be solved because the NAV for each link can be indicated even if the inter-link NAV is reset.

[0128] Although the embodiment of the present invention exemplifies setting the NAV, the embodiment of the present invention is not limited to this and may be applied to instructing the physical layer to suspend channel access or instructing the channel state to be busy. Furthermore, the embodiment is not limited to resetting the NAV and may be applied to instructing the physical layer to continue channel access or instructing the channel state to be idle. In this case, a primitive exchanged between the physical layer and the MAC layer is used. Alternatively, a primitive exchanged between one STA and another STA in the MLD is used. Alternatively, a primitive exchanged between one MAC layer and another MAC layer in the MLD is used.

[0129] According to an embodiment of the present invention, when a STA belonging to an MLD starts receiving a PPDU, other STAs belonging to the MLD should stop channel access. As described above, channel access can be stopped based on the received duration information. However, due to the position of the field containing the duration information or the time required for decoding, there is a time interval between when PPDU reception begins and when the duration information is obtained. Therefore, if a STA accesses a channel and starts transmission during this time, the above-mentioned problem may occur. Therefore, according to one embodiment of the present invention, an STA in an MLD stops channel access when another STA in the MLD starts receiving. Furthermore, after the other STA in the MLD starts receiving, if it is determined that the received frame is not intended for the other STA, the STA resumes channel access.

[0130] FIG. 12 is a diagram showing another example of the Multi-link NAV setting operation according to an embodiment of the present invention.

[0131] FIG. 12 embodies the explanation of the specific method of the embodiment explained in FIG. 11, and duplicate explanations are omitted.

[0132] As described above, based on a frame or PPDU received by a STA belonging to an MLD, other STAs belonging to the same MLD suspend or resume channel access or transmission. In the present invention, suspending channel access or transmission includes operations such as setting (updating) the NAV, determining the channel as busy, or suspending CCA. Resuming channel access or transmission includes operations such as resetting the NAV, canceling the NAV setting, determining the channel as idle, or performing CCA. These operations are hereinafter referred to as suspending and resuming channel access. In the following, it is assumed that STA1 and STA2 belong to the MLD and operate on Link1 and Link2, respectively. In addition, frame and PPDU are used interchangeably to indicate this. In addition, the NAV in this case is the inter-BSS NAV or inter-link NAV, as described in FIG. 11.

[0133] According to an embodiment of the present invention, when STA1 begins to receive a frame, STA2 suspends channel access. Also, when STA1 acquires duration information from the L-SIG, STA2 maintains the suspended state of channel access. In this case, STA2 determines that the suspended state of channel access will last until the end of the frame received by STA1. Also, if STA1 fails to correctly decode the L-SIG (if it is an invalid L-SIG), STA2 resumes channel access.

[0134] STA1 may also have received the TXOP duration and BSS color from the U-SIG of the received frame. If the received BSS color indicates inter-BSS or the BSS color is the BSS color corresponding to STA1, channel access is suspended. In one embodiment, the channel access suspension period is until the end of the received frame. This has the advantage of starting channel access more quickly after the received frame ends. In another embodiment, the channel access suspension period is the TXOP duration. In this case, the suspended channel access period is updated based on the L-SIG. This has the advantage of better protecting the sequence following the received frame.

[0135] Alternatively, STA1 may receive the TXOP duration and BSS color from the U-SIG of the received frame, and the received BSS color may indicate that it is not intra-BSS, or the BSS color may not be the BSS color that corresponds to STA1. Alternatively, STA1 may not be able to successfully decode the U-SIG. In this case, STA2 resumes channel access.

[0136] Alternatively, if the information obtained from the U-SIG of the frame received by STA1 indicates that the frame is not received by STA1, STA2 resumes channel access. For example, if the PHY identifier obtained from the U-SIG is an ID corresponding to a future standard or an unrecognized ID, STA2 resumes channel access.

[0137] Although the case of receiving U-SIG has been described, the same embodiment may be applied to the case of receiving HE PPDU or HE-SIG-A. For example, HE-SIG-A includes TXOP duration and BSS color, and the above-described operations are performed accordingly.

[0138] Also, STA2 may have received the STA-ID from the EHT-SIG of the frame received by STA1. If the received STA-ID is an indicator that STA1 should receive, for example, if the STA-ID indicates STA1, the STA-ID indicates the group to which STA1 belongs, or the STA-ID indicates broadcast, STA2 will continue to suspend channel access.

[0139] Alternatively, STA2 may have received the STA-ID from the EHT-SIG of the frame received by STA1. If the received STA-ID does not correspond to STA1, for example, if the STA-ID does not indicate that it corresponds to STA1, does not indicate the group to which STA1 belongs, or does not indicate broadcast, STA2 resumes channel access. Alternatively, STA2 may resume channel access if STA1 fails to correctly decode the EHT-SIG.

[0140] Although the case of receiving EHT-SIG has been described, the same embodiment may be applied to the case of receiving HE PPDU or HE-SIG-B. For example, HE-SIG-B includes a STA-ID, and the above-described operation is performed accordingly.

[0141] STA2 may also have received the MAC header of the frame received by STA1. If the RA (receiver address) or DA (destination address) included in the received MAC header indicates a value that STA1 should receive, for example, if the RA or DA indicates STA1, indicates a group to which STA1 belongs, or the STA-ID indicates broadcast, STA2 continues to suspend channel access. In this case, the duration of the suspended channel access is based on the duration information included in the received MAC header. More specifically, the duration of the suspended channel access is based on the duration information indicated by the Duration / ID field included in the received MAC header.

[0142] STA2 may also have received the MAC header of the frame received by STA1. If the received MAC header contains an RA or DA that does not correspond to STA1, for example, if RA or DA does not indicate an indication that corresponds to STA1, does not indicate a group to which STA1 belongs, and does not indicate broadcast, STA2 resumes channel access. Alternatively, STA1 may not have received all of the MAC header. For example, STA1 may have failed to receive all of the MPDUs included in the A-MPDU. In this case, STA2 resumes channel access.

[0143] The channel access suspension and resumption described in FIG. 12 operates gradually in the decoding order as STA1 starts receiving and decoding frames (or PPDUs). The decoding order depends on the PPDU frame, frame format, etc. For example, the L-SIG, U-SIG, EHT-SIG, and MAC header are decoded in this order (for EHT PPDUs). Alternatively, the L-SIG, HE-SIG-A, and MAC header are decoded in this order (for HE SU PPDUs and HE TB PPDUs). Alternatively, the L-SIG, HE-SIG-A, HE-SIG-B, and MAC header are decoded in this order (for HE MU PPDUs). Alternatively, the L-SIG and MAC header are decoded in this order (for 11a / g PPDUs).

[0144] According to an embodiment of the present invention, the above-mentioned STA-ID is a value indicating the intended recipient of a PPDU or RU (resource unit). The STA-ID is included in the EHT-SIG field or the HE-SIG-B field. The STA-ID indicates a value corresponding to a single STA. For example, when multiple STAs are included in an MLD, the STA-ID indicates a value corresponding to one of the multiple STAs. The STA-ID is a value based on an AID or a MAC address.

[0145] FIG. 13 is a diagram showing an example of BSS classification and operations based thereon according to an embodiment of the present invention.

[0146] According to one embodiment of the present invention, an STA classifies (or determines) a BSS based on a received frame or a received PPDU. Classifying a BSS includes an operation of determining whether a received frame or a received PPDU corresponds to a BSS to which the STA belongs. Alternatively, classifying a BSS refers to an operation of determining whether a received frame or a received PPDU is transmitted from a BSS to which the STA belongs. Alternatively, classifying a BSS includes an operation of determining whether a received frame or a received PPDU is transmitted from a BSS to which the STA does not belong. Alternatively, classifying a BSS includes an operation of determining to which BSS a received frame or a received PPDU belongs. Alternatively, classifying a BSS refers to an operation of determining from which BSS a received frame or a received PPDU is transmitted. According to one embodiment of the present invention, the BSS to which the STA belongs is referred to as an intra-BSS. Alternatively, a BSS including a BSS to which a classified STA belongs is referred to as an intra-BSS. Also, a BSS that is not an intra-BSS is referred to as an inter-BSS. Or, a BSS that is not an intra-BSS is an inter-BSS or an unclassified BSS. Or, an inter-BSS includes an unclassified BSS. Also, a BSS to which a classified STA does not belong is referred to as an inter-BSS.

[0147] According to one embodiment, if a received frame or a received PPDU is determined to correspond to an intra-BSS or to have been transmitted from an intra-BSS, the received frame or the received PPDU is referred to as an intra-BSS frame or an intra-BSS PPDU, respectively. Also, if a received frame or a received PPDU is determined to correspond to an inter-BSS or to have been transmitted from an inter-BSS, the received frame or the received PPDU is referred to as an inter-BSS frame or an inter-BSS PPDU, respectively. Also, a PPDU including an intra-BSS frame is an intra-BSS PPDU. Also, a PPDU including an inter-BSS frame is an inter-BSS PPDU.

[0148] According to one embodiment of the present invention, a BSS is classified based on one or more BSS classification conditions, for example, the BSS is classified according to whether at least one of the one or more BSS classification conditions is satisfied.

[0149] The BSS classification conditions include a condition based on the BSS color. The BSS color is an identifier for a BSS. The BSS color is included in the PPDU preamble, more specifically, in the signaling field (e.g., the HE-SIG-A field, the U-SIG field, or the VHT-SIG-A field). The BSS color is included in the TXVECTOR transmitted from the MAC layer of the sender to the PHY layer. The BSS color is included in the RXVECTOR transmitted from the PHY layer of the receiver to the MAC layer. The parameters included in the TXVECTOR and RXVECTOR are referred to as the TXVECTOR parameter and the RXVECTOR parameter, respectively. The BSS color is included in the TXVECTOR parameter or the RXVECTOR parameter. The AP notifies the STA of the BSS color set by the AP. According to one embodiment, the BSS is classified based on the BSS color included in the PPDU. If the BSS color included in the PPDU received by the STA is different from the BSS color of the BSS corresponding to the STA, the received PPDU is classified as an inter-BSS PPDU. Alternatively, if the BSS color included in the PPDU received by the STA is different from the BSS color of the BSS corresponding to the STA and its value is not 0, the received PPDU is classified as an inter-BSS PPDU. If the BSS color included in the PPDU received by the STA is the same as the BSS color of the BSS corresponding to the STA, the received PPDU is classified as an intra-BSS PPDU.

[0150] The BSS classification conditions include a condition based on the MAC address. The MAC address is included in the MAC header of the frame. The MAC address may include a receiver address (RA), a transmitter address (TA), a BSSID, a source address (SA), and a destination address (DA). According to one embodiment, the BSS is classified based on the MAC address included in the received frame. If the MAC address included in the received frame is different from the BSSID of the BSS corresponding to the STA, the received frame is classified as an inter-BSS frame. More specifically, if all MAC addresses included in the received frame are different from the BSSID of the BSS corresponding to the STA, the received frame is classified as an inter-BSS frame. Furthermore, if the MAC address included in the received frame is the same as the BSSID of the BSS corresponding to the STA, the received frame is classified as an intra-BSS frame. More specifically, if at least one of the MAC addresses included in the received frame is the same as the BSSID of the BSS corresponding to the STA, the received frame is classified as an intra-BSS frame.

[0151] The corresponding BSS includes a BSS to which the STA is associated, a BSS included in the same multiple BSSID set as the associated BSS, and a BSS included in the same co-hosted BSSID set as the associated BSS. For one or more BSSs included in the same multiple BSSID set or the same co-hosted BSSID set, information about the one or more BSSs is transmitted via one frame.

[0152] The BSS classification conditions include conditions based on the value of the Partial AID field included in the VHT PPDU. The Partial AID field is included in the preamble of the VHT PPDU. The Partial AID field is also included in the VHT-SIG-A field included in the VHT PPDU. According to one embodiment, the Partial AID field indicates part of the BSS color. For example, when the partial BSS color function is used, the Partial AID field indicates part of the BSS color. Or, when the AID assignment rule is used, the Partial AID field indicates part of the BSS color. The AID assignment rule is a method of assigning an AID based on the BSS color. Also, when the Group ID field included in the VHT-SIG-A field of the VHT PPDU is a preset value (for example, when the Group ID field is set to 63), the Partial AID field indicates part of the BSS color. According to one embodiment, if the Partial AID field of a received PPDU indicates part of a BSS color, and the received Partial AID field value is different from the part of the BSS color corresponding to the receiving STA, the received PPDU is classified as an inter-BSS PPDU.

[0153] Furthermore, if the Partial AID field of a received PPDU indicates a portion of a BSS color and the value of the received Partial AID field is the same as the portion of the BSS color corresponding to the receiving STA, the received PPDU is classified as an intra-BSS PPDU. In this case, the portion of the BSS color is 4 LSBs of the BSS color. In another embodiment, the Partial AID field indicates a portion of the BSSID. For example, if the Group ID field included in the VHT-SIG-A field of the VHT PPDU is a preset value (e.g., the Group ID field is set to 0), the Partial AID field indicates a portion of the BSSID. In one embodiment, if the Partial AID field of a received PPDU indicates a portion of a BSSID and the value of the received Partial AID field is different from the portion of the BSSID corresponding to the receiving STA, the received PPDU is classified as an inter-BSS PPDU. In addition, if the BSSID of a received PPDU indicates a portion of a BSS color and the value of the received Partial AID field is the same as the portion of the BSSID corresponding to the receiving STA, the received PPDU is classified as an intra-BSS PPDU. In this case, the part of the BSSID is the 9 MSBs of the BSSID, the Partial AID field value is included in the TXVECTOR parameter PARTIAL_AID or the RXVECTOR parameter PARTIAL_AID, and the Group ID field value is included in the TXVECTOR parameter GROUP_ID or the RXVECTOR parameter GROUP_ID.

[0154] The BSS classification conditions include conditions under which the AP receives PPDUs of a preset condition. For example, the PPDUs of the preset condition include downlink PPDUs. According to one embodiment, the downlink PPDU includes a VHT MU PPDU. Also, the downlink PPDU includes a PPDU in which signaling indicating whether it is an uplink or downlink is set to a preset value. The signaling indicating whether it is an uplink or downlink is included in the signaling field of the EHT PPDU. Alternatively, the signaling indicating whether it is an uplink or downlink is included in the U-SIG. The U-SIG is included in the preamble of the EHT PPDU or a PPDU in accordance with the EHT standard or later.

[0155] In addition, there are cases where a PPDU cannot be classified as an intra-BSS PPDU or an inter-BSS PPDU. For example, if both the above conditions for classification as an intra-BSS PPDU and the conditions for classification as an inter-BSS PPDU are not met, the PPDU cannot be classified as an intra-BSS PPDU or an inter-BSS PPDU.

[0156] In addition, when classifying BSSs, if the classification results based on multiple conditions do not match, the final result is determined based on pre-set conditions. For example, if the results based on the BSS color and the MAC address do not match, the result based on the MAC address takes precedence, or the MAC address result determines the final result. Alternatively, if both the conditions for classification as an intra-BSS PPDU and the conditions for classification as an inter-BSS PPDU are met, the PPDU is classified as an intra-BSS PPDU.

[0157] According to one embodiment of the present invention, a STA performs an operation based on a classified BSS. The operation based on the classified BSS includes an intra-PPDU power save operation. The intra-PPDU power save operation is a power save operation based on a received PPDU. The intra-PPDU power save operation can be performed if a predetermined condition is satisfied. The predetermined condition includes a condition for classifying a PPDU as an intra-BSS PPDU. The predetermined condition also includes a condition that the intended receiver of a received PPDU is not the STA that received the PPDU. For example, if the ID or address included in a PPDU does not correspond to the STA that received the PPDU, the intended receiver of the PPDU is not the STA that received the PPDU. The ID is included in the PPDU preamble. For example, the ID is the STA_ID included in the PPDU preamble. The STA_ID is also included in an HE MU PPDU or EHT PPDU. The address is the MAC address described above. Furthermore, if the signaling indicating uplink or downlink included in the received PPDU indicates uplink, the intended receiver of the PPDU is not the STA that received the PPDU. Also, if the settings of the received PPDU are set to be unsupported by the STA that received the PPDU, the intended receiver of the PPDU is not the STA that received the PPDU. The settings of the received PPDU include the MCS, number of spatial streams, channel width, etc. of the PPDU. Also, if the settings of the received PPDU are unsupported by the STA that received the PPDU, a PHY-RXEND.indication(UnsupportedRate) primitive is received. Also, if the received PPDU is in a preset format, the intended receiver of the PPDU is not the STA that received the PPDU. The preset format includes the TB PPDU. The TB PPDU includes the HE TB PPDU and the EHT TB PPDU.Also, the TB PPDU is a PPDU transmitted in response to a triggering frame. The triggering frame includes a trigger frame. The triggering frame includes a frame containing triggering information. The trigger frame is included in a MAC header, for example, an A-control field. The triggering information or information contained in the trigger frame includes the length of the responding PPDU, the RU used for responding, the PHY configuration used for responding, the MAC configuration, etc. The intra-PPDU power save operation is an operation of entering a doze state until the end of the received PPDU. As another example, if the STA determines that the intended receiver of the received PPDU or frame is not the STA, it suspends reception or decoding of the PPDU or frame.

[0158] The method includes an operation of setting (or updating) a NAV based on the classified BSS. According to one embodiment, a STA operates one or more NAVs. When the STA receives a PPDU or a frame, it sets a NAV corresponding to the classified BSS based on the received PPDU or frame. For example, intra-BSS NAV is a NAV corresponding to an intra-BSS PPDU. Furthermore, basic NAV is a NAV corresponding to a PPDU that is not an intra-BSS PPDU. Alternatively, basic NAV is a NAV corresponding to an inter-BSS PPDU. Furthermore, when setting a NAV based on a received PPDU or a received frame, duration information included in the received PPDU or the received frame is used. The duration information includes a TXOP. TXOP refers to a value included in the TXOP field. The TXOP field is included in the preamble of a PPDU. For example, the TXOP field is included in the HE-SIG-A field included in an HE PPDU. Alternatively, the TXOP field is included in the U-SIG field of an EHT PPDU or a standard PPDU after EHT. Furthermore, the duration information is included in the MAC header. For example, the duration information is included in the Duration / ID field included in the MAC header.

[0159] The classified BSS-based operations include spatial reuse operations. The classified BSS-based operations also include channel access operations. Spatial reuse operations are channel access operations. When a STA receives a PPDU or frame, it performs spatial reuse operations if preset conditions are met. The preset conditions include a condition that the received PPDU or frame corresponds to an inter-BSS. The preset conditions also include a condition that the signal strength of the received PPDU or frame is less than a threshold. For example, the threshold is variable. The threshold is a threshold for the OBSS PD-based spatial reuse operation. The threshold is a value greater than or equal to the CCA threshold. The threshold is a value based on the power to be transmitted. Spatial reuse operations are operations to transmit a PPDU. Spatial reuse operations also include an operation to reset the PHY. For example, an operation to reset the PHY is an operation to issue a PHY-CCARESET.request primitive. In addition, the spatial reuse operation includes an operation of not setting the NAV based on the received PPPDU or the received frame. If a STA performs the spatial reuse operation, the STA transmits a PPDU while the received PPDU or the received frame is being transmitted or received.

[0160] Referring to FIG. 13, there are BSS A and BSS B, but BSS A and BSS B are different BSSs. BSS A and BSS B are inter-BSSs. That is, a PPDU or frame transmitted by a STA associated with BSS A in BSS B is classified as an inter-BSS PPDU or inter-BSS frame. Also, STA1 and STA2 belong to BSS A (or are associated with the AP operating BSS A). STA3 and STA4 belong to BSS B (or are associated with the AP operating BSS B). Referring to FIG. 13, STA1 transmits a PPDU. The PPDU transmitted by STA1 includes information about the BSS. For example, the information about the BSS is information for classifying the BSSs described above. The PPDU transmitted by STA1 also includes duration information.

[0161] STA2 receives the PPDU transmitted by STA1 and classifies the BSS for this PPDU. Since STA2 and STA1 belong to BSS A, the PPDU received by STA2 is classified as an intra-BSS PPDU. The PPDU received by STA2 is either a UL PPDU or a PPDU for which the STA is not an intended receiver. Therefore, according to the above-described embodiment, STA2 performs intra-PPDU power save. Referring to FIG. 13, STA2 enters the doze state until the end of the received PPDU. Furthermore, STA2 sets the NAV based on the duration information included in the received PPDU. Since STA2 has classified the received PPDU as an intra-BSS PPDU, it sets the intra-BSS NAV.

[0162] STA3 receives the PPDU transmitted by STA1 and classifies the BSS for this PPDU. Also, since STA3 and STA1 belong to BSS B and BSS A, respectively, the PPDU received by STA3 is classified as an inter-BSS PPDU. STA3 also sets the NAV based on the duration information included in the received PPDU. Since STA3 classified the received PPDU as an inter-BSS PPDU, it sets the inter-BSS NAV.

[0163] STA4 receives the PPDU transmitted by STA1 and classifies the BSS for this PPDU. Because STA4 and STA1 belong to BSS B and BSS A, respectively, the PPDU received by STA4 is classified as an inter-BSS PPDU. Furthermore, the signal strength of the PPDU received by STA4 is lower than the threshold. Therefore, because the PPDU received by STA4 is classified as an inter-BSS PPDU and the signal strength of the PPDU received by STA4 is lower than the threshold, STA4 performs spatial reuse. Therefore, STA4 performs channel access and backoff procedures and starts transmission. For example, STA4 may start transmission before STA1 has finished transmitting the PPDU.

[0164] FIG. 14 is a diagram illustrating an example of BSS classification based on the U-SIG field according to one embodiment of the present invention.

[0165] According to one embodiment of the present invention, a STA classifies a BSS based on an EHT PPDU or an EHT-standard or later-compliant PPDU. For example, the STA classifies a BSS based on the U-SIG field. As described above, the U-SIG field may be included in the EHT PPDU or an EHT-standard or later-compliant PPDU, or may be included in the preamble of the EHT PPDU or an EHT-standard or later-compliant PPDU. Alternatively, the STA determines whether the STA is an intended receiver of a PPDU based on the EHT PPDU or an EHT-standard or later-compliant PPDU. For example, the STA determines whether the STA is an intended receiver of a PPDU based on the U-SIG field. Operations after classifying a BSS or determining whether the STA is an intended receiver may be the same as those described in FIG. 13 and are omitted in the description of FIG. 14. Also, the description of the PPDU format and the fields included in the PPDU has been omitted. The EHT PPDU or an EHT-standard or later-compliant PPDU includes, in order, an L-STF, an L-LTF, an L-SIG, an RL-SIG, and a U-SIG field.

[0166] According to one embodiment of the present invention, the operation of classifying a BSS or determining whether it is an intended receiver is based on the PHY version field. As described above, the PHY version field is included in the U-SIG field. The PHY version field also serves to indicate the standard to which the PPDU containing the PHY version field applies.

[0167] According to one embodiment, if a PHY version field included in a PPDU received by an STA indicates a value corresponding to a standard that the STA does not support, the STA determines that the PPDU is an inter-BSS PPDU or that the intended receiver of the PPDU is not the STA. Alternatively, if a PHY version field included in a PPDU received by an STA indicates a value corresponding to a standard that the STA has not associated or set up, the STA determines that the PPDU is an inter-BSS PPDU or that the intended receiver of the PPDU is not the STA. This operation is possible because the PHY version field is included in the version intended field.

[0168] For example, if the PHY version field value is greater than the value corresponding to the standard that the STA supports, it is determined to be an unsupported standard. For example, if the PHY version field value corresponding to the EHT standard or EHT PPDU is 0 (000), when an EHT STA receives a PHY version field set to a value greater than 0, it determines that the PPDU including the PHY version field is a PPDU corresponding to an unsupported standard. Also, if the PHY version field received by the STA is set to a value corresponding to a future standard compared to the supported standard, it is determined to be an unsupported standard.

[0169] For example, if the PHY version field included in a PPDU received by an AP indicates a value corresponding to a standard not supported by the AP, the AP determines the PPDU as an inter-BSS PPDU or determines that the intended receiver of the PPDU is not the AP. Alternatively, if the PHY version field included in a PPDU received by an AP indicates a value corresponding to a standard not associated or set up by the AP, the AP determines the PPDU as an inter-BSS PPDU or determines that the intended receiver of the PPDU is not the AP. This is because an AP would not operate on a standard not supported or associated by the AP in a BSS operated by the AP.

[0170] According to one embodiment, the AP can signal the standards it supports, so that STAs receiving this signaling know the standards supported or in use in the BSS. Therefore, STAs can also classify BSSs based on the PHY version field.

[0171] According to one embodiment, if the PHY version field included in a PPDU received by an AP or non-AP STA indicates a value corresponding to an unsupported standard, the AP or non-AP STA determines that the PPDU is an inter-BSS PPDU or that the intended receiver of the PPDU is not itself. Thus, for example, if the BSS color of a PPDU received by a non-AP STA is the same as the BSS color value corresponding to the non-AP STA's BSS, and the PHY version field of the received PPDU indicates a value corresponding to an unsupported standard, the AP or non-AP STA can perform intra-PPDU power save or determine that the STA is not the intended receiver. Determining the intended receiver from the U-SIG field allows for faster determination than checking ID information present after the U-SIG field.

[0172] As described above, BSS classification is performed based on BSS color. However, there is a possibility that the BSS color of a certain BSS may be the same as the BSS color of an OBS (BSS color collision). Or, there is a possibility that the use of the BSS color may be disabled (for example, when the AP instructs the suspension of BSS color use or when the BSS Color Disabled field is set to a preset value). Therefore, it is useful to determine the BSS based on values ​​other than the BSS color.

[0173] According to one embodiment, if the classification based on the BSS color and the classification based on the PHY version field do not match, the PPDU is classified based on the PHY version field or is classified as an inter-BSS PPDU.

[0174] Referring to FIG. 14, there are the EHT standard and the NEXT standard, which is a standard that follows the EHT standard. In addition, there are NEXT STAs and NEXT APs that support the NEXT standard. The NEXT STAs are associated with the NEXT AP. In addition, there are EHT APs that support the EHT standard. In addition, the EHT AP receives a PPDU transmitted by a NEXT STA. The PPDU includes a U-SIG field. For example, the U-SIG field is present after the L-STF, L-LTF, L-SIG, and RL-SIG. In addition, the EHT AP receives a PHY version field value included in the U-SIG. At this time, the received PHY version field value is set to a value corresponding to the NEXT standard. In this case, the EHT AP classifies this PPDU as an inter-BSS PPDU. In addition, the EHT AP determines that it is not the intended receiver of this PPDU. Based on this classification or determination, it performs NAV setting, spatial reuse operations, etc.

[0175] FIG. 15 is a diagram illustrating an example of BSS classification based on the U-SIG field or the EHT field according to one embodiment of the present invention.

[0176] According to one embodiment of the present invention, a STA classifies a BSS based on an EHT PPDU or an EHT-standard or later PPDU. For example, the STA classifies a BSS based on a U-SIG field or an EHT-SIG field. The U-SIG field may be included in an EHT PPDU or an EHT-standard or later PPDU, as described above, or may be included in the preamble of the EHT PPDU or an EHT-standard or later PPDU. The EHT-SIG field is included in the preamble of the EHT PPDU. Alternatively, the STA determines whether the STA is an intended receiver of a PPDU based on the EHT PPDU or an EHT-standard or later PPDU. For example, the STA determines whether the STA is an intended receiver of a PPDU based on the U-SIG field or the EHT-SIG field. Operations after classifying a BSS or determining whether it is an intended receiver may be the same as those described in FIG. 13 and are omitted in the description of FIG. 14. Furthermore, the description of the PPDU format and fields included in the PPDU is omitted from the above description. An EHT PPDU or a PPDU conforming to the EHT standard or later includes the following fields in order: L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and SIG field. In this case, the EHT PPDU includes the EHT-SIG field as the SIG field, and a PPDU conforming to the EHT standard or later includes the SIG field corresponding to each standard as the SIG field.

[0177] According to one embodiment of the present invention, the operation of classifying a BSS or determining whether it is an intended receiver is based on puncturing pattern information. According to one embodiment, the puncturing pattern information is included in the U-SIG field or the EHT-SIG field. For example, the puncturing pattern information is included in both the U-SIG field and the EHT-SIG field. In this embodiment of the present invention, the puncturing pattern information includes information indicating channels to be punctured. The puncturing pattern information also includes channel width (bandwidth) information. The puncturing pattern information also includes RU allocation information.

[0178] The puncturing pattern information indicates information about a channel (subchannel) to be punctured or an RU to be punctured. In the description of the present invention, the term "channel" can be substituted with "subchannel" or "RU." Puncturing a channel or RU means that the channel or RU is not in use. The punctured channel may be located in the middle or at the end of an operating channel. This improves channel utilization and efficiency compared to using only contiguous channels. According to one embodiment, the puncturing pattern is determined for a BSS. For example, the puncturing pattern is determined during association. For example, the puncturing pattern information is included in an Association Response frame or a Reassociation Response frame. Alternatively, the puncturing pattern information is included in a Probe frame or a Beacon frame. In such cases, a PPDU is not transmitted on a channel indicated to be punctured, and it is expected that no PPDU will be transmitted on the channel. According to one embodiment, the puncturing pattern is determined for each PPDU. For example, different puncturing patterns are used for transmission for each PPDU. The puncturing pattern determined for the BSS and the puncturing pattern determined for each PPDU are used together. In this case, for a channel determined to be punctured for the BSS, the PPDU is also punctured and transmitted. According to one embodiment, the puncturing pattern information is in the form of a bitmap. For example, the bitmap contains bits corresponding to channels. If the bit corresponding to a certain channel has a preset value, it is punctured.Also, if a bit corresponding to a certain channel has another preset value, it is not punctured. Also, if it is indicated that it is not punctured, it is indicated that it has been punctured by additional signaling later. For example, if the puncturing pattern information included in the U-SIG indicates that a channel is not punctured, the puncturing pattern information included in the EHT-SIG indicates that it has been punctured. Puncturing determined for each BSS is called static puncturing. Puncturing determined for each PPDU is called dynamic puncturing.

[0179] Also, according to one embodiment, there are channels that are not punctured. For example, a channel that is not always punctured is indicated. For example, an AP may indicate a channel that is not always punctured. Channels that are not always punctured include the primary 20 MHz channel.

[0180] In one embodiment, a STA separates a BSS or determines whether it is an intended receiver based on the result of comparing the puncturing pattern information it received with the channels it expects to puncture. In one embodiment, if the puncturing pattern information obtained from a PPDU received by a STA indicates that a channel it expects to puncture is not punctured, it classifies the PPDU as an inter-BSS PPDU or determines that the STA is not the intended receiver of the PPDU. The channels it expects to puncture are based on the puncturing pattern information it received from the AP. Alternatively, the STA may be the AP that configured and instructed the channels to be punctured in the BSS.

[0181] Alternatively, according to one embodiment, a STA separates a BSS or determines whether it is an intended receiver based on the result of comparing puncturing pattern information received by the STA with channels that are not expected to be punctured. According to one embodiment, if puncturing pattern information obtained from a PPDU received by the STA indicates that a channel that is not expected to be punctured by the STA has been punctured, the STA classifies the PPDU as an inter-BSS PPDU or determines that the STA is not the intended receiver of the PPDU. The channels that are not expected to be punctured by the STA are based on puncturing pattern information instructed to the STA by the AP. Alternatively, the STA may be an AP that has set and instructed channels that are not expected to be punctured in the BSS.

[0182] Referring to FIG. 15, an EHT STA is associated with an EHT AP. The EHT STA also receives puncturing pattern information from the EHT AP. At this time, the puncturing pattern information is information regarding static puncturing. For example, the EHT AP indicates that some of the operating channels are to be punctured. Referring to FIG. 15, the shaded channels are indicated as being punctured. Therefore, these channels are not used in this BSS. The EHT STA also receives a PPDU. The PPDU includes puncturing pattern information. For example, the puncturing pattern information is included in the U-SIG or EHT-SIG field included in the PPDU. At this time, the EHT STA compares the puncturing pattern information included in the PPDU with the puncturing pattern information received from the EHT AP. For example, if a channel indicated as being punctured in the puncturing pattern information received from the EHT AP is not punctured according to the puncturing pattern information included in the PPDU, the EHT STA determines that the PPDU is an inter-BSS PPDU. In this case, the EHT STA also determines that the intended receiver of the PPDU is not the EHT STA. Accordingly, channel access operation, spatial reuse operation, and NAV setting operation are performed. Referring to Figure 15, puncturing pattern information is shown in the form of a bitmap, with each bit corresponding to a 20MHz channel. The bitmap is mapped to channels in frequency order. A bit of 0 in the bitmap indicates no puncturing, and a bit of 1 indicates puncturing. If the puncturing pattern information included in the PPDU indicates 0000000, it indicates that none of the 20MHz channels are punctured.Therefore, in this case, since the channel that is instructed to be punctured according to the puncturing pattern information received from the EHT AP is not punctured according to the puncturing pattern information included in the PPDU, it is determined that the PPDU is an inter-BBS PPDU and that the intended receiver of the PPDU is not the EHT STA.

[0183] FIG. 16 is a diagram illustrating an example of BSS classification based on MLD addresses according to an embodiment of the present invention.

[0184] According to one embodiment of the present invention, an MLD address exists. The MLD address is an address for the MLD. The MLD address is an identifier for the MLD. For example, there is a MAC address for a STA belonging to the MLD, and there is also an address for the MLD. The MLD address is used in the multi-link setup process. The MLD address is included in the MAC header of the frame. More specifically, the MLD address is included in the access field included in the MAC header. In another embodiment, the MLD address is included in a multi-link (ML) element. The ML element is an element related to multi-link setup, multi-link configuration, or multi-link operation. When a multi-link setup request or multi-link setup response is made, the ML element is included in the frame. According to one embodiment, the ML element is included in an association request frame, association response frame, reassociation request frame, reassociation response frame, probe request frame, probe response frame, beacon frame, authentication request frame, authentication response frame, etc. Furthermore, the ML element includes elements common to all multi-link links and elements corresponding to each link. In addition, the ML element includes an operation element and a capabilities element for a multi-link link. In another embodiment, the MLD address is included in an RNR (reduced neighbor report) element. The RNR element includes information about the MLD, information about neighboring APs, information about neighboring BSSs, etc.The RNR element includes information about whether a certain MLD or a certain AP corresponds to the same BSS as the STA transmitting the rNR element or whether they belong to the same MLD.

[0185] According to one embodiment of the present invention, a STA obtains information about the MLD address corresponding to the AP with which the STA is associated. For example, the STA performs multi-link setup and obtains the MLD address of the setup AP. The MLD address corresponding to the AP with which the STA is associated corresponds to the intra-BSS. When the STA performs multi-link setup, the MLD address corresponding to the setup MLD corresponds to the intra-BSS. Alternatively, the STA may have received the MLD address from an RNR element or an ML element. The STA may also determine whether the received MLD address corresponds to an intra-BSS or inter-BSS address. For example, the STA may receive signaling indicating whether the received MLD address corresponds to an intra-BSS or inter-BSS address, and the determination is made based on this signaling. This signaling is included in the RNR element or the ML element. If the MLD address corresponds to an intra-BSS address, the received frame or element containing the MLD address is considered to be an intra-BSS frame. If the MLD address corresponds to an inter-BSS, when a frame or element containing the MLD address is received, it is determined to be an inter-BSS frame.

[0186] Referring to FIG. 16, an EHT STA is associated with an EHT AP. The EHT STA also receives an MLD address corresponding to the EHT AP. In one embodiment, the EHT STA receives the MLD address corresponding to the EHT AP during multi-link setup with the EHT AP. For example, the MLD address is received through the MAC address field included in an RNR element, an ML element, or a management frame. If the EHT STA receives the MLD address corresponding to the EHT AP, it determines the frame including the MLD address as an intra-BSS frame. For example, as shown in FIG. 16, the EHT AP transmits a management frame including an MLD address. For example, the management frame may have been transmitted for an unassociated STA. The management frame also includes the MLD address corresponding to the EHT AP in the MAC header or an element included in the management frame. The EHT STA receives the management frame and classifies it as an intra-BSS frame.

[0187] In another embodiment, the EHT STA receives an address corresponding to the MLD to which the OBSS AP belongs (or an address corresponding to the OBSS AP). For example, the EHT STA receives an address corresponding to the MLD to which the OBSS AP belongs (OBSS AP MLD address) from the EHT AP. For example, the EHT AP includes the OBSS AP MLD address in an RNR element. Alternatively, the EHT STA collects the OBSS AP MLD address by receiving frames, etc., for a certain period of time. If the OBSS AP MLD address is included in a frame or element received by the EHT STA, it is classified as an inter-BSS frame.

[0188] Table 1 below shows an example of a U-SIG content field.

[0189] [Table 1]

[0190] Referring to Table 1, an EHT PPDU or a PPDU conforming to the EHT standard or later includes a U-SIG field. For example, an EHT PPDU or a PPDU conforming to the EHT standard or later includes the L-STF, L-LTF, L-SIG, RL-SIG, and U-SIG fields in that order. Alternatively, the U-SIG field is located immediately after the RL-SIG field. The U-SIG field consists of two OFDM symbols and is jointly encoded. The U-SIG field includes 52 data tones and 4 pilot tones, each 20 MHz apart. The U-SIG field is BPSK modulated.

[0191] Furthermore, the U-SIG field includes both a version independent field and a version dependent field. The version independent field is a version independent portion. In other words, the version independent field is a portion that is included regardless of the standard of the PPDU in which the U-SIG field is included. The version independent field has the same format regardless of the standard of the PPDU in which the U-SIG field is included. For example, each subfield included in the version independent field has the same meaning regardless of the standard of the PPDU in which it is included. Furthermore, each subfield included in the version independent field exists in the same position regardless of the standard of the PPDU in which it is included. Furthermore, each subfield included in the version independent field has the same number of bits (or bit width) regardless of the standard of the PPDU in which it is included.

[0192] Regardless of which standard PPDU it is included in means that it does not matter what PHY version field value is included in the U-SIG field. Regardless of which standard PPDU it is included in means that it does not matter whether it is included in the EHT PPDU or a PPDU after the EHT standard.

[0193] A version dependent field is a part that is version dependent. In other words, a version dependent field is a part that differs depending on the standard of the PPDU in which the U-SIG field is included. A version dependent field has a different format depending on the standard of the PPDU in which the U-SIG field is included. For example, the meaning or position of each subfield (or bit) included in a version dependent field differs depending on the standard of the PPDU in which it is included. "Differing depending on the standard of the PPDU in which it is included" means that it may differ depending on whether the PHY version field value included in the U-SIG field is different. "Differing depending on the standard of the PPDU in which it is included" means that it may differ depending on whether it is included in an EHT PPDU or a PDDU of a later EHT standard.

[0194] According to one embodiment of the present invention, the U-SIG field includes a PHY version field. In one embodiment, the version independent field of the U-SIG field includes a PHY version field. The meaning of the PHY version field is as described above. For example, the PHY version field indicates the standard to which the PPDU including the PHY version field corresponds. The PHY version field also indicates which standard the format and functions of the MAC frame included in the PPDU including the PHY version field correspond to. The PHY version field also indicates the format of the version dependent field of the U-SIG field including the PHY version field. According to one embodiment, the PHY version field is 3 bits. For example, if the PHY version field is set to 000 (binary; 0 in decimal), it indicates the EHT standard.

[0195] According to one embodiment of the present invention, the U-SIG field includes a UL / DL field. In one embodiment, the version independent field of the U-SIG field includes a UL / DL field. The UL / DL field serves to indicate whether a PPDU including the UL / DL field is an uplink or a downlink. Alternatively, the UL / DL field serves to indicate whether a PPDU including the UL / DL field is transmitted by an AP or a non-AP STA. Alternatively, the UL / DL field serves to indicate whether the intended receiver of the PPDU including the UL / DL field is the AP or a non-AP STA. According to one embodiment, the UL / DL field is 1-bit.

[0196] According to one embodiment of the present invention, the U-SIG field includes a Bandwidth field. In one embodiment, the version independent field of the U-SIG field includes a Bandwidth field. The Bandwidth field indicates the bandwidth of the PPDU including the Bandwidth field. In this case, the bandwidth of the PPDU means the maximum bandwidth occupied by the PPDU. For example, the bandwidth of the PPDU means the bandwidth when the PPDU is not punctured. According to one embodiment, the Bandwidth field is 3 bits.

[0197] According to one embodiment of the present invention, the U-SIG field includes a puncturing pattern field. In one embodiment, the version-independent field of the U-SIG field includes a puncturing pattern field. In one embodiment, the version-dependent field of the U-SIG field includes a puncturing pattern field. The puncturing pattern field indicates the above-mentioned puncturing pattern information.

[0198] According to one embodiment of the present invention, the U-SIG field includes a BSS color field. In one embodiment, the version independent field of the U-SIG field includes a BSS color field. The BSS color field includes a BSS color. Alternatively, the BSS color field indicates a BSS color. In this case, the BSS color included in the U-SIG field is the BSS color described above in FIGS. 7 and 13. According to one embodiment, the BSS color is an identifier for a BSS. Referring to FIG. 17, the BSS color field consists of N_B bits. In one embodiment, N_B bits is 6 bits. In another embodiment, N_B is a value greater than 6. For example, N_B is 7, or N_B is 8. Using N_B bits greater than 6 bits improves the BSS classification resolution based on the BSS color compared to using 6 bits for the BSS color. The number of BSS color bits in the HE standard is 6 bits. In another embodiment, N_B is a value smaller than 6, in which case there is an advantage that the U-SIG field further includes content other than the BSS color. As an additional embodiment, the N_B-bit BSS color field referred to in the present invention may be configured as separate fields, such as a 6-bit BSS color 1 field and a (N_B-6)-bit BSS color 2 field, and the embodiment may be applied to such a configuration.

[0199] According to one embodiment of the present invention, the version-dependent field of the U-SIG field includes an Extended BSS color field. The Extended BSS color field includes a BSS color. For example, the Extended BSS color field indicates a BSS color. More specifically, the Extended BSS color field includes an additional BSS color value. Alternatively, the Extended BSS color field includes partial information of the BSS color. Referring to FIG. 17, the Extended BSS color field consists of N_EB bits. According to one embodiment, N_EB is smaller than N_B. That is, the BSS color information included in the version-dependent field uses fewer bits than the BSS color information included in the version-independent field. For example, N_EB is 1 or 2.

[0200] According to one embodiment, the U-SIG field includes both a BSS color field included in a version independent field and an Extended BSS color field included in a version dependent field. In this case, using the Extended BSS color field allows for the use of BSS color with higher resolution than using only the BSS color field included in the version independent field. Also, including part of the BSS color information in the version dependent field allows for the limited signaling resources of the U-SIG field to be flexibly defined and used according to standard functions to be defined later.

[0201] In another embodiment, the U-SIG field includes a BSS color field included in a version independent field. In this case, the U-SIG field does not include an Extended BSS color field included in a version dependent field. In this case, there is an advantage that a BSS color with high resolution can be used for the standard PDDU defined later, compared to using the limited signaling resources of the U-SIG field for the Extended BSS color field.

[0202] According to one embodiment, the BSS color field included in the version independent field is set based on one or more Operation elements. The Operation element is transmitted by the AP. The Operation element is included in a Beacon frame, an Association Response frame, a Reassociation Response frame, a Probe Response frame, etc. The Operation element includes parameters related to the operation of the BSS. The Operation element includes an HE Operation element, an EHT Operation element, etc. The HE Operation element and the EHT Operation element are Operation elements corresponding to the HE standard and the EHT standard, respectively. In more detail, the BSS color field included in the version independent field is set based on the BSS color indicated by the HE Operation element and the BSS color indicated by the EHT Operation element. Alternatively, the BSS color field included in the version independent field is set based on the BSS color set in the HE Operation element and the BSS color set in the EHT Operation element. In this case, setting the BSS color field means setting the TXVECTOR parameter BSS_COLOR described above. Also, similar to the description of the BSS color field, the TXVECTOR parameter BSS_COLOR and the RXVECTOR parameter BSS_COLOR may be composed of BSS_COLOR1, which is represented by 6 bits (having a value from 0 to 63), and BSS_COLOR2, which is represented by (N_B-6) bits (having a value from 0 to (2^(N_B-6)-1)).The BSS color specified by (or set in) the HE Operation element constitutes 6 bits of the BSS color field included in the version independent field, and the BSS color specified by (or set in) the EHT Operation element constitutes (N_B-6) bits of the BSS color field included in the version independent field. This is the case when N_B is greater than 6. If N_B is 6, the BSS color field included in the version independent field can be set using only the BSS color included in the HE Operation element.

[0203] According to one embodiment, the Extended BSS color field included in the version dependent field is set based on one or more Operation elements. The Operation elements have been described above. In more detail, the Extended BSS color field included in the version dependent field is set based on the BSS color indicated by the EHT Operation element. Alternatively, the Extended BSS color field included in the version dependent field is set based on the BSS color set in the EHT Operation element. In this case, setting the BSS color field is equivalent to setting the TXVECTOR parameter BSS_COLOR. In addition to the TXVECTOR parameter BSS_COLOR and the RXVECTOR parameter BSS_COLOR, there is also an EXTENDED_BSS_COLOR parameter. The EXTENDED_BSS_COLOR parameter is represented by N_ET bits. The EXTENDED_BSS_COLOR parameter represents a value between 0 and (2^N_ET-1). When combined with the embodiment of the BSS color field included in the version independent field described above, some bits of the BSS color included in the EHT Operation element are used to set the BSS color field included in the version independent field, and other bits of the BSS color included in the EHT Operation element are used to set the Extended BSS color field included in the version dependent field.

[0204] In the above-described embodiment, the embodiment of setting the BSS color field or the Extended BSS color field also applies to the case of setting the active BSS color.

[0205] Furthermore, the method of using the BSS color field included in the version independent field and the extended BSS color field included in the version dependent field will be described in more detail with reference to the embodiments of other drawings.

[0206] According to one embodiment of the present invention, the U-SIG field includes a TXOP field. In one embodiment, the version independent field of the U-SIG field includes a TXOP field. The TXOP field includes a TXOP. TXOP is the above-mentioned TXOP, or TXOP duration, or duration information, or the TXVECTOR parameter TXOP_DURATION, or the RXVECTOR parameter TXOP_DURATION, or a value used to set NAV. Alternatively, the TXOP field indicates a TXOP. Referring to FIG. 17, the TXOP field consists of N_T bits. According to one embodiment, N_T bits is 7 bits. According to another embodiment, N_T is a value greater than 7. For example, N_T is 8, or N_T is 9. Using N_T bits greater than 7 bits can increase the resolution or range of the duration information indicated by the TXOP. The number of TXOP bits in the HE standard is 7 bits. In another embodiment, N_T is a value smaller than 7, in which case there is an advantage that the U-SIG field further includes content other than TXOP. As an additional embodiment, the N_T-bit TXOP field referred to in the present invention may be configured as separate fields, such as a 7-bit TXOP 1 field and an (N_T-7)-bit TXOP 2 field, and the embodiment may be applied to such a configuration.

[0207] According to one embodiment of the present invention, the version dependent field of the U-SIG field includes an Extended TXOP field. The Extended TXOP field includes a TXOP. For example, the Extended TXOP field indicates a TXOP. More specifically, the Extended TXOP field includes an additional TXOP value. Alternatively, the Extended TXOP field includes partial information of the TXOP. Alternatively, the Extended TXOP field includes information correcting the TXOP. Referring to FIG. 17, the Extended TXOP field consists of N_ET bits. According to one embodiment, N_ET is smaller than N_T. That is, the TXOP information included in the version dependent field uses fewer bits than the TXOP information included in the version independent field. For example, N_ET is 1 or 2.

[0208] According to one embodiment, the U-SIG field includes both the TXOP field included in the version independent field and the Extended TXOP field included in the version dependent field. In this case, by using the Extended TXOP field, it is possible to use a TXOP with higher resolution or a wider range than by using only the TXOP field included in the version independent field. In addition, by including some of the additional TXOP information in the version dependent field, the limited signaling resources of the U-SIG field can be flexibly defined and used according to standard functions to be defined later.

[0209] In another embodiment, the U-SIG field includes the TXOP field included in the version independent field. In this case, the U-SIG field does not include the Extended TXOP field included in the version dependent field. In this case, there is an advantage that a TXOP with higher resolution or a wider range of indication can be used for the standard PDDU defined later than when the limited signaling resources of the U-SIG field are used for the Extended TXOP field.

[0210] The method of using the TXOP field included in the version independent field and the Extended TXOP field included in the version dependent field will be described in more detail with reference to the embodiments of other drawings.

[0211] According to one embodiment of the present invention, if a received PHY version field is set to a preset value, the STA ignores information included in a U-SIG field including the PHY version field. Alternatively, if the PHY version field is set to a preset value, the STA ignores information included in a version independent field including the PHY version field. The preset value is a value in which all bits are set to 1. If the PHY version field is 3 bits, the preset value is 7. Alternatively, if the PHY version field is set to a preset value, it indicates the presence of a PHY version field different from the PHY version field. Alternatively, if the PHY version field is set to a preset value, the format of the U-SIG field or the version independent field may be different. If the STA ignores information included in a received U-SIG field, it ignores or suspends decoding of a PPDU including the U-SIG field. Also, if the STA ignores information included in a received U-SIG field, it does not update its NAV. Also, if the STA ignores information included in a received U-SIG field, it does not perform BSS classification or concludes that BSS classification is not possible.

[0212] The PHY version field has a limited number of PHY versions that can be signaled. Therefore, if there are more PHY versions than the limited number, a method for indicating them is required. Therefore, the PHY version field is set to a preset value and a U-SIG with a different configuration is used. Alternatively, the U-SIG field includes a version independent field that has the same format regardless of the PHY version. If a design error occurs, the above operation is performed to prevent an older standard STA from malfunctioning by seeing the version independent field corresponding to the older standard.

[0213] FIG. 17 is a diagram illustrating an example of how an extended BSS color field is used in accordance with an embodiment of the present invention.

[0214] Referring to FIG. 17, the BSS is classified using a BSS color field included in the PPDU.

[0215] In detail, as described above, BSS classification is performed based on the BSS color. Also, in this embodiment, the above-mentioned BSS color information is used, and the above-mentioned content is omitted.

[0216] According to one embodiment of the present invention, a STA classifies a BSS based on multiple BSS color information included in a PPDU received by the STA. For example, if multiple BSS color information included in a PPDU received by the STA matches multiple BSS color information corresponding to the STA, the PPDU is classified as an intra-BSS PPDU. Furthermore, if at least one of the multiple BSS color information included in a PPDU received by the STA does not match the BSS color information corresponding to the STA, the PPDU is classified as an inter-BSS PPDU. For example, multiple BSS color information refers to the BSS color included in the version independent field and the BSS color included in the version dependent field. Alternatively, multiple BSS color information refers to the BSS color 1 field included in the version independent field and the BSS color 2 field included in the version dependent field. Therefore, for example, a BSS is classified based on the BSS color included in the version independent field and the BSS color included in the version dependent field included in the PPDU received by the STA. Alternatively, a BSS is classified based on the BSS color 1 included in the version independent field and the BSS color 2 included in the version dependent field included in the PPDU received by the STA.

[0217] According to one embodiment of the present invention, a STA classifies a BSS based on the BSS color included in the version independent field and the BSS color included in the version dependent field included in a received PPDU only if the received PPDU corresponds to the standard of the STA or a standard prior to the STA's standard. The standard of the received PPDU is determined based on the PHY version field. Therefore, for example, if an EHT STA receives an EHT PPDU, it classifies the BSS based on the BSS color included in the version independent field and the BSS color included in the version dependent field. Also, if an EHT STA receives a PPDU of the NEXT standard, it does not perform the operation of classifying the BSS based on the BSS color included in the version independent field and the BSS color included in the version dependent field. If a NEXT STA receives a PPDU of the NEXT standard or a standard prior to the NEXT standard, it classifies the BSS based on the BSS color included in the version independent field and the BSS color included in the version dependent field.

[0218] According to one embodiment of the present invention, a STA classifies a BSS based only on the BSS color included in the version independent field of a received PPDU (not based on the BSS color included in the version dependent field) only if the received PPDU corresponds to a standard subsequent to the standard of the STA. The standard corresponding to the received PPDU is determined based on the PHY version field. Therefore, for example, if an EHT STA receives a PPDU of the NEXT standard, it classifies the BSS based on the BSS color included in the version independent field. If a NEXT STA receives a PPDU of the NEXT standard or later, it classifies the BSS based on the BSS color included in the version independent field.

[0219] As described above, when a STA classifies the BSS of a received PPDU, it may perform other operations based on the standard corresponding to the received PPDU. For example, as described above, when a STA classifies the BSS of a received PPDU, it may perform operations based on other numbers or other bits of BSS color information based on the standard corresponding to the received PPDU.

[0220] Referring to Figure 17, an EHT STA receives a PPDU. For example, the PPDU includes a U-SIG field. If the PHY version field included in the U-SIG field indicates the EHT standard, the BSS is classified based on the BSS color included in the version independent field and the Extended BSS color included in the version dependent field. If at least one of the BSS color included in the version independent field and the Extended BSS color included in the version dependent field is different from the value corresponding to the BSS of the receiving STA, the received PPDU is classified as an inter-BSS PPDU. If both the BSS color included in the version independent field and the Extended BSS color included in the version dependent field are the same as the value corresponding to the BSS of the receiving STA, the received PPDU is classified as an intra-BSS PPDU.

[0221] If the PHY version field included in the U-SIG field indicates a standard subsequent to the EHT standard, the BSS is classified based on the BSS color included in the version independent field. In this case, the BSS is classified regardless of the BSS color included in the version dependent field. If the BSS color included in the version independent field is different from the value corresponding to the BSS of the receiving STA, the received PPDU is classified as an inter-BSS PPDU. If the BSS color included in the version independent field is the same as the value corresponding to the BSS of the receiving STA, the received PPDU is classified as an intra-BSS PPDU.

[0222] According to one embodiment of the present invention, if the BSS color field included in the version independent field indicates no significance, it is determined that the Extended BSS color field included in the version dependent field also indicates no significance. If the BSS color field indicates no significance, the BSS color field is set to a preset value. For example, the preset value is 0. Also, if the BSS color field or the Extended BSS color field indicates no significance, no BSS classification operation is performed based on it.

[0223] FIG. 18 is a diagram illustrating an example of how an extended TXOP field is used according to one embodiment of the present invention.

[0224] As described above, NAV is set based on TXOP. Alternatively, channel access is based on TXOP. More specifically, channel access is restricted to a period based on TXOP. The above description of TXOP is omitted. TXOP is the above-mentioned TXOP, or TXOP duration, or duration information, or TXVECTOR parameter TXOP_DURATION, or RXVECTOR parameter TXOP_DURATION, or a value used to set NAV.

[0225] According to one embodiment of the present invention, a STA determines (or sets) a TXOP based on multiple TXOPr information included in a received PPDU. By determining the TXOP, the STA performs the above-described TXOP-based operation. That is, the TXOP is determined based on multiple TXOP information, and a NAV is set or channel access is performed based on the determined TXOP. For example, multiple TXOP information refers to a TXOPr included in a version independent field and a TXOP included in a version dependent field. Therefore, for example, the STA determines a TXOP based on a TXOP included in a version independent field and a TXOP included in a version dependent field included in a received PPDU.

[0226] According to one embodiment of the present invention, a STA determines a TXOP based on the TXOP included in the version independent field and the TXOP included in the version dependent field included in the received PPDU only if the received PPDU corresponds to the standard of the STA or a standard prior to the STA's standard. The standard of the received PPDU is determined based on the PHY version field. Therefore, for example, when an EHT STA receives an EHT PPDU, it determines a TXOP based on the TXOPr included in the version independent field and the TXOP included in the version dependent field. Also, when an EHT STA receives a PPDU of the NEXT standard, it does not determine a TXOP based on the TXOPr included in the version independent field and the TXOP included in the version dependent field. When a NEXT STA receives a PPDU of the NEXT standard or a standard prior to the NEXT standard, it determines a TXOP based on the TXOP included in the version independent field and the TXOP included in the version dependent field.

[0227] According to one embodiment of the present invention, a STA determines a TXOP based solely on the TXOP included in the version independent field of a received PPDU (not based on the TXOP included in the version dependent field) only if the received PPDU corresponds to a standard later than the standard of the STA. The standard of the received PPDU is determined based on the PHY version field. Thus, for example, if an EHT STA receives a PPDU of the NEXT standard, it determines the TXOP based on the TXOP included in the version independent field. If a NEXT STA receives a PPDU of the NEXT standard or later, it determines the TXOP based on the TXOP included in the version independent field.

[0228] As described above, when a STA determines the TXOP of a received PPDU, it performs other operations based on the standard corresponding to the received PPDU. For example, as described above, when a STA determines the TXOP from a received PPDU, it performs operations based on other numbers or bits of TXOP information based on the standard corresponding to the received PPDU. In this case, the TXOP obtained from the received PPDU is obtained from the preamble included in the received PPDU. More specifically, the TXOP obtained from the received PPDU is obtained from the U-SIG field included in the received PPDU.

[0229] If duration information is received from the MAC frame included in the received PPDU, the operation based on the TXOP information included in the preamble of the received PPDU is not performed. Instead, the operation based on the duration information received from the MAC frame is performed.

[0230] Referring to Figure 18, an EHT STA receives a PPDU. For example, the PPDU includes a U-SIG field. If the PHY version field included in the U-SIG field indicates the EHT standard, the EHT STA determines a TXOP based on the TXOP included in the version independent field and the extended TXOP included in the version dependent field. At this time, the EHT STA sets a NAV based on the determined TXOP or performs a channel access operation (e.g., channel access or no transmission).

[0231] If the PHY version field included in the U-SIG field indicates a standard subsequent to the EHT standard, the TXOP is determined based on the TXOP included in the version independent field. In this case, the TXOP is determined regardless of the TXOP included in the version dependent field. In this case, the NAV is set based on the determined TXOP, or a channel access operation (e.g., channel access or no transmission) is performed.

[0232] According to one embodiment of the present invention, if the TXOP field included in the version independent field indicates meaningless, it is determined that the Extended TXOP field included in the version dependent field also indicates meaningless. If the TXOP field indicates meaningless, the TXOP field is set to a preset value. For example, the preset value is UNSPECIFIED. Alternatively, the preset value is a value in which all bits of the field are set to 1. Furthermore, if the TXOP field or the Extended TXOP field indicates meaningless, no NAV setting or channel access operation based on it is performed.

[0233] The TXOP is determined based on multiple TXOP information. For the description of the TXOP or multiple TXOP information, please refer to the above-mentioned embodiment, and the description is omitted in this embodiment. Determining the TXOP is determining the TXVECTOR parameter TXOP_DURATION or the RXVECTOR parameter TXOP_DURATION.

[0234] Multiple TXOP information includes a TXOP field included in a version independent field and an Extended TXOP field included in a version dependent field. According to one embodiment of the present invention, the TXOP is determined by adding a value based on the TXOP field included in the version independent field and a value based on the Extended TXOP field included in the version dependent field. This is an operation performed when receiving TXOP information. Alternatively, the TXOP is determined by subtracting a value based on the Extended TXOP field included in the version dependent field from a value based on the TXOP field included in the version independent field.

[0235] The following Equation 4 shows an example of a method for calculating TXOP_DURATION, which is an RXVECTOR parameter.

[0236]

number

[0237] Referring to Equation 4, the value based on the TXOP field included in the version independent field is (value based on TXOP), and the value based on the Extended TXOP field included in the version dependent field is (value based on Extended TXOP).

[0238] The TXOP field included in the version independent field is also included in the PPDU of other standards, so STAs that only support older standards should determine the TXOP based on the TXOP field included in the version independent field. Therefore, the TXOP is determined based on the TXOP field included in the version independent field, and the Extended TXOP field included in the version dependent field is used as an auxiliary. For example, as described in FIG. 18, the TXOP field included in the version independent field and the Extended TXOP field included in the version dependent field are used according to the embodiment. For example, the Extended TXOP field included in the version dependent field is a value that corrects the value based on the TXOP field included in the version independent field. For example, the value based on the Extended TXOP field included in the version dependent field is a value smaller than the granularity (resolution) of the TXOP. The value based on the Extended TXOP field included in the version dependent field is a value smaller than the granularity indicated by the TXOP field included in the version independent field.

[0239] According to one embodiment, the value based on the Extended TXOP field is a value based on the granularity of the TXOP. Referring to Equation 4, the value based on the Extended TXOP field is determined as follows: This is the operation performed when receiving TXOP information.

[0240]

number

[0241] In Equation 5, N represents the number of bits in the Extended TXOP field.

[0242] The granularity is the granularity of the TXOP. Alternatively, the granularity is the granularity indicated by the TXOP field included in the version independent field. Alternatively, the granularity is indicated by some bits of the TXOP field included in the version independent field. If there are two types of granularity, the granularity is indicated by one bit that is part of the TXOP field included in the version independent field. If there are two types of granularity, the granularity is a value such as 8us or 128us. If there are four types of granularity, the granularity is indicated by two bits that are part of the TXOP field included in the version independent field. If there are four types of granularity, the granularity is a value such as 8us, 32us, 64us, or 128us. Alternatively, the granularity is a pre-configured value. In such cases, signaling to indicate the granularity is unnecessary. For example, the granularity is 8us.

[0243] Also, extendedTXOP is the value indicated by the Extended TXOP field.

[0244] Therefore, for example, if the Extended TXOP field consists of 2 bits and the TXOP (e.g., the TXOP indicated by the TXOP field included in the version independent field) is represented in 128us units, the value of the Extended TXOP field has values ​​from 0 to 3 (00, 01, 10, 11), and the corresponding values ​​(value based on Extended TXOP) are 0, 32, 64, and 96us, respectively.

[0245] Also, when setting or sending the TXVECTOR parameter, the Extended TXOP field is set as follows. This is the operation performed when sending TXOP information. For example, it is set based on the value based on TXOP_DURATION divided by the above-mentioned (granularity / 2^N). More specifically, it is set by flooring or ceilinging the value based on TXOP_DURATION divided by the above-mentioned (granularity / 2^N). Also, the value based on TXOP_DURATION is the value obtained by subtracting (the minimum value indicated by the granularity of the currently hit TXOP) from TXOP_DURATION. For example, if a value of 512 us or more is indicated with a granularity of 128 us, the value based on TXOP_DURATION is (TXOP_DURATION-512). Also, if the Extended TXOP field consists of 2 bits and the TXOP (for example, the TXOP indicated by the TXOP field included in the version independent field) is indicated in 128 us units, the Extended TXOP field is based on (value based on TXOP_DURATION) / (128 / 4). For example, in this case, the Extended TXOP field is floor((value based on TXOP_DURATION) / (128 / 4)).

[0246] Also, the value based on the TXOP field included in the version independent field is as described in FIG.

[0247] According to one embodiment, the Extended TXOP field included in the version dependent field is used when the granularity of the TXOP is equal to or greater than a preset value. For example, the Extended TXOP field included in the version dependent field is used when the granularity of the TXOP indicated by the TXOP field included in the version independent field is equal to or greater than a preset value. This is because if the granularity is a small value, a high resolution value is indicated without correction for the TXOP. For example, if the granularity is 128us or greater, the Extended TXOP field included in the version dependent field is used.

[0248] The value based on the TXOP field included in the version independent field is determined by the following Equation 6.

[0249]

number

[0250] For the description of TXOP or multiple TXOP information, please refer to the above-mentioned embodiment, and the description thereof will be omitted in this embodiment. Determining TXOP is determining the TXVECTOR parameter TXOP_DURATION or the RXVECTOR parameter TXOP_DURATION.

[0251] According to one embodiment, the TXOP determination method described in Equation 3 is used to determine the TXOP based only on the TXOP field included in the version independent field. For example, if the U-SIG field does not include the Extended TXOP field included in the version dependent field, the TXOP is determined based only on the TXOP field included in the version independent field. Alternatively, as described in FIG. 19, if the version indicated by the U-SIG field corresponds to a standard that does not apply to the STA receiving the PPDU (or an unrecognized standard or a future standard), the TXOP is determined based only on the TXOP field included in the version independent field.

[0252] According to another embodiment, the TXOP determination method described in Equation 3 is used when determining a TXOP based on the TXOP field included in the version independent field and the extended TXOP field included in the version dependent field, as described in Figures 17 and 18. For example, the TXOP determination method described in Figure 21 is used when determining a value based on the TXOP field included in the version independent field, when determining a TXOP based on the TXOP field included in the version independent field and the extended TXOP field included in the version dependent field, as described in Figures 17 and 18. That is, for example, the TXOP determination method described in Figure 21 determines the value (value based on TXOP) described in Figure 20.

[0253] In the present invention, a TXOP based on a TXOP field included in a version independent field is referred to as a value based on TXOP.

[0254] According to one embodiment of the present invention, (value based on TXOP) is based on the offset, granularity, and TXOP field value. This is an operation performed when receiving TXOP information. Referring to FIG. 21, (value based on TXOP) is based on the offset, granularity, and pTXOP. For example, (value based on TXOP) is determined based on the offset and (the value indicated by the TXOP field). For example, (value based on TXOP) is the sum of the offset and (the value indicated by the TXOP field). (The value indicated by the TXOP field) is based on pTXOP. Also, pTXOP is a value indicated by some bits of the TXOP field. For example, pTXOP is a value indicated by bits in the TXOP field excluding the bit indicating granularity. Also, pTXOP is a value obtained by converting some bits of the TXOP field to a decimal number. Also, (the value indicated by the TXOP field) is based on granularity. Granularity is indicated by some bits of the TXOP field. Granularity is indicated by N_G bits of the TXOP field. For example, granularity is indicated by N_G LSBs of the TXOP field. Alternatively, the TXOP field is N_T bits. In this case, pTXOP is the value indicated by the bits (N_T-N_G bits) in the TXOP field excluding the bit indicating granularity. In the present invention, the N_T-N_G value is indicated as N_pTXOP. For example, the TXOP field may be 7 bits, and BO (LSB) may indicate granularity. In this case, the value indicated by bits B1 to B6 of the TXOP field is pTXOP. For example, if bits B1 to B6 are all set to 1, pTXOP is 63. If bits B1 to B6 are all set to 1 except for bit B3 (B3 is set to 0), pTXOP is 59.

[0255] Granularity is specified by some of the LSB bits of the TXOP field. Granularity is a power of 2 value. For example, granularity indicates 4, 8, 16, 32, 64, 128 us, etc. For example, granularity is specified by one bit of the TXOP field. For example, one bit of the TXOP field indicates a granularity of 8 us or 128 us. As another example, granularity is specified by two bits of the TXOP field. For example, two bits of the TXOP field indicate a granularity of 4, 8, 32, 128 us. Or, two bits of the TXOP field indicate a granularity of 8, 32, 64, 128 us. Or, two bits of the TXOP field indicate a granularity of 8, 16, 32, 128 us. Or, two bits of the TXOP field indicate a granularity of 8, 16, 32, 64 us.

[0256] For example, (the value indicated by the TXOP field) is the product of granularity and pTXOP.

[0257] Also, offset is a value based on (a granularity with a value different from the current granularity). Also, offset is a value based on the maximum value of pTXOP. For example, offset is based on the value obtained by multiplying (a granularity with a value different from the current granularity) by (a value based on the maximum value of pTXOP). Also, (a granularity with a value different from the current granularity) is a possible granularity smaller than the current granularity. For example, offset is based on the value obtained by adding (a granularity with a value different from the current granularity) by (a value based on the maximum value of pTXOP). If (a value based on the maximum value of pTXOP) is constant, offset may also be based on the value obtained by adding (a granularity with a value different from the current granularity) and multiplying it by (a value based on the maximum value of pTXOP).

[0258] Also, the value based on the maximum pTXOP is 2^N_pTXOP value. Alternatively, the value based on the maximum pTXOP is the maximum pTXOP plus the current granularity. For example, if N_pTXOP is 6, the value based on the maximum pTXOP is 64.

[0259] Referring to Equation 3, offset is based on the sum of (possible granularities smaller than the current granularity) multiplied by (2^N_pTXOP). If there is no (possible granularity smaller than the current granularity), offset is 0. For example, if there are two possible granularities for TXOP, 8 and 128us, and the current granularity is 8us, offset is 0. Also, if there are two possible granularities for TXOP, 8 and 128us, and the current granularity is 128us, offset is 8*(2^N_pTXOP).

[0260] As another example, if the TXOP's possible granularity is 8, 32, 64, and 128us and the current granularity is 8us, the offset is 0. If the TXOP's possible granularity is 8, 32, 64, and 128us and the current granularity is 32us, the offset is (8)*(2^N_pTXOP). If the TXOP's possible granularity is 8, 32, 64, and 128us and the current granularity is 64us, the offset is (8+32)*(2^N_pTXOP). As another example, if the TXOP's possible granularity is 8, 32, 64, and 128us and the current granularity is 128us, the offset is (8+32+64)*(2^N_pTXOP).

[0261] As another example, if the granularity available for a TXOP is 4, 8, 32, and 128 us and the current granularity is 4 us, the offset is 0. If the granularity available for a TXOP is 4, 8, 32, and 128 us and the current granularity is 8 us, the offset is (4) * (2^N_pTXOP). If the granularity available for a TXOP is 4, 8, 32, and 128 us and the current granularity is 32 us, the offset is (4 + 8) * (2^N_pTXOP). As another example, if the granularity available for a TXOP is 4, 8, 32, and 128 us and the current granularity is 128 us, the offset is (4 + 8 + 32) * (2^N_pTXOP).

[0262] Also, N_pTXOP is a value equal to or greater than 6. That is, six or more preset bits in the TXOP field indicate pTXOP. For example, six, seven, eight, nine, ten, or eleven preset bits in the TXOP field indicate pTXOP.

[0263] Also, when setting or sending the TXVECTOR parameter, the TXOP field is set as follows. This is the operation performed when sending TXOP information. For example, it is set based on the value obtained by dividing the value based on TXOP_DURATION by the above-mentioned granularity. More specifically, it is set by flooring or ceilinging the value obtained by dividing the value based on TXOP_DURATION by the above-mentioned granularity. For example, N_pTXOP bits indicating pTXOP are set based on the value obtained by dividing the value based on TXOP_DURATION by the above-mentioned granularity. Also, the value based on TXOP_DURATION is the value obtained by subtracting the sum of (a possible granularity smaller than the current granularity) multiplied by (2^N_pTXOP) from TXOP_DURATION.

[0264] For example, let the possible granularity values ​​be G_1, G_2, ..., G_(N-2), G_(N-1), G_N, from smallest to largest. If TXOP_DURATION is greater than or equal to (G_1+G_2+...+G_(N-1)*2^N_pTXOPs), then the value based on TXOP_DURATION is as follows:

[0265] (Value based on TXOP_DURATION)=TXOP_DURATION-{(G_1+G_2+…+G_(N-1))*2^N_pTXOP}

[0266] Also, if TXOP_DURATION is greater than or equal to (G_1+G_2+...+G_(N-2)*2^N_pTXOP) and less than (G_1+G_2+...+G_(N-1)*2^N_pTXOP), the value based on TXOP_DURATION is as follows:

[0267] (Value based on TXOP_DURATION)=TXOP_DURATION-{(G_1+G_2+…+G_(N-2))*2^N_pTXOP}

[0268] Also, if TXOP_DURATION is greater than or equal to (G_1)*2^N_pTXOP and less than (G_1+G_2)*2^N_pTXOP, the value based on TXOP_DURATION is as follows:

[0269] (Value based on TXOP_DURATION)=TXOP_DURATION-{(G_1)*2^N_pTXOP}

[0270] Also, if TXOP_DURATION is less than (G_1)*2^N_pTXOP, the value based on TXOP_DURATION is as follows:

[0271] (value based on TXOP_DURATION)=TXOP_DURATION

[0272] According to this rule, a value based on TXOP_DURATION is set depending on the range of TXOP_DURATION.

[0273] More specifically, if there are four possible granularity values, the smallest granularity is G_1, G_2, G_3, and G_4. For example, G_1, G_2, G_3, and G_4 indicate granularities of 4, 8, 32, and 128 us, respectively. Alternatively, G_1, G_2, G_3, and G_4 indicate granularities of 8, 32, 64, and 128 us, respectively. Alternatively, G_1, G_2, G_3, and G_4 indicate granularities of 8, 16, 32, and 128 us, respectively. Alternatively, G_1, G_2, G_3, and G_4 indicate granularities of 8, 16, 32, and 64 us, respectively. In this case, if TXOP_DURATION is greater than or equal to (G_1+G_2+G_3)*2^N_pTXOPs, the value based on TXOP_DURATION is as follows:

[0274] (Value based on TXOP_DURATION)=TXOP_DURATION-{(G_1+G_2+…+G_3)*2^N_pTXOP}

[0275] Also, if TXOP_DURATION is greater than or equal to (G_1+G_2)*2^N_pTXOP and less than (G_1+G_2+G_3)*2^N_pTXOP, the value based on TXOP_DURATION is as follows:

[0276] (Value based on TXOP_DURATION)=TXOP_DURATION-{(G_1+G_2)*2^N_pTXOP}

[0277] Also, if TXOP_DURATION is greater than or equal to (G_1)*2^N_pTXOP and less than (G_1+G_2)*2^N_pTXOP, the value based on TXOP_DURATION is as follows:

[0278] (Value based on TXOP_DURATION)=TXOP_DURATION-{(G_1)*2^N_pTXOP}

[0279] Also, if TXOP_DURATION is less than (G_1)*2^N_pTXOP, the value based on TXOP_DURATION is as follows:

[0280] (value based on TXOP_DURATION)=TXOP_DURATION

[0281] More specifically, if there are two possible granularity values, the smaller granularity is G_1 and G_2. For example, G_1 and G_2 are 8 and 128 us, respectively. In this case, if TXOP_DURATION is greater than or equal to (G_1)*2^N_pTXOP, the value based on TXOP_DURATION is as follows:

[0282] (Value based on TXOP_DURATION)=TXOP_DURATION-{(G_1)*2^N_pTXOP}

[0283] Also, if TXOP_DURATION is less than (G_1)*2^N_pTXOP, the value based on TXOP_DURATION is as follows:

[0284] (value based on TXOP_DURATION)=TXOP_DURATION

[0285] FIG. 19 is a diagram illustrating an example of a BSS classification method according to an embodiment of the present invention.

[0286] As described in the previous embodiment, the BSSs are classified based on the received BSSs. In this embodiment, the method for classifying the BSSs based on the BSS color and the operation based on the classified BSSs will not be described.

[0287] According to one embodiment of the present invention, a STA receives multiple BSS color information or multiple BSS color fields. For example, if a STA receives multiple PPDUs, it receives multiple BSS color information. In one embodiment, the STA receives the BSS color field included in the U-SIG field and the BSS color field included in the HE-SIG-A field. Alternatively, the STA receives the BSS color field included in the U-SIG field included in PPDU1 and the BSS color field included in PPDU2. In addition, the BSS color information received from PPDU1 and PPDU2 may be different. For example, as described in FIG. 18, the BSS color information included in the version dependent field may or may not be received.

[0288] In addition, when a STA receives an A-PPDU (aggregated PPDU), it means receiving multiple PPDUs. For example, an AP receives an A-PPDU. For example, the AP receives an A-PPDU triggered (solicited) by the AP. Or, the AP receives an A-PPDU transmitted by another BSS.

[0289] According to one embodiment of the present invention, if a STA receives multiple BSS color information, the BSS classification results based on the multiple BSS color information may not match. For example, received BSS color information 1 indicates an intra-BSS PPDU, and received BSS color information 2 indicates an inter-BSS PPDU. According to one embodiment of the present invention, in this case, the STA classifies the BSS based on a preset result. For example, in this case, the STA classifies the BSS as an inter-BSS PPDU. Alternatively, in this case, the STA classifies the BSS based on the BSS color information that uses the most bits of the multiple BSS color information received by the STA. For example, if there is BSS classification 1 based on received BSS color information 1 and BSS classification 2 based on received BSS color information 2, if the number of bits of BSS color information 2 is greater than that of BSS color information 1, the STA classifies the BSS as BSS classification 2. Therefore, the STA performs the same operation on a PPDU containing BSS color information 1 as it does when it receives an inter-BSS PPDU. For example, the STA may use spatial reuse operation without configuring intra-BSS NAV.

[0290] Also, if there are BSS classification results based on the BSS color information included in the U-SIG field and BSS classification results based on the MAC address, the BSS classification result based on the MAC address is used as the final result.

[0291] Referring to Figure 22, a PPDU including a U-SIG field and an HE PPDU are transmitted together and received by one STA. The BSS color included in the U-SIG field is N_B bits, and the BSS color included in the HE-SIG-A field is 6 bits. The PPDU is classified as an inter-BSS PPDU based on the BSS color included in the U-SIG field. The PPDU is classified as an intra-BSS PPDU based on the BSS color included in the HE-SIG-A field. In this case, the PPDU is finally determined to be an inter-BSS PPDU because N_B is greater than 6. Therefore, the intra-BSS NAV is not configured based on the BSS color included in the HE-SIG-A field.

[0292] According to one embodiment of the present invention, a STA reports a BSS color collision, for example, to its associated AP. A BSS color collision occurs when the same BSS color as the BSS color corresponding to the BSS to which the STA is associated exists in another nearby BSS. For example, if a STA receives a PPDU from an inter-BSS that uses the same BSS color value as the BSS color corresponding to the BSS to which the STA is associated as the BSS color, the STA reports a BSS color collision. According to one embodiment of the present invention, separate signaling is provided to indicate whether a BSS color collision has occurred for a 6-bit BSS color and whether a BSS color collision has occurred for a BSS color with a number of bits other than 6. For example, separate signaling is provided to indicate whether a BSS color collision has occurred for a 6-bit BSS color and whether a BSS color collision has occurred for a part of a BSS color other than the 6-bit BSS color for a BSS color with a number of bits other than 6. Alternatively, there is separate signaling indicating whether a BSS color collision has occurred for the BSS color included in the HE-SIG-A field and signaling indicating whether a BSS color collision has occurred for the BSS color included in the U-SIG field.

[0293] FIG. 20 is a diagram illustrating an example of a method for obtaining duration information according to an embodiment of the present invention.

[0294] As described in Figure 19, a STA receives multiple PPDUs or multiple signaling fields. For example, a STA receives PPDU1 and PPDU2. PPDU1 includes TXOP information in the preamble and duration information in the MAC header. PPDU2 includes TXOP information in the preamble and duration information in the MAC header.

[0295] According to one embodiment of the present invention, when a STA receives TXOP information included in the preamble of PPDU1, but fails to receive duration information included in the frame included in PPDU1, if the STA receives duration information from PPDU2 transmitted together with PPDU1, the STA does not update (set) its NAV based on the TXOP information. In this case, PPDU1 and PPDU2 constitute an A-PPDU. Alternatively, when a STA receives TXOP information included in the preamble of PPDU1, but fails to receive duration information included in the frame included in PPDU1, the STA updates (sets) its NAV based on the TXOP information.

[0296] According to one embodiment of the present invention, there is a case where a STA receives TXOP information 1 included in the preamble of PPDU1 and TXOP information 2 included in the preamble of PPDU2. According to one embodiment, in this case, the STA updates its NAV based on the TXOP information with the larger number of bits in the corresponding field of TXOP information 1 or TXOP information 2. According to one embodiment, in this case, the STA updates its NAV based on the larger value of TXOP information 1 or TXOP information 2. According to one embodiment, in this case, if PPDU1 is a HE PPDU and PPDU2 is not a HE PPDU, the STA updates its NAV based on the value included in the U-SIG field of TXOP information 1 or TXOP information 2. According to one embodiment, in this case, the STA updates its NAV based on the value included in the PPDU corresponding to the STA's standard of TXOP information 1 or TXOP information 2.

[0297] Referring to FIG. 20, a STA receives multiple PPDUs. One of the received PPDUs is a PPDU (PPDU1) including a U-SIG field, and the other is an HE PPDU (PPDU2). The multiple PPDUs constitute an A-PPDU. The U-SIG field includes an N_T-bit TXOP field, and the HE-SIG-A field included in the HE PPDU includes a 6-bit TXOP field. The STA successfully receives the U-SIG field and the HE-SIG-A. The STA may have successfully received an MPDU or frame included in PPDU1. The STA may have failed to successfully receive an MPDU or frame included in PPDU2. In this case, even if the STA receives TXOP information from PPDU2 but fails to receive duration information included in the frame, it does not update its NAV based on the TXOP information from PPDU2. This is because it received the duration information included in the frame from PPDU1, which was transmitted along with PPDU2. Alternatively, this is because TXOP information indicated by more bits was received from PPDU1 transmitted together with PPDU2.

[0298] FIG. 21 is a timing diagram illustrating a transmission scheme using multiple links.

[0299] Referring to FIG. 21, after the negotiation for the multi-link operation is completed, the AP MLD and the STA MLD perform a frame transmission / reception operation using the multi-links through an independent transmission method for each link or a simultaneous transmission method.

[0300] Specifically, when multiple links are operated in the independent transmission mode per link, as shown in Figure 10(a), each AP or terminal belonging to an AP MLD or STA MLD independently performs a channel contention process for transmitting frames on each link, and transmits frames on each link. In this case, the transmission start and end times of frames transmitted on each link are not the same. In the independent transmission mode, a transmission opportunity (TXOP) acquired through the channel contention process on each link is obtained independently from each link.

[0301] In the independent transmission method, since each link is independently accessed according to the channel occupancy state, each link can be accessed more efficiently. In this case, if the interval between the operating bands of each AP operated by AP MLD is not wide enough to allow STR operation in AP MLD or STA MLD, the independent transmission method cannot perform multiple link operation.

[0302] On the other hand, if the AP MLD or STA MLD cannot perform STR operation on the multiple links (for example, if the bandwidth interval between the links is insufficient for multiple link operation), the multiple link operation is performed in the form of simultaneous transmission operation as shown in Figure 21(b). The simultaneous transmission operation is performed by synchronizing the transmission start time or transmission end time of frames transmitted from each link.

[0303] In this case, the transmission start time or transmission end time of a frame is referred to as the transmission start time or transmission end time of the PPDU containing the frame. That is, if the lengths of frames transmitted by an AP or a terminal to each link are different, padding or padding bits are added to align the corresponding transmission end points before transmission. Alternatively, the TXOP time for frame transmission on each link is aligned. In this case, the simultaneous transmission type multi-link operation includes a step of negotiating for simultaneous transmission on multiple links and a step of performing simultaneous transmission using multiple links. The step of negotiating for simultaneous transmission includes a step of simultaneously sending a request frame to one or more links to acquire a TXOP for simultaneous transmission in an MLD (e.g., AP MLD or STA MLD) where data to be transmitted is located, and a step of transmitting a response frame after SIFS (Short Interframe Space) from the point at which reception of the request frame is completed in the MLD receiving the data.

[0304] In this case, the response frame is simultaneously transmitted over one or more links that received the request frame. The request frame is a control frame. For example, the request frame is an RTS or MU (Multi-user)-RTS frame, and the response frame is a CTS frame. Meanwhile, if a channel of a link is occupied during channel contention for simultaneous transmission, a channel access procedure for simultaneous transmission is performed, or a frame transmission operation is performed using only links with available channels.

[0305] In other words, if the AP MLD and non-AP MLD, which are a collection of multiple logical entities, cannot operate on their respective links (for example, if they transmit or receive information indicating that they do not support STR via capability information), the AP MLD and non-AP MLD form a primary link (e.g., a primary link) for transmitting and receiving beacon frames, probe request frames, and probe response frames for channel access, and multiple extended links (e.g., non-primary links) for transmitting and receiving other data.

[0306] In this case, some or all of the multiple extended links are STR operable, and the AP MLD is an NSTR soft MLD.

[0307] That is, the NSTR soft AP MLD designates one NSTR link pair as a primary link for transmitting and receiving beacon frames and probe response frames, and designates the other link of the NSTR link pair as a secondary link.

[0308] If a non-AP MLD transmits a frame (eg, a probe request frame) via an extension link other than the primary link, the NSTR soft AP MLD does not respond to the transmitted frame.

[0309] In addition to the probe response frame, an association request frame for requesting association or access and / or an association response frame are also transmitted and received only via the primary link (basic link).

[0310] Therefore, AP MLD (e.g., NSTR soft AP MLD, etc.) transmits an association response frame via the primary link only in response to an association request frame received via the primary link, and does not transmit an association response frame in response to an association request frame if an association request frame is received via a non-primary link (extension link). A channel access process for simultaneous transmission can be performed in various ways. For example, a backoff process is performed on multiple links that will perform simultaneous transmission, and carrier sensing is performed on all links until the backoff values ​​on all links reach 0. If the channels on all links are available as a result of carrier sensing, simultaneous transmission is performed using the multiple links. Alternatively, after performing a backoff operation on a link, if the channels on other links are available for a specific time (e.g., AIFS, DIFS, or PIFS) before the end of the backoff, simultaneous transmission is performed using the link with the available channel.

[0311] On the other hand, if the transmitting MLD is unable to perform STR operation on the corresponding link, and the channel state of one or some of the links is occupied (busy) while performing the channel access process for frame transmission in Figure 10(b), one of the following methods is used.

[0312] 1) After the corresponding occupancy period ends, carrier sensing is performed on the channels of both links for a specific time (e.g., PIFS, AIFS, or AIFS + backoff time) and after it is confirmed that the channels of both links are vacant, simultaneous transmission is performed using the method of FIG. 10(b).

[0313] 2) Transmission operations are performed only on links with available channels.

[0314] When the operation 2) above is performed, even after the occupancy time of the link whose channel state was occupied has ended, a backoff operation for transmitting frames is not performed until the transmission on the transmitting link ends.

[0315] On the other hand, if the transmitting MLD is capable of STR operation on the corresponding link and the receiving MLD is not capable of STR operation on the corresponding link, and if the channel state of one or some of the links is occupied (busy) during the channel access process for frame transmission in Figure 10(b), one of the following methods is used.

[0316] 1) After the corresponding occupancy period ends, carrier sensing is performed on the channels of both links for a specific time (e.g., PIFS, AIFS, or AIFS + backoff time) and after it is confirmed that the channels of both links are vacant, simultaneous transmission is performed using the method of FIG. 10(b).

[0317] 2) Transmission operations are performed only on links with available channels.

[0318] In the case of the operation 2), after the occupancy time of the link in which the channel state was occupied has ended, the channel access process is independently performed on the corresponding link to transmit the frame.

[0319] In this case, the sending MLD is AP MLD, and the AP MLD is unable to perform STR operation for some or all of the configured links. In this case, the AP MLD that is unable to perform STR operation for some or all of the links is Soft AP MLD. The Soft AP MLD is defined as an MLD that operates as a STA MLD and operates as an AP MLD only under certain conditions.

[0320] As described in FIG. 9, each AP belonging to the AP MLD operates one link and communicates with STAs through each link. Among the links operated by the AP MLD, a link capable of STR with any other link in the AP MLD is called an STR-capable link. If, among the links operated by the AP MLD, there is any other link in the AP MLD that is not capable of STR, that link is called an STR-incapable link. A group of links that are not capable of mutual STR is called an STR-incapable link group. For example, AP1, AP2, and AP3 belong to the AP MLD, and each AP operates Link1, Link2, and Link3. In this case, Link3 is capable of STR with Link1 and Link2 in the AP MLD. Reciprocal STR is not possible between Link1 and Link2 in the corresponding AP MLD. In this case, Link3 in the AP MLD is called an STR-capable link. Link1 and Link2 in the AP MLD are called STR-incapable links. In this case, a group of Link1 and Link2 that are not capable of STR with each other is called an STR-incapable link group. As another example, AP1, AP2, and AP3 belong to an AP MLD, and each AP operates link 1, link 2, and link 3. In this case, link 1 is capable of STR operation with link 3 in the AP MLD. Link 1 is not capable of STR operation with link 2. Link 2 is not capable of STR operation with link 3. In this case, link 1, link 2, and link 3 in the AP MLD are called STR-incapable links. The entire group of link 1, link 2, and link 3, which are not capable of STR operation with each other, is called a single STR-incapable link group. In other words, only when STR operation is possible between any links included in the STR-incapable group, is it called a separate STR-incapable group.

[0321] If the AP MLD is unable to perform STR on some or all links, the following frame transmission problems may occur.

[0322] FIG. 22 illustrates an example of a frame transmission / reception process according to an unpredictable uplink frame transmission operation when AP MLD is unable to perform STR.

[0323] Referring to Figure 22, the AP MLD includes AP1 and AP2. In this case, AP1 and AP2 operate link 1 and link 2, respectively. Link 1 and link 2 are not capable of STR operation. That is, link 1 and link 2 are an STR-disabled link group. In addition, AP1 and AP2 are accessed by STAs (e.g., IEEE 802.11a / b / n / ac / ax STAs) that do not belong to the STA MLD. For example, STA1 is accessed by AP1, and STA2 is accessed by AP2. The AP MLD is additionally accessed by a STA MLD.

[0324] If the AP MLD is unable to perform STR, a frame transmission error may occur due to unpredictable uplink transmission. Referring to FIG. 11(a), AP1, which belongs to the AP MLD, transmits a downlink frame to STA1. At this time, to protect the frame transmission sequence, an RTS frame and a CTS frame are additionally exchanged before transmitting the frame. While AP1 is transmitting the downlink frame, STA2, which has been accessing Link 2, completes a channel contention process for transmitting an uplink frame. After completing the channel contention process, STA2 transmits an uplink frame to AP2. At this time, because the AP MLD is unable to perform STR on Link 1 and Link 2, a frame reception error may occur in the frame received from STA2 due to the influence of intra-device interference. In other words, AP2 may not receive the frame while AP1 is transmitting the downlink frame. Due to the STR-incapable characteristic, while a downlink frame is being transmitted from one link in the STR-incapable link group, the frame transmission and reception process on other links is not smooth.

[0325] Meanwhile, frame transmission errors due to unpredictable uplink transmissions can also occur during uplink operations. Referring to FIG. 11(b), STA1 accessing link 1 transmits an uplink frame to AP1, which belongs to the AP MLD. At this time, to protect the frame transmission sequence, an RTS frame and a CTS frame are additionally exchanged before transmitting the frame. While STA1 is transmitting the uplink frame, STA2 accessing link 2 completes a channel contention process for transmitting an uplink frame. After completing the channel contention process, STA2 transmits an uplink frame to AP2. At this time, the uplink frame transmitted by STA2 is a frame requesting the AP to immediately transmit an ACK frame or a BlockAck frame. The uplink frame transmitted by STA2 ends transmission earlier than the uplink frame transmitted by STA1. Upon receiving the uplink frame from STA2, AP2 checks the received frame and transmits an Ack frame or a BlockAck frame in response. In this case, because the AP MLD is unable to perform STR on Link 1 and Link 2, a frame reception error may occur in the frame received from STA1 due to the influence of intra-device interference. Alternatively, because AP1 in the AP MLD receives a frame from STA1 on Link 1, the AP MLD recognizes that a frame reception error will occur when transmitting a frame on Link 2. Therefore, AP2 does not transmit a response frame on Link 1 or Link 2, where STR is not possible. Meanwhile, STA2, which fails to receive a response frame from AP2, recognizes that frame transmission has failed. As a result, STA2 additionally performs an operation to retransmit the frame despite successfully transmitting the frame. As a result, due to the inability of STR, while an uplink frame is being transmitted from one link, the frame transmission and reception process on other links is not smooth.

[0326] In the present invention, in an AP MLD where STR operation is not possible on some or all links, a basic link is designated and access and channel access operations are permitted only on the corresponding link. In this case, the basic link is set up in the AP MLD and access to the STA or STA MLD is performed as follows.

[0327] FIG. 23 is a conceptual diagram showing an example of an access state between the AP MLD and the STA or STA MLD by utilizing the concept of the basic link when the AP MLD is not capable of STR.

[0328] Referring to FIG. 23, the AP MLD transmits and receives specific frames only through a basic link (e.g., a primary link) among the links formed with the non-AP MLD, and performs STR operations through an extension link (e.g., a non-primary link).

[0329] Specifically, STR-capable links in an AP MLD are set as primary links. Furthermore, for STR-incapable links in an AP MLD, one link in the corresponding link group is set as the primary link. In other words, only one link from the STR-incapable link group is set as the primary link. Links that are not primary links in the corresponding STR-incapable link group are set as extended links. Meanwhile, multiple primary links are set in one AP MLD. For example, an AP MLD includes AP1, AP2, and AP3, and each AP operates Link1, Link2, and Link3. In this case, Link3 is an STR-capable link, and Link1 and Link2 are in the STR-incapable link group. In this case, one of Link1 and Link2 in the AP MLD is set as the primary link, and Link3 is also set as the primary link. For example, the AP MLD sets Link1 and Link3 as primary links. Alternatively, the AP MLD sets Link2 and Link3 as primary links.

[0330] In this case, the legacy STA transmits and receives frames only to the AP with which the basic link is established among the multiple APs that make up the NSTR AP MLD.

[0331] In other words, an AP that is not capable of STR operation sets a basic link. STAs that do not belong to the STA MLD can only access the basic link. STAs that do not belong to the STA MLD cannot access the extended link. For example, if the AP MLD sets link 1 and link 3 as the basic, STA3 that does not belong to the STA MLD can access AP1 or AP3. In other words, STA3 cannot access AP2.

[0332] Meanwhile, to simplify the operation of the AP MLD and prevent excessive channel load on the basic link, the number of STR-incapable links operated by the AP MLD is limited. That is, only when the number of STR-incapable links in the MLD is below a certain number, the AP MLD is allowed to operate as an AP MLD. For example, only when the number of STR-incapable links in the corresponding MLD is two or less, the AP MLD is allowed to operate as an AP MLD. In this case, if Link 1, Link 2, and Link 3 are configured in the MLD, the corresponding MLD is restricted to operate as an AP MLD only when at least one link is a STR-capable link.

[0333] Specifically, the NSTR soft AP MLD uses only one of the multiple entities (APs) constituting the NSTR soft AP MLD to form a primary link (main link) with one of the multiple entities (STAs) constituting the non-AP MLD. The AP and STA forming the main link transmit and receive beacon frames and probe response frames via the main link. The NSTR soft AP MLD can form a main link in which STR operation is not possible with the non-AP MLD only if the number of links in which STR operation is not possible among the links of the NSTR soft AP MLD is less than a specific number. For example, the NSTR soft AP MLD sets a parameter indicating the maximum number of links in which STR operation is possible in a specific field of the control frame to a value one less than the number of links in which STR operation is possible, and sets the value of a field indicating whether a link in which NSTR operation is possible exists to a specific value (e.g., "1"). If the value of the field indicating whether a link in which NSTR operation is possible exists indicates that a link in which NSTR operation is possible exists, the value of the link ID indicating the number of links is set within a specific range.

[0334] Meanwhile, the STA MLD performs an access process for the AP MLD. At this time, when the multi-link negotiation process described in FIG. 9 is performed including an STR-incapable link in the AP MLD, the multi-link negotiation process is performed only if the basic link in the corresponding STR-incapable link group is included. For example, if the AP MLD is unable to perform STR operation on Link 1 and Link 2 and sets Link 1 and Link 3 as the basic links, the STA MLD performs a process for multi-link operation to use Link 1 and Link 2. Alternatively, the STA MLD performs a negotiation process for multi-link operation to use Link 1 and Link 3. However, the STA MLD cannot perform a negotiation process for multi-link operation to use Link 2 and Link 3.

[0335] A STA that does not belong to the STA MLD performs an access process with the AP MLD, which does not allow the STA to operate. In this case, the AP MLD rejects the access request from the STA on a link other than the basic link as follows:

[0336] 24 is a conceptual diagram showing an example of an access process between an AP MLD and a STA not belonging to the MLD when the AP MLD is unable to perform STR. In FIG. 24, the same channel access process as in FIG. 5 will not be described.

[0337] Referring to Figure 24, the AP MLD includes APs, which are multiple logical entities, and each AP operates a link. In this case, some or all of the links operated by the AP MLD are not capable of STR operation. The AP MLD configures one or more basic links. For example, the AP MLD configures link 1 and link 3 as basic links. In this case, AP1 in the AP MLD operates on link 1, and AP3 operates on link 3. In this case, STAs not belonging to the STA MLD perform the scanning and access process with AP1 or AP3 as described in Figure 5.

[0338] If the STA attempts to perform an access process via link 2, which is not the primary link, AP2 rejects the request. Therefore, if the STA transmits a probe response frame via link 2, AP2 does not transmit a response to the probe response frame. In other words, it does not transmit a probe response frame. In other words, the AP transmits beacon frames and probe response frames only via the primary link.

[0339] Meanwhile, AP2 transmits periodic beacon frames for terminal operation on the corresponding link. The beacon frames are transmitted at the same time as beacon frames transmitted on basic links in the STR-disabled link group within the corresponding AP MLD. That is, the beacon frames transmitted by AP2 are transmitted at the same time as beacon frames transmitted by AP1. STA2 receives the beacon frames and can perform passive scanning based on the contents of the received beacon frames. Alternatively, the beacon frames are set to be unreadable by terminals that are not in the STA MLD. For example, the IBSS STA subfield and ESS subfield values ​​in the Capability information field within the beacon frame are both set to 1, so that STAs that are not in the STA MLD cannot recognize the BSS type of the corresponding AP. STAs that cannot read the beacon frames and perform scanning operations determine that there is no valid AP on the corresponding channel and do not perform the access process. As another example, the beacon frame includes a BSS load information element. The BSS load information element includes an Element ID field, a length field, an associated STA number field, a channel utilization rate field, and an admission control capacity field. In this case, to control the scanning operation via the beacon frame, the associated STA number field in the BSS load information element is set to the maximum. Alternatively, the channel utilization rate field is set to the maximum. The STA receiving the beacon frame determines that the BSS load of the corresponding AP (e.g., AP2) is the maximum, and does not perform an access process with the corresponding AP.

[0340] As another example, beacon frames are not transmitted in the extended link. For example, AP2 does not transmit beacon frames. STAs that do not receive the beacon frames and cannot perform scanning operations determine that there is no valid AP on the corresponding channel and do not perform the access process.

[0341] On the other hand, if the STA can read the beacon frame, the STA transmits an access request frame to AP2 based on the result of passive scanning. AP2, which receives the access request, transmits an access response frame in response to the access request frame. The access response frame includes an indicator to reject the access request. If AP2 rejects the access request in response to the access request frame, the access response frame further includes a field indicating a status code proposing access to another link. For example, the status code field is set to a value of 82 to propose BSS switching. At this time, information about the primary link to which access is proposed is additionally included and transmitted. The information about the primary link is transmitted in the form of a Neighbor Report information element. The Neighbor Report information element includes at least one of BSSID, channel, operation class, and timing information.

[0342] Upon receiving the access response frame including the rejection indicator from AP2, the STA checks the contents of the received access response frame to confirm that the access request has been rejected. At this time, the STA checks the value of the status code field in the access response frame to confirm that it proposes access to another BSS, and checks the contents of the Neighbor Report information element to confirm the BSS information. The STA checks the basic link information included in the Neighbor Report information element, moves to the channel indicated by the information, and performs the access process described in Figure 5. Alternatively, the STA transmits an access request frame to the AP of the corresponding basic link based on the contents of the corresponding Neighbor Report information element.

[0343] Meanwhile, when the STA MLD performs an access process with the AP MLD, it performs a negotiation process for multiple link operation among multiple links including the basic link in the STR-disabled link group as described in Figure 9. In this case, the negotiation process for multiple link operation is performed as follows.

[0344] 25 is a conceptual diagram showing an example of an access process between the AP MLD and the STA MLD when the AP MLD is unable to perform STR. In FIG. 25, the same processes as the channel access process of FIG. 5 and the negotiation process for performing multi-link operation of FIG. 9 are omitted.

[0345] Referring to Figure 25, the AP MLD includes multiple APs, and each AP operates a link. In this case, STR operation is not possible on some or all of the links operated by the AP MLD. For example, the AP MLD operates on link 1, link 2, and link 3. In this case, STR operation is not possible on link 1 and link 2. In other words, link 1 and link 2 are an STR-incapable link group. The AP MLD configures one or more basic links. For example, the AP MLD configures link 1 and link 3 as basic links. In this case, AP1 in the AP MLD operates on link 1, AP2 operates on link 2, and AP3 operates on link 3.

[0346] The STA MLD performs the access procedure and negotiation process for multiple link operation with the AP MLD over link 1 or link 3 as described in FIGS. 5 and 9. At this time, the STA MLD transmits a probe request frame including an indicator requesting link information for multiple link operation. The AP MLD that receives the probe request frame checks the corresponding indicator and transmits a probe response frame including link information for multiple link operation. The probe response frame including the link information additionally indicates STR-capable links, STR-incapable link groups, and basic link information. The STA MLD receives the probe response frame and receives the link information included in the corresponding frame. It also additionally checks the STR-capable links, STR-incapable link groups, and basic link information indicated in the probe response frame. After checking the probe response frame, the STA MLD transmits an access request frame to the AP MLD. At this time, the request indicator requesting multiple link operation is included. Upon receiving the access request frame from the STA MLD, the AP MLD checks the indicator requesting multi-link operation and determines whether it requests the use of a link in the STR-disabled link group or whether it requests the use of a basic link in the STR-disabled link group when using the corresponding link. For example, the STA MLD checks whether it requests the use of one or more links from Link 1 and Link 2. If the corresponding link is used, it checks whether it requests the use of Link 1, which is the basic link. If the check result shows that the STA MLD requests the use of the STR-disabled link group but does not request the use of a basic link in the STR-disabled link group including the corresponding link, the AP MLD sends an access response frame indicating a denial in response to the access request frame. For example, if the STA MLD requests the use of only Link 2 and Link 3, the AP MLD rejects the request. Alternatively, the AP MLD transmits an access response frame allowing multi-link operation, including information on other links different from the requested link group.On the other hand, if the STA MLD requests a multi-link operation including the STR-capable link and the basic link of the STR-incapable link group, the AP MLD transmits an access response frame allowing the multi-link operation as described in FIG.

[0347] Meanwhile, the STA MLD also performs the above-mentioned access procedure for link 2. That is, the STA MLD transmits a probe request frame including an indicator requesting link information for multiple link operation for link 2. At this time, the AP MLD transmits a probe response frame including link information in response to the probe request frame only if the corresponding request indicator for multiple link operation is included. The probe response frame including the link information additionally indicates STR-capable links, STR-incapable link groups, and basic links. Upon receiving the probe response frame, the STA MLD checks the link information, STR-capable links, STR-incapable link groups, and basic link information included in the probe response frame, and exchanges access request frames and access response frames, including a negotiation process for multiple link operation, with the AP MLD according to the confirmed contents.

[0348] Meanwhile, the STR-enabled links, STR-disabled link groups, and basic link information are included in the RNR element in the form of a TBTT information field, or are included in a multiple link information element that includes separate link information. When included and transmitted in the multiple link information element, the multiple link information element is configured as follows:

[0349] FIG. 26 is a block diagram showing an example of a link indication information element including an indicator indicating a basic link.

[0350] Referring to FIG. 26, the multiple link information element includes information for channel access and frame transmission and reception between the AP MLD and the non-AP MLD.

[0351] In detail, the multiple link information element includes integrated information for the MLD and individual information for each link. The integrated information for the multiple link includes information such as the address of the corresponding MLD and the number of links supported by the corresponding MLD. The multiple link information element does not include individual information for each link. Alternatively, if the multiple link information element is included in a probe response frame transmitted in response to a probe request frame including a request indicator for multiple link operation, the corresponding information element includes individual information for each link. If the multiple link information element is transmitted in an access request frame or access response frame including the negotiation process for multiple link operation described with reference to FIGS. 9 and 25, the corresponding multiple link information element includes individual information for each link.

[0352] The individual information for the link is included in the form of a sub-information element within the multiple link information element. The individual information for each link is included individually for each link, and the sub-information element includes a link ID field, an indication field indicating whether the multiple link information element includes all information for the link (e.g., all information included in the beacon frame transmitted through the link), and a field indicating whether STR operation with other links is possible. The STR operation indication field includes, in a bitmap format, whether STR is possible for other link IDs. For example, a value of 0 at bit x position in the field indicates that the corresponding link is not capable of linked STR operation with link ID x. The value of the bit position corresponding to the corresponding link ID is set to 1. Therefore, if all fields in the bitmap are set to 1, the corresponding link is indicated as an STR-capable link. On the other hand, if even one bit is set to 0, the corresponding link is indicated as an STR-incapable link, in which STR operation with the link ID corresponding to the bit position set to 0 is not possible. If the corresponding link is an STR-incapable link, the field indicating whether the STR is operational further includes information about the basic link and information about the STR-incapable link group. In this case, the information about the basic link is indicated by the link ID of the link set as the basic link among the links belonging to the corresponding STR-incapable link group. The STR-incapable link group displays the link IDs of the STR-incapable link group including the corresponding link in a bitmap format. For example, if a link with a link ID of 0 and a link with a link ID of 1 constitute an STR-incapable link group, the values ​​of the bit 0 position and bit 1 position of the corresponding bitmap are set to 1.

[0353] That is, the AP MLD (including the NSTR soft AP MLD) transmits link information regarding at least one link established between the AP MLD and the non-AP MLD to the non-AP MLD, where the link information includes at least one of the number of the links established between the non-AP MLD and the AP MLD, a bitmap indicating whether each of the links supports the STR operation, and the above-mentioned information.

[0354] On the other hand, if the AP MLD is unable to perform the STR operation on some links, it sets up a basic link and performs frame transmission with the STA and STA MLD as follows.

[0355] FIG. 27 is a diagram showing an example of a frame transmission procedure between the AP MLD and the STA MLD using the concept of a basic link when the AP MLD is not capable of STR.

[0356] Referring to Figure 27, if an AP MLD establishes a basic link for one or more links, the AP MLD is only allowed to perform an independent channel access operation on the established basic link. In other words, frame transmission cannot be performed through a channel access operation on an extended link. Furthermore, an STA or STA MLD associated with the AP MLD is only allowed to perform an independent channel access operation on the basic link established by the AP MLD. In this case, the AP MLD and the STA MLD perform a multi-link operation using a simultaneous transmission method as shown in Figure 10(b) by using both extended links in the STR-disabled link group. In this case, the multi-link operation is used only when a basic link in the STR-disabled link group can be used. In other words, if the corresponding basic link is in a channel busy state, frame transmission using only the remaining links in the STR-disabled link group is not allowed.

[0357] That is, as described above, the NSTR soft AP MLD that does not support STR operation forms multiple links with non-AP STAs, and if the number of links that do not support STR operation among the multiple formed links is less than a specific number, one of the at least one link that does not support STR operation is set as a basic link (or primary link), and the remaining links of the at least one link excluding the basic link are set as extended links (or non-primary links).

[0358] The NSTR soft AP MLD transmits beacon frames and probe response frames for channel access only via the basic link, but if a non-AP STA transmits a probe request frame for channel access via the extended link, the NSTR soft AP MLD does not transmit a response to the transmitted probe request frame.

[0359] At this time, the NSTR soft MLD transmits link information regarding the link established between the non-AP MLDs to the non-AP MLDs via control information, etc., as described above.

[0360] For example, AP MLD operates on Link 1, Link 2, and Link 3. In this case, STR operation is not possible on Link 1 and Link 2. In other words, Link 1 and Link 2 are an STR-inhibited link group. The AP MLD configures one or more basic links. For example, AP MLD configures Link 1 and Link 3 as basic links. In this case, AP 1 in the AP MLD operates on Link 1, AP 2 operates on Link 2, and AP 3 operates on Link 3. In this case, STAs that do not belong to the STA MLD cannot access Link 2. In AP MLD and STA MLD, a channel access process is performed on Link 2, and frames cannot be transmitted using only that link. In addition, AP MLD and STA MLD use Link 2 as if it were Link 1, and only use it in multiple link operation using the simultaneous transmission method. In other words, if Link 1 is in a channel busy state, frame transmission using only Link 2, excluding Link 1, is not permitted.

[0361] Generally, transmission using only the extension link in the STA-incapable link group is not permitted. Meanwhile, if the frame transmitted by the STA MLD does not require an immediate response frame, an independent channel access is performed on the extension link as an exception. Also, to further improve the efficiency of the frame transmission operation, the STA MLD starts a frame exchange sequence on the extension link, thereby inducing a simultaneous transmission type multi-link operation. The independent channel access operation on the extension of the exceptional STR-incapable link group is performed as follows.

[0362] FIG. 28 shows a first embodiment of the present invention, in which channel access and frame transmission are performed exceptionally in an extended link when AP MLD is unable to perform STR.

[0363] Referring to FIG. 28, when a STA MLD is transmitting an uplink frame on a basic link of an STR-incapable link group, the STA MLD performs a channel contention procedure to transmit a frame that does not request a response on another link in the STR-incapable link group. The STA MLD is capable of STR operation within the corresponding STR-incapable link group. At this time, the STA MLD compares the end time of the transmission of a PPDU containing a frame to be transmitted at the time the channel contention procedure is completed on the other link with the end time of the transmission of a PPDU containing a frame being transmitted on the basic link. If it is determined that the transmission of a PPDU to be transmitted on another link will end before the end time of the transmission of a PPDU containing a frame being transmitted on the basic link, the STA MLD transmits a frame that does not request a response on an extension link in the corresponding STR-incapable link group. On the other hand, if it is determined that the end time of the transmission of a PPDU containing a frame to be transmitted at the time the corresponding channel access operation is completed is after the end time of the transmission of a PPDU containing a frame being transmitted on the basic link, frame transmission on the extension link is not performed.

[0364] For example, the AP MLD operates Link 1 and Link 2, but Link 1 and Link 2 are not capable of STR operation. In this case, Link 1 of the AP MLD is set as the primary link. AP 1 of the AP MLD operates on Link 1, and AP 2 operates on Link 2. The STA MLD associated with the AP MLD performs a multi-link operation using Link 1 and Link 2. In this case, if Link 2 is in a busy state during channel access for the multi-link operation, a channel access procedure is performed using only Link 1 to transmit a frame. Alternatively, if there is no frame to transmit on Link 2, a channel access procedure is performed on Link 1 to transmit a frame. While the STA MLD is transmitting a frame on Link 1, if the channel state of Link 2 changes to idle or data to be transmitted on Link 2 occurs while the channel is free, and the frame to be transmitted on Link 2 does not require a response frame, a channel access procedure on the corresponding link is performed. Alternatively, the channel state is checked from the time of generation of the transmission frame until a specific time (e.g., a time corresponding to AIFS + backoff value) before. When the STA MLD completes the channel access for link 2 or completes checking the channel status, it compares the transmission end point of the PPDU containing the frame to be transmitted over link 2 with the transmission end point of the PPDU containing the frame being transmitted over link 1. If it determines that the transmission end point of the PPDU containing the frame to be transmitted over link 2 is before the transmission end point of the PPDU containing the frame being transmitted over link 1, the STA MLD transmits the corresponding frame over link 2.

[0365] Meanwhile, in the operation of Figure 28, if the frame transmitted on the basic link of the STR-disabled link group is not a frame transmitted by the AP MLD, a channel contention process is performed to transmit the frame even if it is not an uplink frame transmitted by the corresponding STA MLD. That is, when the end point of transmission of the uplink frame on the basic link is recognized as follows, the frame is transmitted on another link as follows.

[0366] FIG. 29 shows a second embodiment showing yet another example of the operation in which channel access and frame transmission operations are performed exceptionally in an extended link when AP MLD is unable to perform STR.

[0367] 29, when the STA MLD recognizes that another UE is transmitting an uplink frame on a primary link of an STR-disabled link group, the STA MLD performs a channel contention process to transmit a frame that does not request a response within the corresponding transmission time on another link in the corresponding STR-disabled link group. For example, if Link 1 and Link 2 are in an STR-disabled link group and Link 1 is the primary link, the STA MLD recognizes a frame transmitted by another UE (e.g., STA 3) on Link 1 and checks the transmission end time and transmitting UE address of the PPDU containing the corresponding frame. At this time, the transmission end time of the PPDU containing the corresponding frame is recognized by checking the L-SIG field in the preamble. If the transmission address of the frame transmitted on Link 1 is not the address of the AP MLD, the STA MLD performs a channel contention process to transmit a frame that does not request a response on Link 2 during the transmission time of the PPDU containing the corresponding frame. At this time, the STA MLD compares the transmission end time of the PPDU containing the frame to be transmitted at the time the channel contention process on the other link is completed with the transmission end time of the PPDU containing the frame being transmitted on the primary link. In this case, if it is determined that the transmission of a PPDU transmitted over another link will end before the end of the transmission of a PPDU containing a frame currently being transmitted over a link, the STA MLD transmits a frame that does not request a response over an extended link within the corresponding STR-incapable link group. For example, if the STA MLD recognizes a PPDU containing a frame transmitted by another terminal over link 1, it performs a channel access process to transmit a frame that does not request a response over link 2. If it determines that the end of the transmission of the PPDU containing the frame is before the end of the transmission of the PPDU recognized over link 1 at the time the corresponding channel access operation is completed, it transmits the frame over link 2. Meanwhile, if the transmission address of the frame transmitted over the basic link matches the address of the AP MLD, it is not possible to perform a channel access process to transmit a frame over an extended link during the transmission time of the PPDU containing the frame. Furthermore, if it is not possible to determine the end of the transmission of the PPDU transmitted by another terminal over the basic link, it is not possible to perform a channel access process over another link within the same STR-incapable link group.Alternatively, if it is determined that the end of transmission of the PPDU containing the frame to be transmitted at the time of completion of the channel access operation is after the end of transmission of the PPDU containing the frame being transmitted on the basic link, the frame transmission on the extension link is not performed.

[0368] On the other hand, in the operation of Figure 28 described above, if the frame to be transmitted on the extended link of the STR-disabled link group is a frame that requests a response frame (e.g., an ACK frame or a BlockAck frame) from the AP MLD, and the end point of transmission of the PPDU containing the frame is before the end point of transmission of the PPDU containing the previously transmitted frame, the multiple link operation is performed as follows.

[0369] FIG. 30 shows a third embodiment showing yet another example of the operation in which channel access and frame transmission operations are performed exceptionally in an extended link when AP MLD is unable to perform STR.

[0370] 30, when a STA MLD is transmitting an uplink frame through a basic link of an STR-disabled link group, the STA MLD performs a channel contention process to transmit a frame requesting a response through another link in the corresponding STR-disabled link group. The STA MLD is capable of STR operation within the corresponding STR-disabled link group. For example, if Link 1 and Link 2 are in an STR-disabled link group and Link 1 is the basic link, the STA MLD performs a channel contention process to transmit a frame requesting a response through Link 2 during the transmission time of the frame being transmitted through Link 1. At this time, the STA MLD compares the end time of the transmission of a PPDU containing a frame to be transmitted when the channel contention process is completed through the other link with the end time of the transmission of a PPDU containing a frame being transmitted through the basic link. At this time, if it is determined that the transmission of the PPDU to be transmitted through the other link will end before the end time of the transmission of the PPDU containing the frame being transmitted through the link, the STA MLD transmits a frame requesting a response through an extension link in the corresponding STR-disabled link group. At this time, padding bits are added to the frame and PPDU transmitted on the extended link to align the frame transmission end points on the two links. For example, if the STA MLD is transmitting a PPDU containing a frame on link 1, it performs a channel access process to transmit a frame requesting a response on link 2. If it is determined that the transmission end point of the PPDU containing the frame is before the transmission end point of the PPDU transmitted on link 1 when the channel access operation is completed, the frame is transmitted on link 2. At this time, padding bits are added to align the transmission end points of the PPDU transmitted on link 1 and link 2. At this time, if the difference between the transmission end point of the PPDU on link 1 and the transmission end point on link 2 is within a specific time (e.g., 4 μs), it is determined that the transmission end points on the two links are the same.

[0371] The AP MLD receives the frame transmitted by the STA MLD and transmits a response frame (e.g., an ACK frame or a BlockAck frame) in response to the frame. At this time, the transmission length of the PPDU including the frames transmitted over the multiple links is set to the same. If the STA MLD has additional frames to transmit after receiving the response frame, it performs a frame exchange operation using a simultaneous transmission multiple link operation as shown in Figure 10(b).

[0372] On the other hand, when the AP MLD performs a frame exchange sequence for transmitting a downlink frame on a basic link in an STR-disabled link group, the STA MLD receiving the corresponding downlink frame performs channel access on another link in the corresponding link group. After performing the corresponding channel access process, the STA MLD transmits an indicator to the AP MLD informing it that another link is available, thereby inducing a simultaneous transmission multiple link operation. In this case, the frame transmission process is performed exceptionally as follows.

[0373] FIG. 31 shows a fourth embodiment showing yet another example of the operation in which channel access and frame transmission operations are performed exceptionally in an extended link when AP MLD is unable to perform STR.

[0374] Referring to FIG. 31, the AP MLD is unable to perform STR operation for some or all links. In this case, the AP MLD performs a channel access process for performing a simultaneous transmission type multi-link operation using an STR-disabled link group. That is, the channel access for transmitting frames is performed in the manner shown in FIG. 21(b). At this time, the channel is occupied for the extension link. In this case, as described in FIG. 21, frame transmission is performed using only a basic link with an available channel or some links including the basic link. For example, if link 1 and link 2 of the AP MLD are in an STR-disabled link group and link 1 is the basic link, if the channel for link 2 is occupied during channel access for performing a multi-link operation, frame transmission is performed using only link 1. At this time, the AP MLD performs an RTS frame and CTS frame exchange procedure before transmitting the frame to protect the frame to be transmitted. At this time, the RTS frame is transmitted in the form of an MU (Multi-user)-RTS frame.

[0375] When the AP MLD performs channel access for a multi-link operation but transmits using only some links due to channel conditions, the AP MLD includes an indicator indicating this. In this case, the indicator is a link usage request indicator that causes the STA MLD receiving the corresponding frame to transmit a simultaneous transmission request frame when an occupied link changes to an idle state. The link usage request indicator is transmitted in the MU-RTS frame. For example, if the UL Length field in the MU-RTS is set to a non-zero value, the link ID of the extended link for which simultaneous transmission is to be performed is indicated in a bitmap format. Alternatively, the UL Length field in the MU-RTS indicates the link ID of the extended link for which the STA MLD transmits the simultaneous transmission request frame. Alternatively, the link usage request indicator is transmitted in the HT Control field of a frame transmitted by the AP MLD. In this case, the first two bits of the HT Control field are set to 1 to indicate that the HT Control field is configured as an A-control field. The A-control field section is composed of one or more subfields containing transmission information. In this case, the subfield includes a subfield indicating extended link information for which simultaneous transmission is to be performed. The subfield indicating the used link information is composed of a control ID and multiple link information. The control ID is set to a value (e.g., 7) that is not used in other information subfields, indicating that the corresponding subfield is a subfield indicating extended link information for which simultaneous transmission is to be performed. Multiple link information includes a link ID. Alternatively, the subfield does not include link information. If the subfield does not include link information, it refers to all extended links not used for frame transmission among the STR-disabled link group used by AP MLD.

[0376] The AP MLD transmits frames to be transmitted through a basic link or some links including the basic link, and the STA MLD receives the corresponding frames. At this time, if the corresponding STA MLD checks a link use request indicator in the MU-RTS frame received from the AP MLD, it checks the channel status of the indicated extended link in the STR-unavailable link group. Alternatively, if the STA MLD checks a link use request indicator in a data frame received from the AP MLD, it checks the channel status of the indicated extended link in the STR-unavailable link group. Alternatively, if the STA MLD receives a link use request indicator from the AP MLD but cannot check information about the requested link, it checks the channel status of all extended links included in the corresponding STR-unavailable link group. Alternatively, when the AP MLD and STA MLD perform a negotiation process to use multiple links for the corresponding STR-unavailable link group, the STA MLD checks the channel status of any other extended link while receiving a frame from the AP MLD through some links in the STR-unavailable link group. As a result of checking the channel status of the extended links in the STR-incapable link group, if the channel is available for other links in the link group from the start of transmission of a response frame (e.g., an ACK frame or BlockAck frame) for frame transmission to the basic link and some of the links until a specific time before (e.g., from the start of transmission of the response frame until the time before the 'AIFS+backoff time') the STA MLD transmits the frame using both links. In this case, the response frame is transmitted to the basic link and some of the links including the basic link, and a request frame requesting simultaneous transmission is transmitted to the remaining links. The request frame is the same as or similar to a trigger frame, PS-Poll frame, or U-APSD trigger frame. If the request frame is a trigger frame, the trigger frame is an MU-RTS frame. Alternatively, the uplink transmission length field of the basic type trigger frame is set to 0. In this case, padding bits are added to transmit the trigger frame to align the end of PPDU transmission with the response frame transmitted on the other links.

[0377] Upon receiving the request frame requesting simultaneous transmission, the AP MLD confirms that the corresponding STA MLD requests simultaneous transmission using the remaining links in the corresponding STR-disabled link group, and performs the following frame transmission sequence by additionally utilizing the corresponding link. That is, the AP MLD transmits a downlink frame as shown in FIG. 21(b) by additionally utilizing the link on which the request frame was transmitted. At this time, if the transmission end points of the PPDU including the downlink frame do not match, padding bits are added and transmitted. Meanwhile, the AP MLD receives the request frame and senses the channel state before transmitting the downlink frame. That is, the AP MLD performs a carrier sensing operation from the end of reception of the request frame to the start of transmission of the downlink frame. The carrier sensing operation includes one or more of energy sensing, virtual sensing via the preamble value of the received frame, and NAV (Network Allocation Vector) confirmation.

[0378] Meanwhile, if the AP MLD that received the request frame for simultaneous transmission does not have data to transmit in the corresponding STA MLD for simultaneous transmission, it transmits the frame to another STA MLD that has negotiated to use the corresponding link. In this case, simultaneous transmission is performed using multiple links, and the STA MLD that receives data on each link is a different device. The operation of transmitting data to another STA MLD on each link is performed as follows.

[0379] FIG. 32 shows a fifth embodiment showing yet another example of the operation in which channel access and frame transmission operations are performed exceptionally in an extended link when AP MLD is unable to perform STR.

[0380] Referring to FIG. 32, the AP MLD is unable to perform STR operation for some or all links. In this case, the AP MLD performs a channel access process for performing a simultaneous transmission type multi-link operation using an STR-disabled link group. That is, the AP MLD performs channel access for transmitting frames in the manner shown in FIG. 21(b). At this time, the channel is occupied for the extension link. In this case, as described in FIG. 21, frame transmission is performed using only a basic link with an available channel or some links including the basic link. For example, if link 1 and link 2 of the AP MLD are in an STR-disabled link group and link 1 is the basic link, if the channel for link 2 is occupied during channel access for performing a multi-link operation, the AP MLD performs a frame transmission operation using only link 1. At this time, the AP MLD performs an RTS frame and CTS frame exchange procedure before transmitting the frame to protect the frame to be transmitted. At this time, the RTS frame is transmitted in the form of an MU (Multi-user)-RTS frame.

[0381] When the AP MLD transmits a frame using only some of the links in the STR-disabled link group, it transmits an RTS frame, an MU-RTS frame, or a frame including a link use request indicator, as shown in FIG. 31. The STA MLD receives the link use request indicator included in the RTS frame, MU-RTS, or data frame transmitted over some of the links in the STR-disabled link group. Depending on the content of the received link use request indicator, the STA MLD checks the channel status of the indicated extension link channel during the transmission time of the downlink frame in the STR-disabled link group. Alternatively, when the AP MLD and the STA MLD perform a negotiation process to use multiple links for the corresponding STR-disabled link group, the STA MLD optionally checks the channel status of other extension links while receiving frames from the AP MLD over some of the links in the STR-disabled link group. As a result of checking the channel status of the extended links in the STR-disabled link group, if the channel is available for other links in the link group from the start of transmission of a response frame (e.g., an ACK frame or a BlockAck frame) for frame transmission for the basic link and some links until a specific time before (e.g., from the start of transmission of the response frame until the AIFS+backoff time), the STA MLD transmits a request frame requesting simultaneous transmission on the extended links. The request frame is a frame that requests the AP MLD to use multiple links using the simultaneous transmission method. The request frame is the same as or similar to a trigger frame, PS-Poll frame, or U-APSD trigger frame. If the request frame is a trigger frame, it is an MU-RTS frame. Alternatively, the uplink transmission length field of the basic trigger frame is set to 0. In this case, padding bits are added to the request frame to align the end of PPDU transmission with the end of response frames transmitted on other links.

[0382] Upon receiving the request frame requesting simultaneous transmission, the AP MLD confirms that the corresponding STA MLD requests simultaneous transmission using the remaining links in the corresponding STR-incapable link group. If the corresponding AP MLD has no data to transmit to the STA MLD that transmitted the request frame on the link on which the request frame was transmitted, it transmits a downlink data frame to another STA MLD negotiated to use the corresponding link. That is, if the request frame was received from STA MLD1 but no frame to transmit to STA MLD1 on the corresponding link, it transmits a downlink data frame to STA MLD2. The process of transmitting frames to multiple UEs using multiple links is similar to the multiple link operation method of the simultaneous transmission method. That is, the link on which the request frame was transmitted is additionally used to transmit downlink frames as shown in FIG. 21(b). If the transmission end points of the PPDUs containing the downlink frames do not coincide, padding bits are added and transmitted. Meanwhile, the AP MLD receives the request frame and senses the channel status of the link on which the request frame was transmitted before transmitting the downlink frame. That is, the AP MLD performs carrier sensing during the time from the completion of reception of the request frame to the start of transmission of the downlink frame, which includes at least one of energy sensing, virtual sensing via the preamble value of the received frame, and NAV (Network Allocation Vector) confirmation.

[0383] Meanwhile, the process of exceptionally performing a channel access operation in an extended link by the STA MLD described in Figure 31 to induce a simultaneous transmission operation is also performed by the AP MLD. That is, when the STA MLD performs a frame exchange sequence for transmitting an uplink frame in a basic link in the STR-disabled link group, the AP MLD receiving the corresponding uplink frame performs channel access and frame transmission in another extended link in the corresponding STA-disabled link group. In this case, the transmitted frame is a frame requesting the use of multiple links using the simultaneous transmission method. This process induces an uplink multiple link operation as shown in Figure 21(b). In this case, the exceptional frame transmission process in the extended link is performed as follows.

[0384] Figure 33 shows a sixth embodiment of the present invention, which illustrates another example of an exceptional operation of channel access and frame transmission in an extended link when AP MLD is unable to perform STR. In Figure 33, operations that are the same as or similar to those described in Figure 31 will not be described.

[0385] Referring to Figure 33, AP MLD does not allow STR operation for some or all links. Links for which STR operation is not possible in AP MLD are called an STR-incapable link group. Links for which STR operation is possible in AP MLD are set as basic links. Also, one link among the links included in the STR-incapable link group in AP MLD is additionally set as a basic link. Links that are not basic links in the STR-incapable link group are called extended links.

[0386] At this time, the STA MLD, which has completed the negotiation process for the multi-link operation with the AP MLD, performs a channel access process for performing the multi-link operation in the simultaneous transmission mode using the STR-disabled link group. That is, the channel access for transmitting frames is performed in the manner shown in FIG. 31(b). At this time, the channel is occupied for the extension link. In this case, as described in FIG. 31, frame transmission is performed using only the basic link where the channel is available or some links including the basic link. For example, if Link 1 and Link 2 of the AP MLD are in the STR-disabled link group and Link 1 is the basic link, if the channel for Link 2 is occupied during the channel access for the multi-link operation by the STA MLD, the frame transmission operation is performed using only Link 1. At this time, the STA MLD exchanges the RTS frame and CTS frame before transmitting the frame to protect the frame to be transmitted. At this time, the RTS frame is transmitted in the form of an MU (Multi-user)-RTS frame.

[0387] When the STA MLD performs channel access for multiple link operation but transmits using only some links due to channel conditions, the STA MLD transmits a frame including the link use request indicator described in Figure 20. The link use request indicator is transmitted in an MU-RTS frame, or the link use request indicator is transmitted in the form of an A-control field in an HT-Control field in a frame transmitted by the STA MLD.

[0388] The AP MLD receives frames transmitted through a basic link or some links including the basic link. At this time, if the corresponding AP MLD receives a link use request indicator from the STA MLD, it checks the channel status of the indicated extended link in the STR-unavailable link group. Alternatively, if it receives a link use request indicator from the STA MLD but cannot check information about the requested link, it checks the channel status of all extended links included in the corresponding STR-unavailable link group. Alternatively, if the AP MLD and STA MLD perform a negotiation process to use multiple links for the corresponding STR-unavailable link group, the AP MLD checks the channel status of any other extended links while receiving frames from the STA MLD through some links in the STR-unavailable link group. As a result of checking the channel status of the extended links in the STR-disabled link group, if the channel is available for other links in the link group from the start of transmission of a response frame (e.g., an ACK frame or a BlockAck frame) for frame transmission for the basic link and some links until a specific time before (e.g., from the start of transmission of the response frame until the AIFS+backoff time), the AP MLD transmits a request frame to the STA MLD over the available extended link to request simultaneous transmission. The request frame is a frame that requests the STA MLD to use multiple links using the simultaneous transmission method. The request frame is the same as or similar to a trigger frame, PS-Poll frame, or U-APSD trigger frame. If the request frame is a trigger frame, it is an MU-RTS frame. Alternatively, the uplink transmission length field of the basic trigger frame is set to 0. In this case, padding bits are added to the request frame to align the end of PPDU transmission with the end of response frames transmitted over other links.

[0389] Upon receiving the request frame requesting simultaneous transmission, the STA MLD confirms that the AP MLD requests simultaneous transmission using the remaining links in the corresponding STR-disabled link group. If the AP MLD that transmitted the request frame has no data to transmit over the link through which the request frame was transmitted, the STA MLD performs the following frame transmission sequence using the additional link. That is, the uplink frame is transmitted over the additional link through which the request frame was transmitted, as shown in FIG. 31(b). If the transmission end points of the PPDU containing the uplink frame do not match, padding bits are added and transmitted. Meanwhile, if the STA MLD has no data to transmit over the link through which the request frame was transmitted to the AP MLD that transmitted the request frame, it does not transmit a response to the request frame. Meanwhile, the STA MLD receives the request frame and senses the channel state before transmitting the uplink frame. That is, the STA MLD performs carrier sensing during the time from the completion of reception of the request frame to the start of transmission of the uplink frame. The carrier sensing operation includes one or more of energy sensing, virtual sensing via a preamble value of a received frame, and a NAV confirmation operation.

[0390] Meanwhile, in the operation of Figure 29, a frame transmitted on a basic link of an STR-disabled link group is a frame transmitted to the AP MLD, and a frame to be transmitted on a link other than the basic link receives a response frame from the AP MLD (for example, when requesting transmission of an ACK frame or BlockAck frame), and a channel contention process for transmitting the frame is performed as follows.

[0391] Figure 34 shows a seventh embodiment of the present invention, which illustrates another example of an operation in which channel access and frame transmission are performed exceptionally in an extended link when AP MLD is unable to perform STR. In Figure 34, the same or similar operations as those in Figure 29 will not be described.

[0392] 34, when the STA MLD recognizes that another UE is transmitting an uplink frame to the AP MLD through a basic link of the STR-disabled link group, the STA MLD performs a channel contention process to transmit a frame requesting a response within the corresponding transmission time through another link in the corresponding STR-disabled link group. For example, if Link 1, Link 2, and Link 3 are in the STR-disabled link group and Link 2 is the basic link, the STA MLD recognizes a frame transmitted by another UE (e.g., STA 3) through Link 2. At this time, the STA MLD checks the transmission end time and transmitting / receiving UE addresses of the PPDU containing the frame. Alternatively, the STA MLD checks the receiving UE of the PPDU through the preamble in the PPDU containing the frame. For example, if the PPDU containing the frame is an HE PPDU or EHT PPDU, the STA MLD checks whether the UE transmitting the PPDU is another UE through the UL / DL field or BSS color field in the PPDU. That is, if the UL / DL field indicates an uplink PPDU and the BSS color field indicates a BSS corresponding to the base link of the STA MLD, the STA MLD determines that the corresponding PPDU is to be transmitted from another UE to the corresponding AP MLD. Alternatively, if the PPDU containing the corresponding frame is a VHT PPDU, the STA MLD checks whether it is a PPDU transmitted from another UE through the Group ID field and Partial AID field in the PPDU. That is, if the Group ID value in the PPDU is 0 and the Partial AID is the Partial AID set from the BSSID of the AP of the base link, the STA MLD determines that the corresponding PPDU is to be transmitted from another UE to the AP MLD. In this case, the end point of transmission of the PPDU containing the corresponding frame is recognized by checking the L-SIG field in the preamble.

[0393] If the receiving address of a frame transmitted over the basic link is the address of the AP MLD, and the STA MLD recognizes that the PPPDU containing the frame transmitted over the basic link is the PPDU transmitted to the AP MLD, it performs a channel contention process for transmitting the frame over the extended link during the transmission time of the PPDU containing the corresponding frame. At this time, the STA MLD performs a channel contention process for transmitting the frame over the extended link from the time when it recognizes that the PPDU containing the frame is the PPDU to be transmitted to the AP MLD. The channel contention process is a process of performing channel sensing on the extended link during the AIFS and backoff time. At the time when the channel contention process over the extended link is completed, the STA MLD compares the transmission end point of the PPDU containing the frame to be transmitted with the transmission end point of the PPDU containing the frame being transmitted over the basic link. If it is determined that the transmission end point of the PPDU to be transmitted is before the transmission end point of the PPDU being transmitted over the basic link, it transmits the corresponding frame over the extended link. At this time, the transmission end point of the PPDU transmitted over the extended link is aligned with the transmission end point of the PPDU transmitted over the basic link. At this time, a padding field is added to the frame transmitted over the extended link to align the transmission end point. Alternatively, padding bits are added to the PPDU including the frame. At this time, if the frame received over the basic link does not request transmission of a response frame, the AP MLD transmits an arbitrary frame during the corresponding time. At this time, the arbitrary frame is a frame that prevents other terminals from transmitting uplink frames during the corresponding time. For example, the arbitrary frame is a QoS Null frame having a length corresponding to the length of the response frame transmitted over the extended link.

[0394] Meanwhile, in the extension link, only one frame exchange is permitted as a frame transmission operation, that is, consecutive frame exchange operations due to the TXOP acquisition process are not permitted.

[0395] On the other hand, as an exception, if there is only one extension link in the STR-incapable link group, if the frame transmitted on the basic link is a frame transmitted in another BSS, the TXOP is acquired and maintained until the end of transmission of the PPDU containing the frame as follows.

[0396] Figure 35 shows an eighth embodiment of the present invention, which illustrates another example of an exceptional operation in which channel access and frame transmission are performed in an extended link when AP MLD is unable to perform STR. In Figure 35, operations that are the same as or similar to those described in Figure 29 will not be described.

[0397] Referring to Figure 35, when there is only one basic link and one extended link in the STR-disabled link group, if the STA MLD recognizes that a terminal belonging to another BSS is transmitting a frame through the basic link, it performs a channel contention process to transmit the frame through the extended link in the corresponding STR-disabled link group. For example, if Link 1 and Link 2 operated by the AP MLD are in an STR-disabled link group and Link 1 is the basic link, when a frame transmitted from another BSS is recognized through Link 1, the STA MLD performs a channel access operation through Link 2 during the transmission time of the PPDU including the frame. At this time, the STA MLD recognizes that the frame is transmitted from another BSS based on the transmitting and receiving addresses of the frame received through the basic link. For example, if the transmitting address of the frame is not the address of the AP MLD and the BSSID field is not the BSSID of the AP on the corresponding link, it recognizes that the frame is transmitted from another BSS. At this time, the transmission end time of the PPDU is confirmed based on the L-SIG included in the preamble of the corresponding PPDU.

[0398] Alternatively, the receiving terminal of the corresponding PPDU is identified through the preamble in the PPDU containing the corresponding frame. For example, if the PPDU containing the corresponding frame is an HE PPDU or EHT PPDU, the BSS color field of the corresponding PPDU is used to determine whether the terminal transmitting the corresponding PPDU belongs to another BSS. That is, if the BSS color field indicates a BSS different from the base link of the STA MLD, the corresponding PPDU is determined to be transmitted by a terminal belonging to another BSS. Alternatively, if the PPDU containing the corresponding frame is a VHT PPDU, the Group ID field and Partial AID field in the corresponding PPDU are used to determine whether the PPDU is transmitted by another terminal. For example, if the Group ID value in the corresponding PPDU is 0 and the Partial AID is not 0 or the Partial AID obtained from the BSSID of the AP of the base link, the corresponding PPDU is determined to be transmitted from a terminal of another BSS.

[0399] If the STA MLD recognizes that the corresponding PPDU is a PPDU transmitted from another BSS through the address field and BSSID field of the frame transmitted over the basic link or the preamble of the corresponding PPDU, it performs a channel contention process to transmit a frame over the extended link while the corresponding PPDU is being transmitted. For example, if the STA MLD recognizes a PPDU containing a frame transmitted by a terminal of another BSS over link 1, it performs a channel contention process during the transmission time of the PPDU containing the frame over link 2. After performing the channel contention process, the STA MLD transmits a frame to the AP MLD over the extended link. At this time, the frame requests multiple frame exchange procedures. That is, the frame acquires a TXOP with a length including multiple frame exchange procedures. At this time, the TXOP end time is set to be before the end of the transmission of the PPDU containing the frame being transmitted over the basic link. On the other hand, if it is not possible to determine whether the frame or PPDU transmitted on the basic link was transmitted by a terminal of another BSS, or if the end point of transmission of the frame and response frame transmitted after the channel contention process on the extension link is expected to be after the end point of transmission of the PPDU on the basic link, the STA MLD does not transmit the frame on the corresponding extension link.

[0400] The AP MLD recognizes that a terminal belonging to another BSS is transmitting a frame via the basic link, or receives a frame transmitted via the extended link via the STA MLD, and transmits a response frame to the frame received via the extended link.

[0401] Meanwhile, in Figure 35, the channel access procedure by frame transmission in another BSS in the basic link is also performed when there is more than one extension link in the STR-disabled link group. In this case, the exceptional frame transmission operation is performed for all extension links when performing channel access for the extension links in Figure 24. In this case, frame transmission in the STA MLD is performed only when the channel contention process is completed for all extension links in the STR-disabled link group and simultaneous transmission operation is possible as shown in Figure 31(b).

[0402] Meanwhile, the AP MLD and STA MLD configure the data corresponding to all Traffic IDs (TIDs) to be transmitted to all links after the negotiation process for multi-link operation. In this case, the AP MLD and STA MLD configure the data corresponding to a specific Traffic ID (TID) to be transmitted only to some links during or after the negotiation process for multi-link operation. For example, data with TID 1 is configured to be transmitted to all links, and data with TID 2 is configured to be transmitted only to some links. In other words, a specific TID is mapped to be transmitted only to some links. In this case, if the AP MLD is an MLD that cannot perform STR operation on some links, it configures the TID to be transmitted to some links as follows:

[0403] FIG. 36 illustrates an embodiment of a mapping process for transmitting a specific TID from some links using the concept of a basic link when the AP MLD is unable to perform STR operation.

[0404] Referring to Figure 36, if the AP MLD is unable to perform STR, the corresponding AP MLD sets one link in the STR-incapable link group as the primary link. At this time, the STA MLD negotiates with the corresponding AP MLD for the use of multiple links as shown in Figure 14. At this time, the STA MLD and AP MLD set all Traffic ID (TID) data to be transmitted to all links. Alternatively, they set TID data to be transmitted only to a specific link. At this time, if the AP MLD is unable to perform STR on some or all links, if a specific TID is mapped to an extended link in the STR-incapable group, the corresponding TID should also be mapped to be transmitted to the primary link in the STR-incapable link group. In other words, it is not possible to set a specific TID to be transmitted only to an extended link in the STR-incapable link group.

[0405] For example, the AP MLD is a link where STR operation is not possible. The AP MLD configures link 1 as the primary link between link 1 and link 2, where STR operation is not possible. In this case, when the AP MLD and STA MLD are activating multiple link operation and attempting to transmit data with TID 1, 2, or 3, data of all TIDs is allowed to be transmitted over all links unless the AP MLD and STA MLD perform a separate mapping process. In this case, the STA MLD transmits a request frame to the AP MLD requesting that the TID be mapped to a specific link in order to restrict the links over which data of a specific TID is transmitted. In this case, if a TID set in the request frame to be transmitted over an extended link is not set to be transmitted over a primary link in the corresponding STR-incapable link group, transmission of the corresponding frame is not allowed. For example, the request frame cannot be configured to transmit data with TIDs 1 and 2 over link 1, which is the primary link, and data with TID 3 over link 2. On the other hand, if the AP MLD receives the request frame from the STA MLD, the AP MLD confirms that the data with TID 3 is requested to be transmitted over the extension link but not over the basic link, and then transmits a response frame rejecting the request.

[0406] Meanwhile, when the STA MLD requests that a specific TID be mapped to a specific link, it requests that all TIDs transmitted over the extension link be mapped so that they can be transmitted over the basic link. For example, the STA MLD requests that data with TID 1, 2, or 3 be transmitted over link 1, and data with TID 1 be transmitted over link 2 as well. The AP MLD that received the request frame receives a mapping request frame from the STA MLD. At this time, it confirms that TID 1, which is mapped to link 2 (the extension link), is also mapped to link 1 (the basic link) according to the content included in the request frame. Therefore, the AP MLD transmits a response frame to the STA MLD, accepting the request frame.

[0407] Alternatively, the process of mapping a specific TID to the extended link is not performed, i.e., the extended link is not a target link to which a TID is mapped. In this case, the process of setting a specific TID to be transmitted only on some links is performed only on the basic link.

[0408] FIG. 37 is a flow chart illustrating an example of a method for channel access in accordance with the present invention.

[0409] Referring to FIG. 37, non-AP MLD performs the same operations for channel access as AP MLD, but transmits and receives frames for channel access only via a specific link.

[0410] In detail, non-AP MLD and AP MLD are composed of multiple logical entities. In this case, AP MLD is an NSTR soft AP MLD, and for AP MLD to operate as an NSTR soft AP MLD, the number of links supporting NSTR must be less than a certain number.

[0411] That is, a non-AP MLD is composed of a plurality of stations, and one of the plurality of STAs constituting the non-AP MLD forms the basic link with one of the plurality of APs constituting the AP MLD.

[0412] The remaining STAs, excluding one STA among the plurality of STAs constituting the non-AP MLD, form the at least one extended link with the remaining APs, excluding the one AP among the plurality of APs constituting the AP MLD.

[0413] Non-AP STA transmits a probe request frame for channel access from AP MLD,

[0414] The AP MLD receives the beacon frame for the access in step S36010. At this time, the AP MLD has a plurality of links configured, each of which includes one basic link and at least one extended link. The beacon frame is transmitted and received via the basic link.

[0415] If the probe request frame is transmitted via the basic link, a probe response frame is received as a response to the probe request frame via the basic link (S36020).

[0416] At this time, the beacon frame and the response frame are received only through the basic link, excluding the at least one extension link.

[0417] If a probe request frame is transmitted over the at least one extension link, the AP MLD does not transmit a probe response frame, which is a response to the probe request frame, over the at least one extension link.

[0418] At this time, link information regarding the links formed between the AP MLD and the non-AP MLD is received from the AP MLD, and the link information includes a bitmap indicating the number of the multiple links formed between the non-AP MLD and the AP MLD and whether each of the multiple links supports the STR operation.

[0419] According to AP MLD, the basic link and the at least one extension link do not support STR.

[0420] In addition, the non-AP MLD transmits an association request frame to the AP MLD, and the AP MLD transmits an association response frame in response to the association request frame. At this time, the association request frame and the association response frame are transmitted only via the basic link as described above.

[0421] Therefore, if the non-AP MLD transmits an association request frame via a non-primary link, which is an extension link, rather than via a primary link, which is a basic link, the AP MLD does not transmit an association response frame in response thereto.

[0422] Next, non-AP MLD transmits PPDUs (physical layer protocol data units) to AP MLD via the configured basic link and / or at least one extension link. In this case, non-AP MLD transmits PPDUs via extension links only when it occupies the primary link. In other words, PPDU transmission via extension links is dependent on the primary link. In addition, non-AP MLD sets the PPDU transmission start time for the primary link and extension links to be the same using an offset. In other words, the PPDU transmission start time is the same for the primary link and at least one extension link.

[0423] The above-mentioned method of setting the same transmission start time for the PPDU in the main link and at least one extension link applies not only to the method in which a non-AP MLD transmits a PPDU to an AP MLD, but also to the method in which an AP MLD transmits a PPDU to a non-AP MLD.

[0424] That is, when an AP MLD transmits a PPDU to a non-AP MLD via a basic link and at least one extended link, the transmission start times of the PPDUs transmitted via the basic link and at least one extended link are set to be the same.

[0425] In addition, the link information further includes information such as a link ID in addition to the above information as described above.

[0426] In the embodiments described in the present invention, the embodiments relating to association (e.g., an embodiment of transmitting a beacon frame and a probe response frame in an association procedure and / or an embodiment of transmitting an association request frame) also apply to reassociation.

[0427] For example, when sending and receiving beacon frames, probe request frames, and probe response frames for reassociation, they can only be sent and received via the primary link, and when sending and receiving reassociation request frames and reassociation response messages for reassociation, the frames can only be sent and received via the primary link.

[0428] The above description of the present invention is for illustrative purposes only, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and are not limiting. For example, each component described as a single component may be implemented in a distributed form, and components described as distributed may also be implemented in a combined form.

[0429] The scope of the present invention is indicated by the claims that follow rather than by the above detailed description, and all modifications and variations that fall within the meaning and scope of the claims and their equivalents should be interpreted as being included within the scope of the present invention. [Explanation of symbols]

[0430] 100 Stations 110 processors 120 Communications Department 140 User Interface 150 display units 160 memory 210 processors 220 Communications Department 260 memory 300 servers

Claims

1. A non-access point multilink device (non-AP MLD) in a wireless communication system, Communication module and A processor configured to control the aforementioned communication module The processor includes, Establish links to AP MLD, including a primary link and one or more non-primary links. The AP MLD receives a beacon frame via the main link. It is configured in such a way, If none of the traffic identifiers (TIDs) associated with traffic transmission are mapped to one or more non-primary links, then all of the TIDs are associated with the primary links in the non-AP MLD.

2. The processor The probe request frame associated with the AP MLD is transmitted. It is configured in such a way, The non-AP MLD according to claim 1, wherein the primary link and the one or more non-primary links operate as an asynchronous transmit / receive (NSTR) link pair, which is a pair of links where simultaneous transmission on one link and reception on the other is not supported.

3. The processor When the probe request frame is transmitted through the main link, the frame transmitted through the main link responds to the probe request frame by receiving a probe response frame. The non-AP MLD according to claim 2, configured as described above.

4. The non-AP MLD according to claim 3, wherein the beacon frame and the probe response frame are received only through the primary link of the plurality of links.

5. The non-AP MLD according to claim 2, wherein the AP MLD operates as an NSTR soft AP MLD, and the number of links set up by the AP MLD is less than or equal to a specific number.

6. The non-AP MLD comprises a plurality of non-AP stations (STAs), One of the multiple non-AP STAs constituting the non-AP MLD sets up the main link with one of the multiple APs constituting the AP MLD. A non-AP STA among the plurality of non-AP STAs that does not include the one non-AP STA sets up one or more non-primary links with an AP among the plurality of APs that does not include the one AP. The non-AP MLD according to claim 1.

7. The processor The AP MLD is configured to receive link information related to the multiple links set up between the AP MLD and the non-AP MLD. The link information comprises at least one of the following: i) the number of the plurality of links set between the non-AP MLD and the AP MLD, and ii) a bitmap indicating whether each of the plurality of links supports STR operation. The non-AP MLD according to claim 6.

8. The processor It is configured to transmit Physical Layer Protocol Data Units (PPDUs) to the AP MLD through the primary link and at least one of the one or more non-primary links that have been activated. The PPDU and the transmission start time points of the at least one activated link are the same in the main link. The non-AP MLD according to claim 1.

9. A method for performing association by a non-access point multilink device (non-AP MLD) in a wireless communication system, The steps include establishing links to AP MLD with multiple links, including a primary link and one or more non-primary links, The steps include receiving a beacon frame from the AP MLD via the main link, and Equipped with, A method in which, if none of the traffic identifiers (TIDs) associated with traffic transmission are mapped to the one or more non-primary links, all of the TIDs are associated with the primary link.

10. The step of transmitting a probe request frame associated with the AP MLD. Furthermore, The method according to claim 9, wherein the primary link and the one or more non-primary links operate as an non-simultaneous transmit / receive (NSTR) link pair, which is a pair of links where simultaneous transmission on one link and reception on the other is not supported.

11. The method according to claim 10, further comprising the step of receiving a probe response frame in response to the probe request frame transmitted through the main link when the probe request frame is transmitted through the main link.

12. The method according to claim 11, wherein the beacon frame and the probe response frame are received only through the main link of the plurality of links.

13. The method according to claim 10, wherein the AP MLD operates as an NSTR soft AP MLD, and the number of the plurality of links set up by the AP MLD is less than or equal to a specific number.

14. The non-AP MLD comprises a plurality of non-AP stations (STAs), One of the multiple non-AP STAs constituting the non-AP MLD sets up the main link with one of the multiple APs constituting the AP MLD. A non-AP STA among the plurality of non-AP STAs that does not include the one non-AP STA sets up one or more non-primary links with an AP among the plurality of APs that does not include the one AP. The method according to claim 9.

15. The claim further comprises the step of receiving link information from the AP MLD relating to the plurality of links set up between the AP MLD and the non-AP MLD, The link information comprises at least one of the following: i) the number of the plurality of links set between the non-AP MLD and the AP MLD, and ii) a bitmap indicating whether each of the plurality of links supports STR operation. The method according to claim 14.

16. The further step is to transmit a physical layer protocol data unit (PPDU) to the AP MLD through the primary link and at least one of the one or more non-primary links that have been activated. The PPDU and the transmission start time points of the at least one activated link are the same in the main link. The method according to claim 9.

17. The processor The non-AP STA included in the non-AP MLD is further configured to receive Physical Layer Protocol Data Units (PPDUs), The PPDU includes a Basic Service Set (BSS) color and a PHY version identifier. i) If the BSS color of the PPDU is the same as the BSS color of the BSS to which the non-AP STA is associated, and ii) if the PHY version identifier is different from the intended value, the non-AP STA enters a hibernation state. The non-AP MLD according to claim 1.

18. The non-AP STA included in the non-AP MLD further comprises the step of receiving a physical layer protocol data unit (PPDU), The PPDU includes a Basic Service Set (BSS) color and a PHY version identifier. i) If the BSS color of the PPDU is the same as the BSS color of the BSS to which the non-AP STA is associated, and ii) if the PHY version identifier is different from the intended value, the non-AP STA enters a hibernation state. The method according to claim 9.

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