Wireless communication method using multilink and wireless communication terminal using the same

Abstract

To provide a multilink device using multiple links.SOLUTION: A multilink device includes a transceiver and a processor, and when the multilink device transmits a plurality of PPDUs simultaneously over a plurality of links using the transceiver, the processor determines a transmission end time of the plurality of PPDUs on the basis of whether the multilink device transmits a frame requesting an ACK.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a wireless communication method using multilinks and a wireless communication terminal using the same. [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 since implemented or is currently developing various other technology standards. IEEE 802.11b uses the 2.4 GHz frequency band and supports a maximum communication speed of 11 Mbps. IEEE 802.11a, which was commercialized after IEEE 802.11b, uses the 5 GHz frequency band instead of the 2.4 GHz band, reducing the impact of interference compared to the significantly more congested 2.4 GHz frequency band, and uses OFDM technology to improve communication speeds to a maximum of 54 Mbps. However, IEEE 802.11a has the disadvantage of a shorter communication distance than IEEE 802.11b. IEEE 802.11g, like IEEE 802.11b, uses the 2.4GHz band and achieves a maximum transmission speed of 54Mbps, and has attracted considerable attention for its 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) with data processing speeds 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 a new WLAN standard 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 being developed with the goal of supporting transmission rates of up to 30Gbps in the 2.4 / 5 / 6GHz bands through wider bandwidth, increased spatial streams, and multi-AP cooperation. Summary of the Invention [Problem to be solved by the invention]

[0008] An object of one embodiment of the present invention is to provide a wireless communication method using multilinks and a wireless communication terminal using the same. [Means for solving the problem]

[0009] According to one embodiment of the present invention, a multi-link device using multiple links includes a transceiver unit and a processor, and when the multi-link device transmits multiple PPDUs simultaneously over multiple links using the transceiver unit, the processor determines a transmission end time for the multiple PPDUs based on whether the multi-link device transmits a frame requesting ACK.

[0010] When the multi-link device transmits multiple PPDUs simultaneously over multiple links, the processor may align the ends of multiple PPDUs that require ACK among the multiple PPDUs.

[0011] When the multi-link device transmits multiple PPDUs simultaneously over multiple links, the processor may not align the end of a PPDU among the multiple PPDUs that includes only frames that do not request ACK with the end of a PPDU among the multiple PPDUs that includes frames that request ACK.

[0012] Specifically, when the multi-link device transmits multiple PPDUs simultaneously over multiple links, the processor transmits the multiple PPDUs such that the end of a PPDU containing only frames that do not request ACK is not delayed from the end of a PPDU containing frames that request ACK.

[0013] Whether the frame requiring ACK is a frame requiring ACK or not may be determined based on an ACK policy.

[0014] The frame requesting ACK may be a data frame.

[0015] The multilink device is an AP multilink device, and the processor can transmit the plurality of PPDUs to a non-AP multilink device using the transceiver unit.

[0016] A multi-link device receiving the multiple PPDUs may be unable to receive on any other link when transmitting on any one of the links.

[0017] According to an embodiment of the present invention, a multi-link device using multiple links includes a transceiver unit and a processor. The processor receives multiple PPDUs simultaneously via multiple links using the transceiver unit. The processor determines a transmission end time of the multiple PPDUs based on whether a frame requesting ACK is transmitted in the multiple PPDUs.

[0018] Among the plurality of PPDUs, the ends of the plurality of PPDUs requesting ACK may be aligned.

[0019] The end of a PPDU including only frames that do not request ACK among the plurality of PPDUs may not be aligned with the end of a PPDU including frames that request ACK among the plurality of PPDUs.

[0020] Specifically, the end of a PPDU including only frames that do not request ACK among the plurality of PPDUs may not be delayed from the end of a PPDU including frames that request ACK among the plurality of PPDUs.

[0021] Whether the frame requiring ACK is a frame requiring ACK or not may be determined based on an ACK policy.

[0022] The frame requesting ACK may be a data frame.

[0023] The multilink device is a non-AP multilink device, and the processor can transmit the plurality of PPDUs from the AP multilink device using the receiver.

[0024] The multi-link device may be such that when transmitting on one link, it is not possible to receive on the other links.

[0025] The processor may access the channels in the plurality of links by a channel access method using a backoff counter. In this case, the backoff counter may have an initial value set by an acquired random number, may be decremented by 1 when the channel to be accessed during a slot time is idle, and may allow the terminal to access the channel when the backoff counter value is 0. The processor may not transmit on any one of the plurality of links even if the backoff counter reaches 0 during channel access on the one of the plurality of links.

[0026] When no transmission occurs on any one of the links, the processor can maintain the value of the backoff counter.

[0027] According to an embodiment of the present invention, a method for operating a multi-link device using multiple links includes the step of receiving multiple PPDUs simultaneously via multiple links using the transceiver unit of the multi-link device, and determining a transmission end time of the multiple PPDUs based on whether a frame requesting ACK is transmitted in the multiple PPDUs.

[0028] Among the plurality of PPDUs, the ends of the plurality of PPDUs requesting ACK may be aligned. [Effects of the Invention]

[0029] An embodiment of the present invention provides a wireless communication method that efficiently uses multilinks and a wireless communication terminal that uses the same. [Brief explanation of the drawings]

[0030] [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 shows a multi-link device according to an embodiment of the present invention; [Figure 10] 1 illustrates a case where transmissions on different links are performed simultaneously in a multi-link operation according to an embodiment of the present invention. [Figure 11] 10 illustrates an operation in which a multi-link device according to an embodiment of the present invention simultaneously completes transmission on multiple links. [Figure 12] 10 illustrates an operation of the multilink device according to an embodiment of the present invention, in which the multilink device finishes transmission on one of the links first when the multilink device transmits on a plurality of links. [Figure 13] This shows that when a multi-link device according to an embodiment of the present invention transmits on one link, the multi-link device postpones transmission on the other links. [Figure 14] 10 illustrates an operation of the multilink device according to an embodiment of the present invention, in which the multilink device finishes transmission on one of the links first when the multilink device transmits on a plurality of links. [Figure 15] 10 shows an operation of the multilink device according to still another embodiment of the present invention, in which the multilink device finishes transmission on one of the links first when transmitting on a plurality of links. [Figure 16] 1 illustrates how a multilink device according to an embodiment of the present invention operates using a mapping between links and TIDs. [Figure 17] 10 illustrates an operation of a station performing UL MU transmission according to an embodiment of the present invention. [Figure 18] 10 illustrates a multi-link device according to an embodiment of the present invention collecting multi-TIDs. [Figure 19] 10 illustrates elements that signal information about link-to-TID mapping according to an embodiment of the present invention. [Figure 20] 10 shows a station according to an embodiment of the present invention accessing a channel to transmit a trigger frame. [Figure 21] 1 illustrates an operation of a multi-link device transmitting over multiple links according to an embodiment of the present invention. [Figure 22] 10 illustrates an operation of setting NAV by a multi-link device according to an embodiment of the present invention. [Figure 23] 10 illustrates an operation of setting NAV by a multi-link device according to an embodiment of the present invention. [Figure 24] 10 shows that a station in a multi-link device according to an embodiment of the present invention resumes channel access or transmission after suspending channel access or transmission due to a PPDU received by another station in the multi-link device. [Figure 25] 10 shows a method for transmitting a response to a trigger frame when a NAV is set in the multilink device according to an embodiment of the present invention and the multilink device receives a trigger frame. DETAILED DESCRIPTION OF THE INVENTION

[0031] 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 may have 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.

[0032] 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 another component, but also when the component is "electrically connected" to another component via another component in between. Furthermore, when a component is referred to as "comprising" a specific component, this does not mean that the component may exclude the other component, but may further include the other component, unless otherwise specified. In addition, 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.

[0033] Hereinafter, in the present invention, the terms field and subfield may be used interchangeably.

[0034] FIG. 1 is a diagram showing a wireless LAN system according to an embodiment of the present invention.

[0035] 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.

[0036] 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.

[0037] 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).

[0038] 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.

[0039] 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).

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] Next, the display unit 150 outputs an image on a display screen. The display unit 150 outputs various display objects, such as a user interface, based on the contents processed by the processor 110 or the 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.

[0046] 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.

[0047] 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 mounted 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 mounted 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 provided in the station 100.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] FIG. 5 is a diagram illustrating a process in which a STA establishes a link with an AP.

[0052] 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 transmits a probe request to the AP S103, receives a probe response from the AP S105, and acquires connection information.

[0053] The STA 100 that successfully receives wireless connection information in the scanning step transmits an authentication request (S107a), receives an authentication response from the AP 200, and performs the authentication step (S107b). 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 association and wired association.

[0054] 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.

[0055] FIG. 6 is a diagram showing a CSMA (Carrier Sense Multiple Access) / CA (Collision Avoidance) method used in wireless LAN communication.

[0056] 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.

[0057] If the channel is determined to be idle, each terminal having data to transmit performs a backoff procedure after an Inter Frame Space (IFS), such as an Arbitration IFS (AIFS) or a PCF IFS (PIFS), depending on the status of each terminal. In some embodiments, the AIFS is used as a configuration replacing the conventional DCF IFS (DIFS). Each terminal waits while decrementing a slot time equal to a random number determined for the corresponding terminal during the idle interval of the channel, and a terminal that has exhausted all of its slot time attempts to access the corresponding channel. The period during which each terminal performs the backoff procedure is called a contention window period. In this case, the random number can be called a backoff counter. That is, the initial value of the backoff counter is set by an integer, which is a random number obtained by the terminal. If the terminal detects that the channel is idle during the slot time, the terminal can decrement the backoff counter by 1. If the backoff counter reaches 0, the terminal may be allowed to perform channel access on the corresponding channel. Therefore, if the channel is idle during the AIFS time and the backoff counter slot time, the terminal may be allowed to transmit.

[0058] 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.

[0059] <Examples of various PPDU formats>

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] The unit of the L_LENGTH field is byte, and a total of 12 bits are allocated, allowing signaling up to 4095. In combination with the L_RATE field, the length of the PPDU can be indicated. In this case, legacy and non-legacy terminals can interpret the L_LENGTH field in different ways.

[0067] First, a legacy or non-legacy terminal analyzes the length of the PPDU using the L_LENGTH field as follows. When the L_RATE field is set to 6 Mbps, 3 bytes (i.e., 24 bits) may be transmitted at 4 us, which is the duration of one symbol of the 64FFT. Therefore, by adding 3 bytes corresponding to the SVC field and the 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 reference symbols for the 64FFT after the L-SIG is obtained. The obtained number of symbols is multiplied by 4 us, which is the duration of one symbol, and then 20 us, which is required to transmit the L-STF, L-LTF, and L-SIG, is added to obtain the length of the PPDU, i.e., the reception time (RXTIME). This can be expressed mathematically as shown in Equation 1 below.

[0068]

number

[0069] At this time,

number

[0070]

number

[0071] 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.

[0072]

number

[0073] 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.

[0074] 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.

[0075] 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 generation 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.

[0076] 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.

[0077] 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 in the same PPDU format, and a field for distinguishing between MU PPDUs and SU PPDUs may be located before the EHT-SIG field, and additional signaling may be performed for this purpose. 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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, or 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.

[0083] This invention proposes a method for signaling the discontinuous channel type of an SU PPDU and illustrates the discontinuous channel type determined by the proposed method. It also proposes a method for signaling the primary 160 MHz and secondary 160 MHz puncturing types in a 320 MHz BW configuration of an SU PPDU. The discontinuous channel types allowed when the above discontinuous channel type definition method is applied and a method for signaling the discontinuous channel type with 3 bits are shown in Figures 17 to 19.

[0084] In addition, one embodiment of the present invention proposes a method of varying the PPDU configuration indicated by the preamble puncturing BW value depending on the PPDU format signaled in the PPDU format field. Assuming that the BW field is 4 bits, in the case of an EHT SU PPDU or TB PPDU, an EHT-SIG-A symbol can be further signaled after the U-SIG, or no EHT-SIG-A can be signaled at all. Taking this into consideration, up to 11 puncturing modes must be fully 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 can be signaled in a different manner than in the case of an 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. Detailed puncturing patterns for each PPDU type will be described in detail below with reference to FIGS. 11 and 12.

[0085] 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.

[0086] FIG. 8 illustrates an example of 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] For ease of explanation, the term frame or MAC frame may be used interchangeably with MPDU in this specification.

[0096] When a single wireless communication device communicates using multiple links, the communication efficiency of the wireless communication device can be improved. In this case, a link is a physical path and may be configured as a single wireless medium that can be used to transmit an MSDU (MAC service data unit). For example, when the frequency band of one link is being used by another wireless communication device, the wireless communication device can continue communication using another link. In this way, the wireless communication device can effectively use multiple channels. Furthermore, when a wireless communication device simultaneously communicates using multiple links, the overall throughput can be improved. However, existing wireless LANs are specified on the assumption that one wireless communication device uses one link. Therefore, a wireless LAN operation method for using multiple links is needed. A wireless communication method for a wireless communication device using multiple links will be described with reference to FIGS. 9 to 26. First, a specific embodiment of a wireless communication device using multiple links will be described with reference to FIG. 9.

[0097] FIG. 9 shows a multi-link device according to an embodiment of the present invention.

[0098] A multi-link device (MLD) may be defined for the wireless communication method using multiple links described above. The multi-link device may represent a device having one or more affiliated stations. Depending on a specific embodiment, the multi-link device may represent a device having two or more affiliated stations. The multi-link device may also exchange multi-link elements. The multi-link element includes information about one or more stations or one or more links. The multi-link element may include a multi-link setup element, which will be described later. In this case, the multi-link device may be a logical entity. Specifically, the multi-link device may have multiple affiliated stations. The multi-link device may be referred to as a multi-link logical entity (MLLE) or a multi-link entity (MLE). The multi-link device may have one medium access control service access point (SAP) up to a logical link control (LLC). The MLD may also have one MAC data service.

[0099] Multiple stations included in a multilink device can operate on multiple links. Also, multiple stations included in a multilink device can operate on multiple channels. Specifically, multiple stations included in a multilink device can operate on different links or different channels. For example, multiple stations included in a multilink device can operate on different channels, such as 2.4 GHz, 5 GHz, and 6 GHz.

[0100] The operation of the multilink device can be referred to as multilink operation, MLD operation, or multi-band operation. If the station associated with the multilink device is an AP, the multilink device can be referred to as AP MLD. If the station associated with the multilink device is a non-AP station, the multilink device can be referred to as non-AP MLD.

[0101] FIG. 9 shows the operation of communication between non-AP MLD and AP-MLD. Specifically, non-AP MLD and AP-MLD each communicate using three links. AP MLD includes a first AP (AP1), a second AP (AP2), and a third AP (AP3). Non-AP MLD includes a first non-AP STA (non-AP STA1), a second non-AP STA (non-AP STA2), and a third non-AP STA (non-AP STA3). The first AP (AP1) and the first non-AP STA (non-AP STA1) communicate via a first link (Link1). The second AP (AP2) and the second non-AP STA (non-AP STA2) communicate via a second link (Link2). The third AP (AP3) and the third non-AP STA (non-AP STA3) communicate via a third link (Link3).

[0102] Multilink operation may include a multilink setup operation. Multilink setup corresponds to the association operation of the single-link operation described above and must be performed prior to frame exchange in the multilink. A multilink device can obtain information required for multilink setup from a multi-link setup element. Specifically, the multi-link setup element may include capability information related to the multilink. In this case, the capability information may include information indicating whether one of multiple devices included in the multilink device can transmit and the other devices can receive at the same time. The capability information may also include information about links available to each station included in the MLD. The capability information may also include information about channels available to each station included in the MLD.

[0103] Multilink configuration may be established through negotiation between peer stations. Specifically, multilink configuration may be established through communication between stations without communication with an AP. Multilink configuration may also be established through any one of the links. For example, even if the first to third links are established through multilink, multilink configuration may be established through the first link.

[0104] In addition, a mapping between a traffic identifier (TID) and a link may be configured. Specifically, frames corresponding to a specific TID value may be exchanged only through a pre-specified link. The mapping between a TID and a link may be configured on a directional basis. For example, when multiple links are configured between a first multilink device and a second multilink device, the first multilink device may be configured to transmit frames of the first TID to the multiple first links, and the second multilink device may be configured to transmit frames of the second TID to the first links. In addition, a default setting may exist for the mapping between TIDs and links. Specifically, if no additional settings are configured in the multilink configuration, the multilink device may exchange frames corresponding to TIDs on each link according to a default setting. In this case, the default setting may be that all TIDs are exchanged on any one link.

[0105] The TID will be described in detail. The TID is an ID for classifying traffic and data to support quality of service (QoS). The TID may be used and assigned in a layer higher than the MAC layer. The TID may indicate a traffic category (TC) or a traffic stream (TS). There may be 16 distinct TIDs. For example, the TID may be designated as any one of 0 to 15. Different TID values ​​may be designated depending on an access policy, a channel access method, or a medium access method. For example, when enhanced distributed channel access (EDCA) or hybrid coordination function contention-based channel access (HCAF) is used, the TID may be assigned a value ranging from 0 to 7. When EDCA is used, the TID may indicate a user priority (UP). In this case, the UP may be designated by the TC or the TS. The UP may be assigned in a layer higher than the MAC. Furthermore, when HCCA (HCF controlled channel access) or SPCA is used, the TID may be assigned a value in the range of 8 to 15. When HCCA or SPCA is used, the TID may indicate a TSID. Furthermore, when HEMM or SEMM is used, the TID may be assigned a value in the range of 8 to 15. When HEMM or SEMM is used, the TID may indicate a TSID.

[0106] UP and AC (access category) may be mapped. AC may be a label for providing QoS in EDCA. AC may be a label for indicating an EDCA parameter set. EDCA parameters or EDCA parameter sets are parameters used in EDCA channel contention. QoS stations can guarantee QoS using AC. AC may include AC_BK, AC_BE, AC_VI, and AC_VO. AC_BK, AC_BE, AC_VI, and AC_VO may indicate background, best effort, video, and voice, respectively. AC_BK, AC_BE, AC_VI, and AC_VO may be classified into lower-level ACs. For example, AC_VI may be further subdivided into AC_VI primary and AC_VI alternate. AC_VO may be further subdivided into AC_VO primary and AC_VO alternate. UP or TID may be mapped to an AC. For example, 1, 2, 0, 3, 4, 5, 6, and 7 in UP or TID may be mapped to AC_BK, AC_BK, AC_BE, AC_BE, AC_VI, AC_VI, AC_VO, and AC_VO, respectively. Also, 1, 2, 0, 3, 4, 5, 6, and 7 in UP or TID may be mapped to AC_BK, AC_BK, AC_BE, AC_BE, AC_VI alternate, AC_VI primary, AC_VO primary, and AC_VO alternate, respectively. Also, 1, 2, 0, 3, 4, 5, 6, and 7 in UP or TID may have decreasing priority in that order. That is, 1 may have a lower priority, and 7 may have a higher priority. Therefore, the order of priority may be AC_BK, AC_BE, AC_VI, and AC_VO. Also, AC_BK, AC_BE, AC_VI, and AC_VO can correspond to ACI (AC index) 0, 1, 2, and 3, respectively. Due to the characteristics of TID, the mapping between TID and link can represent the mapping between AC and link.The mapping between links and ACs can also represent the mapping between TIDs and links.

[0107] As described above, a TID may be mapped to each of multiple links. The mapping may specify the links through which traffic corresponding to a specific TID or AC can be exchanged. Furthermore, the TID or AC that can be transmitted for each transmission direction within a link may be specified. As described above, a default setting may exist for the mapping between TIDs and links. Specifically, if no additional settings are configured in the multilink configuration, the multilink device may exchange frames corresponding to the TID on each link according to the default setting. In this case, the default setting may be that all TIDs are exchanged on any one link. At any given time, any TID or AC may be mapped to at least one link. Management frames and control frames may be transmitted on all links.

[0108] When a link is mapped to a TID or AC, only data frames corresponding to the TID or AC mapped to the link may be transmitted on the link. Therefore, when a link is mapped to a TID or AC, frames not corresponding to a TID or AC not mapped to the link may not be transmitted on the link. When a link is mapped to a TID or AC, an ACK may also be transmitted based on the link to which the TID or AC is mapped. For example, a Block ACK agreement may be determined based on the mapping between the TID and the link. In yet another specific embodiment, the mapping between the TID and the link may be determined based on the Block ACK agreement. Specifically, a Block ACK agreement may be set for a TID mapped to a specific link.

[0109] The above-described TID-to-link mapping may ensure QoS. Specifically, a high-priority AC or TID may be mapped to a link where a relatively small number of stations are active or where channel conditions are good. The above-described TID-to-link mapping may also allow stations to remain in a power-saving state for a longer period of time.

[0110] FIG. 10 illustrates simultaneous transmission of different links in multi-link operation according to an embodiment of the present invention.

[0111] Depending on the implementation of a multilink device, simultaneous transmission on multiple links, simultaneous reception on multiple links, or transmission on one link and simultaneous reception on another link may not be supported. This is because reception or transmission on one link may affect reception or transmission on another link. Specifically, transmission on one link may interfere with other links. Interference from one link of a multilink device affecting other links may be called internal leakage. The smaller the frequency spacing between links, the greater the internal leakage. If the internal leakage is not too large, transmission on one link may occur while transmission on another link occurs. If the internal leakage is large, transmission on one link may not occur while transmission on another link occurs. In this way, simultaneous transmission on multiple links, transmission on one link and simultaneous reception on another link, or simultaneous reception on multiple links by a multilink device may be called simultaneous transmit and receive (STR). As described above, a multilink device may not support STR. In yet another specific embodiment, the multilink device may support STR in a limited manner. Specifically, the multilink device may support STR only under specific conditions. For example, if the multilink device operates with a single radio, STR may not be performed by the multilink device. Also, if the multilink device operates with a single antenna, STR may not be performed by the multilink device. Also, if internal leakage is detected to be greater than a predetermined value, STR may not be performed by the multilink device.

[0112] A station may exchange information regarding its STR capability with another station. Specifically, a station may exchange information regarding whether the station's ability to transmit or receive on multiple links is limited. Specifically, the information regarding whether the station's ability to transmit or receive on multiple links is limited may indicate whether simultaneous transmission or reception is possible on multiple links, or whether simultaneous transmission and reception are possible. Furthermore, the information regarding whether the station's ability to transmit or receive on multiple links is limited may be information indicating a level of inner leakage. Specifically, the information regarding whether the station's ability to transmit or receive on multiple links is limited may be information indicating a level of inner leakage. In a specific embodiment, the information indicating a level of inner leakage may be information indicating a level of interference caused by inner leakage. In yet another specific embodiment, the information indicating a level of frequency spacing between links that may affect inner leakage may be information indicating a level of inner leakage. Furthermore, the information indicating a level of inner leakage may be information indicating a level of the relationship between the frequency spacing between links and the level of inner leakage.

[0113] In FIG. 10, a first station (STA1) and a second station (STA2) are associated with one non-AP multilink device. A first AP (AP1) and a second AP (AP2) may also be associated with one non-AP multilink device. A first link (link1) is established between the first AP (AP1) and the first station (STA1), and a second link (link2) is established between the second AP (AP2) and the second station (STA2). The non-AP multilink device may perform STR in a limited manner. When the second station (STA2) transmits on the second link (link2), the first station (STA1) may be interfered with receiving on the first link (link1). For example, the second station (STA2) transmits first data (Data1) on the second link (Link2), and the first AP (AP1) transmits a response (Ack for Data1) to the first station (STA1). A second station (STA2) transmits second data (Data2) over a second link (Link2). At this time, the transmission of the second data (Data2) and the transmission of a response (Ack for Data1) to the first data (Data1) may overlap. In this case, the transmission to the second station (STA2) over the second link (Link2) may cause interference to the first link (Link1). As a result, the first station (STA1) may not receive the response (Ack for Data1) to the first data (Data1). Figure 10(a) shows a case where transmission begins simultaneously over multiple links. However, as shown in Figure 10(b), transmission may begin over multiple links at different times.

[0114] Specifically, a multilink device can independently perform channel access, e.g., backoff, on multiple links. In this case, the backoff counters on multiple links may reach 0, and transmission may begin simultaneously on multiple links. In yet another specific embodiment, when the backoff counter on one of the links in the multilink device reaches 0, the multilink device may perform energy detection (ED) on that link and other links before performing channel access. If energy above a certain level is not detected, the multilink device may perform channel access on the link on which energy detection was performed. This allows the multilink device to begin transmission simultaneously on multiple links. The threshold value used for energy detection may be smaller than the threshold value used to determine whether to decrement the backoff counter. Furthermore, when determining whether to decrement the backoff counter, a station can detect any type of signal, not just a WLAN signal. Furthermore, in the above-described energy detection, a station can detect any type of signal, not just a WLAN signal. Internal leakage may not be detected as a WLAN signal. In such a case, the station may sense a signal detected due to internal leakage as energy detection. Also, as described above, the threshold value used for energy sensing may be smaller than the threshold value used for determining whether to decrement the backoff counter. Therefore, even while transmission is occurring on another link, the multi-link device can decrement the backoff counter on one of the links, as shown in Figures 10(a) and 10(b).

[0115] The operation method of the multi-link device when there is a limit to the STR will be described with reference to Figures 11 to 25. However, the embodiment of the present invention may also be applied to a multi-link device when there is no limit to the STR.

[0116] 11 to 15 will be used to describe cases where multiple PPDUs are or can be transmitted simultaneously over multiple links. The embodiments described using FIGS. 11 to 15 may also be applied to cases where STR is not possible over multiple links over which multiple PPDUs are transmitted. The embodiments described using FIGS. 11 to 15 may also be applied to cases where a multi-link device receiving multiple PPDUs cannot receive over other links when transmitting over one of the links. The embodiments described using FIGS. 11 to 15 may also be applied to cases where a multi-link device transmitting multiple PPDUs cannot receive over other links when transmitting over one of the links.

[0117] FIG. 11 shows the operation of a multi-link device according to an embodiment of the present invention to simultaneously complete transmission on multiple links.

[0118] When a multilink device transmits through multiple links, the multilink device can simultaneously end transmission through the multiple links. Specifically, the end points of PPDUs transmitted through the multiple links may be the same. This embodiment may be applied not only to cases where the multilink device simultaneously starts transmission through the multiple links, but also to cases where the multilink device does not simultaneously start transmission. This operation may be for a multilink device that cannot simultaneously transmit and receive. For example, this operation may be for a case where a multilink device receiving multiple PPDUs cannot simultaneously transmit and receive. Or, this operation may be for a case where a multilink device transmitting multiple PPDUs cannot simultaneously transmit and receive. Specifically, as shown in FIG. 10(a), this operation may be for preventing a situation where an ACK cannot be received through another link while transmission is being performed through one link. Therefore, if the multilink device does not support reception through another link when transmitting through one link, the multilink device may simultaneously end transmission through the multiple links.

[0119] While a response frame to a multilink device's transmission is being transmitted on one link, the multilink device may prevent the multilink device from transmitting on other links. Specifically, the multilink device may determine the end time of transmission on multiple links based on whether the frame transmitted by the multilink device requests an ACK. The multilink device may simultaneously terminate transmission on multiple links based on whether the frame transmitted by the multilink device requests an ACK. That is, the multilink device may simultaneously terminate transmission on multiple links based on whether the frame included in at least one of the multiple PPDUs requests an ACK. Whether a frame requests an ACK may be determined by an ACK policy. For example, if the ACK policy of a frame is "No Ack," the multilink device may determine that the frame does not request an ACK. Also, if the frame type and subtype are "Action No Ack Frame," the multilink device may determine that the frame does not request an ACK. The ACK policy, frame type, and subtype may be indicated in the MAC header of the frame. Also, as in the embodiment of FIG. 11, the frame requesting an ACK may be a data frame. Specifically, the frame requesting ACK may be a QoS data frame, since information indicating an ACK policy may be included in the QoS data frame.

[0120] In the embodiment of Figure 11, when a multilink device transmits on one link, it cannot receive on the other links. The first station (STA1) and the second station (STA2) of the multilink device transmit first data (Data1) and second data (Data2), respectively. The first station (STA1) and the second station (STA2) simultaneously complete the transmission of the first data (Data1) and the transmission of the second data (Data2). Therefore, the response to the first data (Ack for Data1) and the response to the second data (Ack for Data2) are simultaneously transmitted without internal leakage, and the multilink device can simultaneously receive the response to the first data (Ack for Data1) and the response to the second data (Ack for Data2).

[0121] FIG. 12 shows an operation of the multilink device according to the embodiment of the present invention, in which the multilink device finishes transmission on one of the links first when the multilink device transmits on a plurality of links.

[0122] When a multilink device starts transmission on one link while transmitting on another link, or when it starts transmission on multiple links simultaneously, the multilink device may not be allowed to end transmission on the other links later than transmission on any one link. Therefore, the multilink device can end transmission on the other links before or simultaneously with transmission on any one link. Specifically, when a multilink device starts transmission on another link while transmitting on one link and a response frame to a frame transmitted on the other link is not expected, the multilink device can end transmission on the other link before or simultaneously with transmission on any one link. In this case, the response frame may be an immediate response frame. An immediate response frame may refer to a case where the interval between frames is within a predetermined time interval. In this case, the predetermined time interval may be SIFS. Furthermore, a case where a response frame is not expected may include a case where an ACK is not requested, as described with reference to FIG. 11. Specifically, a frame requesting an immediate response frame may include a frame requesting an ACK. Furthermore, the frame requesting an immediate response may include a frame that triggers uplink transmission. Furthermore, the frame requesting an immediate response may include a QoS data frame requesting an immediate response. Furthermore, the frame requesting an immediate response may include a control frame requesting an immediate response. Furthermore, the frame requesting an immediate response may include a management frame requesting an immediate response. Furthermore, when a PPDU includes a frame requesting an immediate response, it may mean that at least one of the frames included in the PPDU requests an immediate response. When a PPDU includes a frame requesting an immediate response from a station, it may mean that at least one of the frames included in the PPDU requests an immediate response from a station.When a multilink device performs transmission on one link where a response frame is not expected, the multilink device may be allowed not to end transmission on the other link before ending transmission on the other link. Therefore, when a multilink device performs transmission on one link where a response frame is not expected, the multilink device may end transmission on the other link after ending transmission on the one link. When a multilink device performs transmission on one link where a response frame is not expected and a frame transmitted on the other link requests a response frame, the multilink device may be allowed not to end transmission on the other link before ending transmission on the one link. In this case, the response frame may be an immediate response frame. Therefore, when the multilink device transmits only multiple PPDUs that do not include a frame requesting a response, or when it simultaneously transmits one PPDU including a frame requesting a response and a PPDU requesting a response, the multilink device does not need to simultaneously end transmission of the multiple PPDUs. In this case, the multi-link device can transmit multiple PPDUs so that the end of transmission of a PPDU containing only frames that do not request a response is not later than the end of transmission of a PPDU containing a frame that requests a response.

[0123] In the embodiment of Figure 12, a multi-link device cannot receive on any other link while transmitting on one link. A first station (STA1) and a second station (STA2) of the multi-link device transmit first data (Data1) and second data (Data2), respectively. While the first station (STA1) transmits the first data (Data1) to the first AP (AP1), the second station (STA2) begins transmitting the second data (Data2). The second data (Data2) does not require an ACK. The second station (STA2) finishes transmitting the second data (Data2) before the first station (STA1) finishes transmitting it. Therefore, the transmission of the second station (STA2) does not prevent the first station (STA1) from receiving an ACK (Ack for Data1) for the first data.

[0124] The above-described embodiment may also be applied when a multi-link device is unable to receive on one link while transmitting on another link.

[0125] FIG. 13 shows that when a multi-link device according to an embodiment of the present invention transmits on one link, the multi-link device postpones transmission on the other links.

[0126] A multilink device may not be able to transmit simultaneously through multiple links. Specifically, the multilink device can transmit through only one of the multiple links. For example, when the multilink device is transmitting through one link and unable to receive through the other links, the multilink device can transmit through only one of the multiple links. In these embodiments, the multilink device can postpone transmission during channel access. Channel access as described herein may refer to channel access including the backoff procedure previously described with reference to FIG. 6. Specifically, the multilink device can postpone transmission through the remaining links except for the one link through which transmission is performed. For example, the multilink device can perform a backoff procedure on multiple links. In this case, the multilink device can transmit through the link whose backoff counter reaches 0 first and reset the backoff counters on the remaining links. Furthermore, when the backoff counters of the multiple links reach 0, the multilink device can transmit through one of the multiple links. In this case, the multilink device can randomly select one of the multiple links and transmit through the selected link. Furthermore, the multilink device can reset the backoff counters of the non-selected links. The reset may represent the multilink device setting the backoff counter to a value randomly selected within the CW. The multilink device may also reset the CW of a link that did not transmit. Specifically, the multilink device may set the CW of a link that did not transmit to CWmin, which is the minimum value of the CW. These embodiments may be applied when the multilink device transmits on one link and cannot receive on the other links.

[0127] In yet another specific embodiment, the multilink device can determine how to perform channel access on multiple links depending on whether the multilink device is capable of transmitting on one link and receiving on the other links. Specifically, if the multilink device is capable of transmitting on one link and receiving on the other links, the multilink device does not need to perform independent channel access on multiple links. If the multilink device is capable of transmitting on one link and receiving on the other links, the multilink device may perform independent channel access on multiple links.

[0128] As shown in Figures 11 and 12, the multilink device can adjust the length of the PPDU to comply with constraints imposed by concurrency conditions. If it is difficult for the multilink device to adjust the length of the PPDU until the transmission time, the multilink device can transmit only through one of the multiple links. Furthermore, if the transmission time allowed for one link is shorter than the traffic to be transmitted through that link, the multilink device can postpone transmission through that link. For example, in accordance with the embodiments of Figures 11 and 12, the transmission time allowed for a link may be shorter than the traffic to be transmitted through that link.

[0129] In the example of Figure 13, the multilink device performs channel access including backoff independently for the first link (Link1) and the second link (Link2). The backoff counters for the first link (Link1) and the second link (Link2) simultaneously reach 0. At this time, the multilink device transmits only on the second link (Link2) and resets the backoff counter for the first link (Link1).

[0130] In the above-described embodiment, when the multilink device postpones transmission, the multilink device resets the backoff counter. In another specific embodiment, when the multilink device postpones transmission, the multilink device may maintain the value of the backoff counter. This ensures transmission balance between links that may be degraded by transmission postponement.

[0131] FIG. 14 shows an operation of the multilink device according to the embodiment of the present invention, in which the multilink device finishes transmission on one of the links first when the multilink device transmits on a plurality of links.

[0132] As in the embodiment described with reference to FIG. 11 , when a multilink device transmits through multiple links, the multilink device can simultaneously end transmission through the multiple links. Specifically, the multilink device can simultaneously end transmission of PPDUs through the multiple links. Ending transmission of multiple PPDUs simultaneously can be referred to as aligning the ends of the PPDUs. Furthermore, the ends of the multiple PPDUs can be said to be aligned when the difference between the transmission end times of the multiple PPDUs is smaller than, or smaller than or equal to, a threshold value. In this case, the threshold value may be a predetermined value. Specifically, the threshold value may be a value set based on the SIFS. Furthermore, the threshold value may be a value set based on the length of the SIFS and the signal extension. For example, the threshold value may be a value obtained by dividing the sum of the SIFS and the length of the signal extension by 2. In this case, the threshold value may be 8 us.

[0133] When a multilink device transmits multiple PPDUs to another multilink device through multiple links, the multilink device can align the ends of the multiple PPDUs. When a multilink device transmits multiple PPDUs to another multilink device through multiple links, the multilink device can align the ends of two or more PPDUs. In this case, the multilink device can be a sender multilink device, and the other multilink device can be a receiver multilink device. The sender multilink device or the receiver multilink device can be a multilink device that does not support STR or that supports STR only in a limited manner. A multilink device that does not support STR or that supports STR only in a limited manner can be called a non-STR multilink device. A multilink device that supports STR can be called an STR multilink device.

[0134] The receiver multilink device may be a non-STR multilink device. When a sender multilink device transmits multiple PPDUs to a non-STR multilink device over multiple links, the sender multilink device can align the ends of the multiple PPDUs. The non-AP multilink device may be a non-STR multilink device. Therefore, when an AP multilink device transmits multiple PPDUs to a non-STR non-AP multilink device over multiple links, the AP multilink device can align the ends of the multiple PPDUs.

[0135] The sender multilink device may be a non-STR multilink device. When the non-STR multilink device transmits multiple PPDUs to a receiver multilink device over multiple links, the sender multilink device can align the ends of the multiple PPDUs. When the non-STR non-AP multilink device transmits multiple PPDUs to an AP multilink device over multiple links, the non-STR non-AP multilink device can align the ends of the PPDUs.

[0136] In these embodiments, the transmission direction from the AP or AP multilink device to the non-AP STA or non-AP multilink device can be referred to as the downlink (DL). The transmission direction from the non-AP STA or non-AP multilink device to the AP or AP multilink device can be referred to as the uplink (UL). The frames and PPDUs transmitted from the AP or AP multilink device to the non-AP STA or non-AP multilink device can be referred to as DL frames and DL PPDUs, respectively. The frames and PPDUs transmitted from the non-AP STA or non-AP multilink device to the AP or AP multilink device can be referred to as UL frames and UL PPDUs, respectively.

[0137] The above-described embodiment of aligning the ends of the multiple PPDUs may be applied only when at least one of the multiple PPDUs includes a frame requesting an immediate response.

[0138] In the above-described embodiment, multiple PPDUs may be transmitted to one multilink device via multiple links. Specifically, a receiver multilink device may receive multiple PPDUs from multiple stations belonging to the same multilink device via multiple links. For example, the receiver multilink device may operate via a first link and a second link. A first station of the receiver multilink device operates via the first link, and a second station of the receiver multilink device operates via the second link. If a first PPDU is transmitted to the first station via the first link while a second PPDU is transmitted to the second station via the second link, and if each of the first PPDU and the second PPDU includes a frame requesting an immediate response, the end of the first PPDU and the end of the second PPDU may be aligned.

[0139] In the above-described embodiments, transmission of multiple PPDUs over multiple links may refer to simultaneous transmission of multiple PPDUs. Furthermore, transmission of multiple PPDUs over multiple links may refer to simultaneous transmission at any time. Simultaneous transmission of multiple PPDUs may refer to simultaneous transmission at a time point even if the transmission start times of the multiple PPDUs are not the same. Simultaneous transmission of multiple PPDUs may refer to simultaneous transmission at a time point even if the transmission end times of the multiple PPDUs are not the same.

[0140] In yet another specific embodiment, when at least one of the PPDUs transmitted over the multiple links includes a high-priority frame, the multi-link device may not align the ends of the multiple PPDUs. In this case, the high-priority frame may be a frame having a higher priority than a pre-specified priority. Alternatively, the high-priority frame may be a pre-specified frame. This allows the multi-link device to improve the transmission efficiency of high-priority frames.

[0141] In the above-described embodiments, if only some of the PPDUs satisfy a predetermined condition, the multilink device may align only the ends of the PPDUs that satisfy the predetermined condition. When the multilink device transmits multiple PPDUs, the multilink device may align the ends of multiple PPDUs that include frames requesting an immediate response among the multiple PPDUs. For example, if only two of the multiple PPDUs include frames requesting an immediate response, the multilink device may align only the ends of the two PPDUs that include frames requesting an immediate response among the multiple PPDUs. In these embodiments, the multilink device does not need to align the ends of PPDUs that do not include frames requesting an immediate response with the ends of multiple PPDUs that include frames requesting an immediate response. Specifically, the multilink device may transmit PPDUs that do not include frames requesting an immediate response so that the ends of the PPDUs that do not include frames requesting an immediate response are not later than the ends of the PPDUs that include frames requesting an immediate response.

[0142] In the embodiment of FIG. 14, the AP multilink device includes a first AP (AP1), a second AP (AP2), and a third AP (AP3). The non-AP multilink device includes a first station (STA1), a second station (STA2), and a third station (STA3). The AP multilink device or the non-AP multilink device may be a non-STR multilink device. Specifically, the non-AP multilink device may be a non-STR multilink device. The first AP (AP1), the second AP (AP2), and the third AP (AP3) can transmit a first PPDU (PPDU1), a second PPDU (PPDU2), and a third PPDU (PPDU3) to the first station (STA1), the second station (STA2), and the third station (STA3), respectively, using a first link (Link1), a second link (Link2), and a third link (Link3). The first PPDU (PPDU1) includes first data (Data1) requesting an immediate response, and the second PPDU (PPDU2) includes second data (Data2) requesting an immediate response. The third PPDU (PPDU3) includes only third data (Data3) that does not request an immediate response. The AP multilink device aligns the end of the first PPDU (PPDU1) with the end of the second PPDU (PPDU2), but does not need to align the end of the third PPDU (PPDU3) with the end of the first PPDU (PPDU1) and the end of the second PPDU (PPDU2). In this case, the end point of the third PPDU (PPDU3) may be the same as or earlier than the end points of the first PPDU (PPDU1) and the second PPDU (PPDU2).

[0143] FIG. 15 shows an operation of a multilink device according to yet another embodiment of the present invention, in which the multilink device finishes transmission on one of the links first when the multilink device transmits on a plurality of links.

[0144] When a sender multilink device transmits multiple PPDUs to a receiver multilink device via multiple links, the sender multilink device can determine the transmission length of each of the multiple PPDUs depending on whether each of the multiple PPDUs includes a frame requesting an immediate response. Specifically, the sender multilink device can determine that the end of transmission of a PPDU that does not include a frame requesting an immediate response should be the same as or earlier than the end of transmission of a PPDU that includes a frame requesting an immediate response. Therefore, the sender multilink device can determine that the end of transmission of a PPDU that includes a frame requesting an immediate response should be the same as or later than the end of transmission of a PPDU that does not include a frame requesting an immediate response. In such an embodiment, the sender multilink device or the receiver multilink device may be a non-STR multilink device.

[0145] In the embodiment of FIG. 15, the AP multilink device includes a first AP (AP1) and a second AP (AP2). The non-AP multilink device includes a first station (STA1) and a second station (STA2). The AP multilink device or the non-AP multilink device may be a non-STR multilink device. Specifically, the non-AP multilink device may be a non-STR multilink device. The first AP (AP1) and the second AP (AP2) may transmit a first PPDU (PPDU1) and a second PPDU (PPDU2) to the first station (STA1) and the second station (STA2), respectively, using a first link (Link1) and a second link (Link2). The first PPDU (PPDU1) includes first data (Data1) requesting an immediate response, and the second PPDU (PPDU2) includes only second data (Data2) not requesting an immediate response. In this case, the second data (Data2) may be an A-MPDU including only MPDUs that do not require an immediate response. The recipient of the first data (Data1) may be the first station (STA1), and the recipient of the second data (Data2) may be the second station (STA1). The first PPDU (PPDU1) and the second PPDU (PPDU2) may be either an SU PPDU or an MU PPDU. The AP multilink device may transmit the first PPDU (PPDU1) and the second PPDU (PPDU2) so that the transmission end time of the second PPDU (PPDU2) is the same as or earlier than the transmission end time of the first PPDU (PPDU1). The embodiment described with reference to FIG. 15 may be applied regardless of the start time of PPDU transmission. Specifically, as shown in FIG. 15(a), the transmission start time of the first PPDU (PPDU1) may be earlier than the transmission start time of the second PPDU (PPDU2). Also, as shown in FIG. 15(b), the start of transmission of the first PPDU (PPDU1) may be later than the start of transmission of the second PPDU (PPDU2).

[0146] Based on Figures 10 to 15, the embodiments can be used to solve problems that may arise due to internal leakage.

[0147] Mapping between links and TIDs may be set as in the embodiment described with reference to Fig. 9. A specific operation method of the multi-link device at this time will be described with reference to Figs.

[0148] FIG. 16 shows how a multilink device according to an embodiment of the present invention operates using a mapping between links and TIDs.

[0149] In an embodiment of the present invention, even if a mapping between TIDs and links exists, a multi-link device can transmit traffic without following the mapping between TIDs and links. Specifically, an MPDU corresponding to a TID that is not mapped to any one link may be transmitted through that link. For example, an A-MPDU (aggregate-MPDU) transmitted through any one link may be an aggregate of MPDUs corresponding to TIDs mapped to that link and MPDUs corresponding to TIDs not mapped to that link. Furthermore, a PPDU transmitted through any one link may include MPDUs corresponding to TIDs mapped to that link and MPDUs corresponding to TIDs not mapped to that link. Thus, exceptions to the mapping between TIDs and links include:

[0150] Specifically, if a restriction is applied to the transmission end point of one link, a frame corresponding to a TID not mapped to that link may be transmitted over that link. In a specific embodiment, when a multilink device performs transmission, the multilink device may set the transmission end point of the second link based on the transmission end point of the first link. In this case, the multilink device may transmit both an MPDU corresponding to a TID mapped to the second link and an MPDU corresponding to a TID not mapped to the second link. Furthermore, the multilink device may compare the value of the TID not mapped to the link with the value of the TID mapped to the link, and based on the comparison result, determine whether to transmit both an MPDU corresponding to a TID mapped to the second link and an MPDU corresponding to a TID not mapped to the second link. For example, if the value of the TID not mapped to the link is greater than the value of the TID mapped to the link, the multilink device may transmit both an MPDU corresponding to a TID mapped to the link and an MPDU corresponding to a TID not mapped to the second link. In yet another specific embodiment, when the value of a TID not mapped to a link is smaller than the value of a TID mapped to a link, the multi-link device can transmit both an MPDU corresponding to the TID mapped to the link and an MPDU corresponding to the TID not mapped to the second link.

[0151] In yet another specific embodiment, the multi-link device may compare a priority corresponding to a TID not mapped to a link with a priority corresponding to a TID mapped to a link, and determine whether to transmit MPDUs corresponding to the TID mapped to a link and MPDUs corresponding to the TID not mapped to a link together on the link based on the comparison result. In this case, the priority may be a traffic class (TC) or an access category (AC).

[0152] The AP multilink device includes a first AP (AP1) and a second AP (AP2). The non-AP multilink device includes a first station (STA1) and a second station (STA2). A first TID (TID0) and a third TID (TID2) are mapped to a first link (Link1), and a second TID (TID1) is mapped to a second link (Link2). The non-AP multilink device transmits an MPDU corresponding to a third TID (TID2) that is not mapped to the second link (Link2) via the second link (Link2). Specifically, the non-AP multilink device transmits a PPDU corresponding to a first TID (TID0) that is mapped to the second link (Link2) and a third TID (TID2) that is not mapped to the second link (Link2) via the second link (Link2). In this case, the non-AP multilink device satisfies a predetermined condition and transmits an MPDU corresponding to a third TID (TID2) that is not mapped to the second link (Link2) through the second link (Link2). Specifically, because the value of the third TID (TID2) is greater than the value of the second TID (TID1), the non-AP multilink device can transmit an MPDU corresponding to a third TID (TID2) that is not mapped to the second link (Link2) through the second link (Link2). Also, when the non-AP multilink device aligns the end of transmission on the first link with the end of transmission on the second link, there is insufficient traffic to be transmitted on the second link (Link2), so the non-AP multilink device can transmit an MPDU corresponding to a third TID (TID2) that is not mapped to the second link (Link2) through the second link (Link2).

[0153] When a multilink device selects a link to be used for transmission from among multiple links, the multilink device can transmit frames corresponding to TIDs that are not mapped to the selected link via the selected link. Specifically, when a multilink device selects a link to be used for transmission from among multiple links, the multilink device can transmit frames corresponding to TIDs that are mapped to links that are not selected from among the multiple links via the selected link. Specifically, such an embodiment may be applied to the embodiment described using FIG. 13.

[0154] In these embodiments, a problem may arise as to which link the multilink device should use to transmit a response to a frame corresponding to a TID not mapped to a link. The multilink device may transmit a response to the frame corresponding to the TID not mapped to a link via the link on which the frame was transmitted. In this case, the response to the frame may be an ACK. For example, in the embodiment of FIG. 16, the AP multilink device may transmit an ACK for a frame corresponding to the first TID (TID0) via the first link (Link1) and an ACK for a frame corresponding to the third TID (TID2) transmitted via the first link (Link1). Furthermore, the AP multilink device may transmit an ACK for a frame corresponding to the second TID (TID1) via the second link (Link2) and an ACK for a frame corresponding to the third TID (TID2) transmitted via the second link (Link2). In these embodiments, the multilink device transmits a response to the frame via the link on which the frame was received, thereby reducing implementation complexity.

[0155] In still another specific embodiment, the multilink device may transmit a response to a frame corresponding to a TID not mapped to a link but via a link mapped to the TID. In this case, the response to the frame may be an ACK. For example, in the embodiment of FIG. 16, the AP multilink device may transmit an ACK for a frame corresponding to a first TID (TID0) and an ACK for a frame corresponding to a third TID (TID2) via the first link (Link1). The AP multilink device may also transmit an ACK for a frame corresponding to a second TID (TID1) via the second link (Link2). In these embodiments, the multilink device transmits a response to a frame corresponding to a TID via a link not mapped to the TID, thereby reducing the processing burden of having to combine responses transmitted via multiple links.

[0156] Exceptional situations that can be transmitted regardless of the mapping between links and TIDs have been described with reference to Figure 16. Exceptional situations that can be transmitted regardless of the mapping between links and TIDs will be described again with reference to Figures 17 and 18 according to still another specific embodiment.

[0157] 17 illustrates an operation of a station transmitting an uplink multiple access point (MU) according to an embodiment of the present invention, and FIG. 18 illustrates an operation of a multi-link device collecting multi-TIDs according to an embodiment of the present invention.

[0158] As described above, when a restriction is applied to the transmission end time, the multilink device can compare the priority corresponding to the TID not mapped to the link with the priority corresponding to the TID mapped to the link. Based on the comparison result, the multilink device can determine whether to transmit the MPDU corresponding to the TID not mapped to the link over the link. Specifically, if the priority of the MPDU corresponding to the TID not mapped to the link is higher than the priority of the MPDU corresponding to the TID mapped to the link, the multilink device can transmit the MPDU corresponding to the TID not mapped to the link over the link. For example, if the priority of the MPDU corresponding to the TID not mapped to the link has the highest priority, the multilink device can transmit the MPDU corresponding to the TID not mapped to the link over the link.

[0159] In yet another specific embodiment, if the priority of an MPDU corresponding to a TID not mapped to a link is lower than the priority of an MPDU corresponding to a TID mapped to a link, the multilink device can transmit the MPDU corresponding to the TID not mapped to a link over the link. For example, if the priority of an MPDU corresponding to a TID not mapped to a link has the lowest priority, the multilink device can transmit the MPDU corresponding to the TID not mapped to a link over the link. This allows the multilink device to have an opportunity to transmit traffic that is difficult to transmit due to its low priority.

[0160] A multilink device may transmit an MPDU corresponding to a TID not mapped to a link via the link only if an MPDU corresponding to a TID mapped to the link and an MPDU corresponding to a TID not mapped to the link are transmitted together. Specifically, transmitting an MPDU corresponding to a TID mapped to a link and an MPDU corresponding to a TID not mapped to the link together may be transmitted as follows: An A-MPDU (aggregate-MPDU) transmitted via any one link may be an aggregation of an MPDU corresponding to a TID mapped to the link and an MPDU corresponding to a TID not mapped to the link. Furthermore, a PPDU transmitted via any one link may include an MPDU corresponding to a TID mapped to the link and an MPDU corresponding to a TID not mapped to the link.

[0161] These embodiments may be applied to UL MU transmission operations. First, UL MU transmission operations will be described with reference to FIG.

[0162] Multiple stations may transmit PPDUs simultaneously. Such transmission or a series of processes for transmission is called an uplink (UL) multi-user (MU) operation or UL MU transmission. UL MU transmission may be preceded by an operation that triggers transmission of multiple stations.

[0163] Furthermore, when multiple stations transmit one PPDU simultaneously, the multiple stations can use a TB (trigger-based) PPDU. The TB PPDU can include the above-mentioned HE TB PPDU and EHT TB PPDU. The TB PPDU can also represent a PPDU that supports simultaneous transmission by multiple stations. Multiple stations receive a frame that triggers UL MU transmission, and the multiple stations can transmit UL MUs based on the received frame. The AP can transmit a frame that triggers UL MU transmission to multiple stations. The frame that triggers UL MU transmission can also indicate the resource units (RUs) allocated to each of the multiple stations in the UL MU transmission where the UL MU transmission is performed. The station can transmit the TB PPDU in the RU allocated to the station. The frame that triggers UL MU transmission can be a trigger frame or a frame containing trigger information. A frame containing trigger information can include the trigger information in the MAC header. Specifically, a frame containing trigger information can include the trigger information in the A-Control field. Specifically, the trigger information may be a triggered response scheduling (TRS) control field. Furthermore, the UL MU transmission may be transmitted in the aforementioned TB PPDU. Furthermore, multiple stations may transmit UL MUs in immediate response. That is, the interval between the PPDU containing the frame that triggers the UL MU transmission and the PPDU containing the UL MU transmission may be SIFS.

[0164] The frame that triggers the UL MU transmission may include information regarding the length of the PPDU including the UL MU transmission. For convenience of explanation, the information regarding the length of the PPDU including the UL MU transmission is referred to as response length information. The response length information may indicate the length of the PPDU including the UL MU transmission. A station may determine the length of the PPDU including the UL MU transmission based on the response length information included in the frame that triggers the UL MU transmission. Specifically, the response length information may indicate the value of the Length field in the L-SIG field of the PPDU including the UL MU transmission. For example, a station may determine the value of the Length field in the L-SIG field of the TB PPDU based on the length field of the trigger frame. Also, even if the station does not have enough traffic to generate a PPDU with response length information, the station may determine the length of the TB PPDU based on the response length information. Specifically, a station may insert padding into the TB PPDU. For example, if there are still empty bits in the TB PPDU after the station has inserted all of the traffic in its buffer into the TB PPDU, the station may insert padding into the empty bits. This allows the station to satisfy the length of the TB PPDU indicated by the response length information. Furthermore, the response length information may indicate the number of OFDM symbols included in the TB PPDU. Therefore, when a station transmits a UL MU, the station transmits according to the length indicated by the frame that triggers the UL MU transmission. Furthermore, all stations transmitting a UL MU can transmit TB PPDUs of the same length. Furthermore, a response to a UL MU transmission may be an immediate response to the UL MU transmission. Therefore, the interval between a UL MU transmission and a response to the UL MU transmission may be SIFS.

[0165] Referring to FIG. 17, the AP transmits a trigger frame to a first station (STA1) and a second station (STA2). The first station (STA1) and the second station (STA2) each transmit a TB PPDU in the RU indicated by the trigger frame as being assigned to the first station (STA1) and the second station (STA2), respectively. The length of the TB PPDU transmitted by the first station (STA1) and the second station (STA2) is determined by the response length information indicated by the trigger frame. The lengths of the TB PPDUs transmitted by the first station (STA1) and the second station (STA2) are the same. In addition, the first station (STA1) and the second station (STA2) transmit a TB PPDU as an immediate response to the trigger frame. The AP transmits an ACK for the frame included in the TB PPDU transmitted by the first station (STA1) and the second station (STA2). In this way, restrictions on the transmission end time may also be applied when a station transmits a TB PPDU. In this case, an embodiment regarding exceptions to the mapping between links and TIDs may be applied, which will be described in detail with reference to FIG.

[0166] When a station transmits an UL MU, the station may transmit a frame corresponding to a TID that is not mapped to the link on which the UL MU is transmitted. Specifically, when a station transmits an UL MU, the station may transmit both a frame mapped to the link on which the UL MU is transmitted and a frame corresponding to a TID that is not mapped to the link. In FIG. 18, a station transmits a TB PPDU through a first link (Link 1). In this case, the uplink of the first link (Link 1) is mapped to AC_VI and AC_BE. In this case, the station may transmit a TB PPDU including padding and a data frame or PDSU corresponding to AC_VI and AC_BE, as shown in FIG. 18(b). However, in this embodiment, if the length of the padding is excessively long, transmission efficiency may be reduced. In addition, a station transmitting a trigger frame, for example, an AP, may not accurately know the traffic stored in the buffers of multiple stations transmitting UL MUs, and therefore the length of the padding included in the TB PPDU may be large. Therefore, the station can further include data frames or PSDUs corresponding to other ACs not mapped to the first link (Link1), ie, AC_VO, in the TB PPDU, as shown in FIG. 18(c).

[0167] As described above, a station can compare the priority of a TID mapped to a link with the priority of a TID not mapped to a link, and based on the comparison result, determine whether to transmit a frame corresponding to a TID not mapped to a link on that link. For example, in FIG. 18(c), AC_VO can have a higher priority than AC_VI or AC_BE, which are ACs mapped to the first link (Link1). Also, as described above, a station cannot transmit a PPDU containing only frames corresponding to TIDs not mapped to a link, but can transmit both frames corresponding to TIDs mapped to a link and frames corresponding to TIDs not mapped to a link. Although FIG. 18 illustrates an embodiment of the present invention using an AC, as described above, these embodiments may also be applied when a link is mapped to a TID or TSID instead of an AC.

[0168] Furthermore, the above-described embodiment may be applied together with a multi-TID aggregation rule. The multi-TID aggregation rule defines a rule for aggregating MPDUs corresponding to different TIDs into one A-MPDU. Therefore, MPDUs aggregated according to the multi-TID aggregation rule do not need to follow the link-TID mapping. Specifically, when a station aggregates MPDUs according to the multi-TID aggregation rule, it can transmit MPDUs corresponding to TIDs that are not mapped to a link over that link. The multi-TID aggregation rule may be as follows:

[0169] 1) The TXOP limit of the transmission sequence in which multi-TID aggregation is performed is 0 or greater.

[0170] 2) At least one frame or MPDU of the AC used to acquire the primary AC or TXOP is included in the aggregated A-MPDU.

[0171] 3) The TID corresponding to the frames or MPDUs aggregated into the A-MPDU is the primary AC or a TID with a higher priority than the primary AC.

[0172] 4) The length of the A-MPDU does not exceed the acquired TXOP of the main AC.

[0173] 5) The number of TIDs of frames or MPDUs aggregated into an A-MPDU does not exceed the number of TIDs indicated by Multi-TID Aggregation Rx Support.

[0174] In yet another specific embodiment, condition 3) of the multi-TID aggregation rule described above may be replaced with the following condition 3-1).

[0175] 3) The TID corresponding to the frames or MPDUs aggregated into the A-MPDU is the primary AC or a TID with a lower priority than the primary AC.

[0176] In yet another specific embodiment, a station can transmit a TID that is not mapped to a link on the link based on the PPDU format. Specifically, when a station transmits a DL MU PPDU, the station can transmit a frame corresponding to a TID that is not mapped to a link on the link. In this case, the DL MU PPDU may be a DL HE MU PPDU or an EHT PPDU transmitted to multiple users. In addition, the station can transmit a frame corresponding to any TID that is not mapped to a link on the link.

[0177] Specifically, when a station transmits a TB PPDU, the station can transmit frames corresponding to TIDs not mapped to a link on the link. In this case, the TB PPDU may be an HE TB PPDU or an EHT TB PPDU. In a specific embodiment, if the Preferred AC subfield of a trigger frame indicates a specific AC and a TID not mapped to a link has a priority equal to or higher than the priority of the specific AC, the station can transmit frames corresponding to the TID using the TB PPDU. In yet another specific embodiment, if the Preferred AC subfield of a trigger frame indicates a specific AC and a TID not mapped to a link has a priority lower than the priority of the specific AC, the station can transmit frames corresponding to the TID using the TB PPDU. This embodiment may be applied when there are no frames in the transmission buffer that have a priority higher than the priority of the specific AC. Also, as described above, within the allowable length of the TB PPDU, the station can transmit frames corresponding to a TID not mapped to a link using the TB PPDU. In this case, the number of TIDs of frames aggregated into an A-MPDU may be limited. Specifically, a TID Aggregation Limit subfield included in the trigger frame may indicate the maximum number of TIDs aggregated into an A-MPDU.

[0178] FIG. 19 illustrates elements that signal information regarding link-to-TID mapping according to an embodiment of the present invention.

[0179] A station may signal whether it supports or allows the embodiments described with reference to FIGS. 16 to 18. This is because receiving a frame corresponding to a TID other than the TID mapped to the link may require the station to perform additional operations. Specifically, when a constraint on the transmission end time is applied, the station may signal whether it supports or allows frame transmission that does not follow the link-TID mapping. If the information indicating whether it supports or allows frame transmission that does not follow the link-TID mapping indicates a first preset value, the information may indicate that the station supports or allows frame transmission that does not follow the link-TID mapping. Specifically, if the information indicating whether it supports or allows frame transmission that does not follow the link-TID mapping indicates a first preset value, the information may indicate that the station supports or allows frame transmission that does not follow the link-TID mapping when a constraint on the transmission end time is applied.

[0180] When the information indicating whether frame transmission that does not conform to the link-TID mapping is supported or tolerated indicates a second preset value, the information may indicate that the station does not support or tolerate frame transmission that does not conform to the link-TID mapping. Specifically, when the information indicating whether frame transmission that does not conform to the link-TID mapping is supported or tolerated indicates a second preset value, the information may indicate that the station does not support or tolerate frame transmission that does not conform to the link-TID mapping when a constraint on the transmission end time is applied.

[0181] Furthermore, the information indicating whether frame transmission that does not comply with the link-TID mapping is supported or permitted may indicate whether a station supports or permits transmission according to a restriction on the transmission end time, where permitting may indicate whether the station can receive the transmission.

[0182] In addition, a station may signal the maximum number of TIDs that the station can aggregate in one A-MPDU. In this case, the maximum number of TIDs that the station can aggregate in one A-MPDU may be equal to or greater than the maximum number indicated by the TID aggregation limit field of the trigger frame. Specifically, a station may signal the maximum number of TIDs that the station can aggregate in addition to the TIDs mapped to the link. In yet another specific embodiment, a station may signal the maximum number of TIDs that the station can aggregate, including the TIDs mapped to the link. In the above embodiment, the signaling may indicate the maximum number of TIDs that the station can aggregate when a restriction on the transmission end point is applied. In addition, a station may signal the maximum number of TIDs that the station can receive.

[0183] In the above-described embodiment, a Capabilities element or an Operation element may be used for signaling. A station may use the Capabilities element or the Operation element to signal whether it supports or allows frame transmission that does not follow the link-to-TID mapping. A station may also use the Capabilities element or the Operation element to signal the maximum number of TIDs that the station can aggregate. The Capabilities element may include an EHT Capabilities element. The Operation element may include an EHT Operation element.

[0184] 19(a) shows a Capabilities element according to one embodiment of the present invention, and FIG. 19(b) shows an Operation element according to yet another embodiment of the present invention. The Multi-link multi-TID aggregation support subfield of the Capabilities element allows a non-AP station to signal to an AP whether the station supports frame transmission that does not follow the link-to-TID mapping. The Number of TIDs subfield of the Capabilities element indicates the maximum number of TIDs that a station can aggregate. The Permission of Multi-link multi-TID aggregation subfield of the Operation element can indicate whether the AP allows a non-AP station to transmit frames that do not follow the link-to-TID mapping. In addition, the Number of TIDs subfield of the Capabilities element can indicate the maximum number of TIDs that the AP can receive.

[0185] The signaling indicating whether to support frame transmission that does not follow the link-to-TID mapping and the signaling indicating whether to allow frame transmission that does not follow the link-to-TID mapping may be included in the same type of element. Furthermore, the signaling indicating whether to support frame transmission that does not follow the link-to-TID mapping and the signaling indicating whether to allow frame transmission that does not follow the link-to-TID mapping may be included in the same type of subfield of the same type of element. In this case, the information indicated by the subfield of the element may differ depending on the role of the station transmitting the element. Specifically, the information indicated by the subfield of the element may differ depending on whether the element is transmitted by a non-AP station or an AP. For example, when a non-AP station transmits the element, the subfield of the element may indicate whether to support frame transmission that does not follow the link-to-TID mapping. Furthermore, when an AP transmits the element, the subfield of the element may indicate whether to allow frame transmission that does not follow the link-to-TID mapping.

[0186] When a restriction on the transmission end point is applied, whether frame transmission that does not follow the link-TID mapping is permitted may be determined for each PPDU format. When information indicating whether frame transmission that does not follow the link-TID mapping is permitted is included in a frame or PPDU, the information may be applied to a response to the frame or PPDU. When information indicating whether frame transmission that does not follow the link-TID mapping is permitted is included in a frame or PPDU, the information may be applied to a transmit opportunity (TXOP) that includes the frame or PPDU. The maximum number of TIDs that a station can aggregate may be determined for each PPDU format. When information indicating the maximum number of TIDs that a station can aggregate is included in a frame or PPDU, the information may be applied to a response to the frame or PPDU. When information indicating the maximum number of TIDs that a station can aggregate is included in a frame or PPDU, the information may be applied to a response to the frame or PPDU. When information indicating the maximum number of TIDs that a station can aggregate is included in a frame or PPDU, the information may be applied within the TXOP that includes the frame or PPDU.

[0187] Specifically, the frame that triggers the UL MU transmission may include information indicating whether frame transmission that does not follow the link-to-TID mapping is permitted. When a station transmits a response to the frame that triggers the UL MU transmission, the station can determine whether to transmit a frame corresponding to a TID that is not mapped to a link based on the information indicating whether frame transmission that does not follow the link-to-TID mapping is permitted. In a specific embodiment, the information indicating whether frame transmission that does not follow the link-to-TID mapping is permitted may be included in the Common Info field of the trigger frame. For example, the information indicating whether frame transmission that does not follow the link-to-TID mapping is permitted may be included in the 64th bit, B63, of the Common Info field.

[0188] In yet another specific embodiment, the next bit of the Reserved subfield of the UL HE-SIG-A2 may include information indicating whether frame transmission that does not follow the link-TID mapping is permitted. In yet another specific embodiment, the information indicating whether frame transmission that does not follow the link-TID mapping is permitted may be included in the bit before the Trigger Dependent Common Info field. In yet another specific embodiment, the information indicating whether frame transmission that does not follow the link-TID mapping is permitted may be included in the User Info field of the trigger frame. Furthermore, the embodiment applied to the information indicating whether frame transmission that does not follow the link-TID mapping is permitted may also be applied to the information indicating the maximum number of TIDs that a station can aggregate. The aforementioned Common Info field includes information commonly applied to all stations or TB PPDUs responding to the trigger frame. The User Info field includes information applied to the stations responding with the RU indicated by the User Info field or the TB PPDUs to be transmitted.

[0189] FIG. 21 shows a station according to an embodiment of the present invention performing channel access to transmit a trigger frame.

[0190] When a station transmits a frame that triggers a UL MU transmission, the station may perform the channel access described with reference to FIG. 6. In this case, the AIFS may be determined based on the AC, TID, or priority of the traffic that the station intends to transmit. Specifically, the AIFS may be a value obtained by adding the SIFS to the product of the AIFSN and the slot time. When a station intends to transmit traffic with a relatively high priority, the length of the AIFS may be relatively short. On the other hand, when a station intends to transmit traffic with a relatively low priority, the length of the AIFS may be relatively long. When performing channel access to transmit a station trigger frame, how the station determines the AC, TID, or priority to apply can be an issue.

[0191] When a station accesses a channel to transmit a trigger frame, the station may do so based on the AC, TID, or priority corresponding to the frame transmitted in response to the trigger frame and the link-TID mapping. Specifically, when a station accesses a channel to transmit a trigger frame, the station may do so based on the AC corresponding to the frame transmitted in response to the trigger frame and the link-TID mapping. In this case, the link-TID mapping may be established between the sender of the trigger frame and the receiver of the trigger frame. In a specific embodiment, the link-TID mapping may be a link-TID mapping from the receiver of the trigger frame to the sender of the trigger frame. When a station accesses a channel to transmit a trigger frame, the station may apply a defined TID or AC to the link-TID mapping from the receiver of the trigger frame to the sender of the trigger frame. When a station accesses a channel to transmit a trigger frame, the station may not apply an undefined TID or AC to the link-TID mapping from the receiver of the trigger frame to the sender of the trigger frame. When a station accesses a channel to transmit a trigger frame, the station can apply a TID or AC determined based on the defined TID or AC to the mapping of links and TIDs from the receiver of the trigger frame to the sender of the trigger frame. Furthermore, when there are multiple receivers of the trigger frame, the mapping of links and TIDs may be a mapping of links and TIDs from the multiple receivers to the sender. These embodiments may be applied when a PPDU containing a frame that triggers a UL MU transmission contains only a frame that triggers a UL MU transmission. These embodiments may also be applied only when a PPDU containing a frame that triggers a UL MU transmission does not contain a QoS data frame.

[0192] Furthermore, the above-described embodiments may be applied when all recipients of a PPDU containing a frame that triggers an UL MU transmission are multilink devices. Therefore, these above-described embodiments may be applied when all recipients of a PPDU containing a trigger frame are stations included in a multilink device. If the recipients of a PPDU containing a trigger frame include stations that are not included in a multilink device, the stations can use any AC.

[0193] Also, if the frame that triggers the UL MU transmission triggers random access without specifying a station, the station can perform channel access regardless of the mapping between the link and the TID.

[0194] In FIG. 20, the AP multilink device includes a first AP (AP1). Also, a first non-AP multilink device (Non-AP MLD 1) includes a first station (STA1). Also, a second non-AP multilink device (Non-AP MLD 2) includes a second station (STA2). A first link (Link1) is established between the first station (STA1) and the first AP (AP1). A first link (Link1) is established between the second station (STA2) and the first AP (AP1). Mapping between the link and the TID is established in the first link (Link1). AC_VI and AC_VO are mapped to the link from the first station (STA1) to the first AP (AP1). Also, all TIDs are mapped to the link from the first AP (AP1) to the first station (STA1). Mapping between the link and the TID is established in the second link (Link2). AC_VO is mapped to the link from the second station (STA2) to the first AP (AP1). Also, all TIDs are mapped to the link from the second AP (AP2) to the first station (STA1). In FIG. 20(b), when the first AP (AP1) transmits a trigger frame to the first station (STA1) and the second station (STA2), the first AP (AP1) performs channel access based on AC_VI and AC_VO. This is because AC_VI and AC_VO are mapped to the link from the first station (STA1) to the first AP (AP1), and AC_VO is mapped to the link from the second station (STA2) to the first AP (AP1). When the first AP (AP1) transmits a trigger frame to the first station (STA1) and a third station (STA3) that is not included in any multilink device, the first AP (AP1) may perform channel access using any AC. When the first AP (AP1) transmits a trigger frame that triggers random access, the first AP (AP1) may perform channel access using any AC.

[0195] In yet another specific embodiment, when a station performs channel access to transmit a frame that triggers an UL MU transmission, the station can perform channel access regardless of link-TID mapping. In this case, the station may use any AC. In this case, the link-TID mapping may be a link-TID mapping for the UL. Also, the link-TID mapping may be a link-TID mapping for the direction in which the trigger frame is transmitted.

[0196] As described above, when a station transmits a TB PPDU, the station can transmit frames corresponding to TIDs that are not mapped to a link on the link. In this way, when a station does not obtain a TXOP through a contention procedure, the station can transmit regardless of the mapping between links and TIDs. Also, when a station obtains a TXOP through a contention procedure, the station can transmit based on the mapping between links and TIDs. For example, when a station does not obtain a TXOP through a contention procedure, the station can transmit frames corresponding to TIDs that are not mapped to a link on the link. When a station obtains a TXOP through a contention procedure, the station can transmit only frames corresponding to TIDs that are mapped to a link on the link.

[0197] FIG. 21 illustrates the operation of a multi-link device transmitting over multiple links according to an embodiment of the present invention.

[0198] As in the embodiments described with reference to FIGS. 10 to 15, restrictions may be applied to multilink transmissions in relation to the transmission end time. In a specific embodiment, a multilink device may determine whether to apply restrictions related to the transmission end time based on the frequency spacing between links. The degree of internal leakage may vary depending on the frequency spacing. When the frequency spacing between links is within a predetermined frequency spacing, the multilink device may be restricted from simultaneously transmitting and receiving on multiple links. Furthermore, when the frequency spacing between links is greater than the predetermined frequency spacing, the multilink device may not be restricted from simultaneously transmitting or receiving on multiple links.

[0199] Additionally, limitations may be placed on the bandwidth used by STR-limited multilink devices or multilink devices communicating with STR-limited multilink devices, and in certain circumstances, STR-limited multilink devices or multilink devices communicating with STR-limited multilink devices may use less bandwidth than a certain amount.

[0200] In FIG. 21, the non-AP multilink device includes a first station (STA1) and a second station (STA2). The first station (STA1) and the second station (STA2) operate on the first link (Link1) and the second link (Link2), respectively. The non-AP multilink device supports STR in a limited manner. Specifically, the STR of the non-AP multilink device may be limited depending on the channel location or bandwidth of the link. In FIG. 21, when the non-AP multilink device operates on the P20 channel of the first link (Link1) and the channel of the second link, the non-AP multilink device can perform STR. Also, when the non-AP multilink device operates on the S20 or S40 channel of the first link (Link1) and operates on the channel of the second link, the non-AP multilink device cannot perform STR.

[0201] In this way, a station transmitting to a non-AP multilink can transmit a PPDU using a limited bandwidth. Specifically, a station transmitting to a non-AP multilink can transmit a PPDU using a limited bandwidth when a non-AP multilink device transmits. In the embodiment of Figure 21, when a second station (STA2) is transmitting, the first AP (AP1) can transmit to the second station (STA2) using a channel that does not include the S20 channel or the S40 channel, which are limited channels in the first link (Link1).

[0202] The multilink device can independently determine whether to use the restricted channels described above. In another specific embodiment, the use of the restricted channels may be specifically indicated. For example, a frame triggering UL MU transmission may allocate the restricted channels. Furthermore, the multilink device may signal whether STR is possible when the channel is used for each channel. For example, the multilink device may signal whether STR is possible when each of the P20, P40, and P80 channels is used.

[0203] FIG. 22 shows the operation of the multilink device according to the embodiment of the present invention for setting the NAV.

[0204] As described above, internal leakage can occur when transmission and reception are performed simultaneously on multiple adjacent links, resulting in a transmission failure. In FIG. 22, a multilink device transmits on a second link while receiving on a first link. Transmission on the second link can result in a reception failure on the first link. If a station operating on the second link determines that the channel for the second link is idle, the station accesses the channel and transmits. A station operating on the first link (Link 1) sets a network allocation vector (NAV) based on a frame or PPDU transmitted on the first link (Link 1). A station operating on the first link (Link 1) can determine that the channel is busy based on the NAV while another station is transmitting on the first link (Link 1). In this way, if a frame or PPDU transmitted on the first link can set the NAV for the second link, the probability of a transmission failure due to internal leakage can be reduced. This will be described with reference to FIGS. 23 to 26.

[0205] FIG. 23 shows the operation of the multilink device according to the embodiment of the present invention for setting the NAV.

[0206] A multi-link device can share duration information between links. In this case, the duration information may be the TXOP Duration field of the signaling field of the PPDU. In this case, the signaling field may be the HE-SIG-A field. Alternatively, the signaling field may be the U-SIG field. Alternatively, the duration information may be a value indicated by the Duration / ID field of the MAC header. The TXOP Duration field and the Duration / ID field indicate the TXOP. In yet another specific embodiment, the duration information may be a value indicated by the Length field of the L-SIG field of the PPDU. The Length field indicates the length from the end of the L-SIG field to the end of the PPDU in a PPDU including the L-SIG field.

[0207] The multilink device can restrict channel access or transmission on each link based on the shared duration information. Specifically, the multilink device can set the NAV of the station on each link based on the shared duration information. For example, a station included in the multilink device can set its NAV based on a frame or PPDU transmitted to another station included in the same multilink device. In this case, when the multilink device performs channel access or transmission, the multilink device may reset its NAV. In this case, the NAV may be an intra-BSS NAV. The intra-BSS NAV is a NAV set by an intra-BSS frame or intra-BSS PPDU.

[0208] In Figure 23, a multilink device receives data via a first link. The duration information received via the first link is transmitted to a second link, and the station operating via the second link sets its NAV based on the transmitted duration information. Since the NAV is also set for the station operating via the second link, the station operating via the second link does not access or transmit a channel while transmission is in progress via the first link.

[0209] In yet another specific embodiment, multiple stations included in a multilink device can use an inter-link NAV. Specifically, a station included in the multilink device can access a channel based on the inter-link NAV, which is a NAV set based on frames or PPDUs exchanged by other stations included in the same multilink device. For example, if a multilink device operates on a first link and a second link, a station operating on the second link among the stations in the multilink device can set its inter-link NAV based on a PPDU or frame transmitted on the first link. In this case, the station may not transmit on the second link based on the set inter-link NAV value. Specifically, the station may determine that the channel of the second link is busy based on the set inter-link NAV value. In addition, a multilink device that does not support STR can access a channel based on the inter-link NAV. In this case, a multilink device that has set its inter-link NAV can determine whether to perform channel access or transmission on multiple links or all links on which the multilink device operates based on the inter-link NAV.

[0210] In addition, a station can access a channel based on a basic NAV in addition to an intra-BSS NAV. The basic NAV may be a NAV set by an inter-BSS frame or an inter-BSS PPDU. If a station cannot determine whether a received frame is an inter-BSS frame or an intra-BSS frame, or whether a received PPDU is an inter-BSS PPDU or an intra-BSS PPDU, the station can set the basic NAV based on the received frame or PPDU.

[0211] As in the above embodiment, when an inter-link NAV is set, even if the set NAV is reset by a transmission on another link, the NAV value set by the transmission within the link may remain unchanged. For example, if a multilink device operates on a first link and a second link, a station operating on the second link among the stations of the multilink device may set its NAV based on a PPDU or frame transmitted on the second link. After that, if the station sets its NAV based on a PPDU or frame transmitted on the first link and the TXOP expires on the first link and the NAV is reset, it may be reset to the NAV set for transmission on the second link. When the inter-link NAV is operated, the multilink device can maintain the NAV set for transmission on the second link even if the TXOP expires on the first link and the inter-link NAV is reset. Therefore, the inter-link NAV allows the multilink device to operate stably.

[0212] In the above-described embodiment, the operation of the station setting the NAV may be replaced by the operation of the station suspending channel access or suspending transmission at the physical layer. Alternatively, in the above-described embodiment, the operation of the station setting the NAV may be replaced by the operation of the station determining that the channel is busy. In such a case, the operation of the station resetting the NAV may be replaced by the operation of the station accessing the channel, transmitting, or determining that the channel is idle. For this purpose, a primitive exchanged between the physical layer and the MAC layer may be used. Specifically, a primitive that connects the MAC layer of one station in the multilink device with the physical layer of another station in the multilink device may be used. Alternatively, specifically, the MAC layer of one station in the multilink device may be connected with the MAC layer of another station in the multilink device.

[0213] Furthermore, when one station in the multilink device starts receiving a PPDU, the other stations in the multilink device may suspend their channel access. As described above, the other stations may suspend their channel access based on the duration information. However, the suspension of channel access may be delayed depending on the position of the field containing the duration information. Therefore, internal leakage may occur if channel access is performed and transmission continues until the duration information is acquired. Therefore, as described above, when one station in the multilink device starts receiving a PPDU, the other stations in the multilink device may suspend their channel access. Furthermore, if the intended recipient of the PPDU received by one station or the frame contained in the PPDU is not the corresponding station, the other stations may resume the suspended channel access. This will be described in detail with reference to FIG. 24.

[0214] FIG. 24 illustrates a station in a multi-link device according to an embodiment of the present invention resuming channel access or transmission after the station suspends channel access or transmission due to a PPDU received by another station in the multi-link device.

[0215] As described above, a station in a multi-link device can suspend channel access or transmission in response to a PPDU received by another station in the multi-link device. In this case, if the other station does not receive the PPDU or the frame contained in the PPDU, the station can resume channel access or transmission. Specifically, if the other station fails to decode the PPDU, the station can resume channel access or transmission. In a specific embodiment, if the other station obtains duration information from the L-SIG field of the PPDU, the station can continue suspending channel access or transmission. If the station fails to obtain duration information from the L-SIG field of the PPDU, the station can resume channel access or transmission. For example, if the station fails to decode the L-SIG field of the PPDU, the station can resume channel access or transmission. Also, if the other station fails to decode the U-SIG field or the HE-SIG-A field of the PPDU, the station can resume channel access or transmission. In a specific embodiment, if another station obtains the duration information from the U-SIG field or the HE-SIG-A field of the PPDU, the station can continue the channel access or transmission interruption, and if the PHY identifier of the PPDU received by the other station is a PPDU format that the other station does not support, the station can resume the channel access or transmission.

[0216] Also, if the BSS color of the PPDU received by the other station does not indicate the BSS to which the other station belongs, the station can resume channel access or transmission. If the BSS color of the PPDU received by the other station indicates the BSS to which the other station belongs, the station can continue channel access or transmission suspension. If the station cannot obtain the BSS color from the U-SIG field or HE-SIG-A field of the PPDU, the station can resume channel access or transmission.

[0217] Furthermore, if the other station is not the intended recipient of the PPDU received by the other station, the station can resume channel access or transmission. If the other station is the intended recipient of the PPDU received by the other station, the station can continue suspending channel access or transmission. If the other station is the intended recipient of the received PPDU, it may be determined that at least one of the STA-IDs included in the EHT-SIG or HE-SIG-B of the PPDU indicates the other station. Specifically, if the other station is the intended recipient of the received PPDU, it may be determined that one of the STA-IDs included in the EHT-SIG or HE-SIG-B of the PPDU indicates a group including the other station. For example, if one of the STA-IDs is broadcast, the station can determine that the other station is the intended recipient of the received PPDU.

[0218] Furthermore, if the intended recipient of the frame included in the PPDU received by the other station is not the other station, the station can resume channel access or transmission. In this case, if the station indicated by the RA field or DA field of the MAC header is the other station, the station can determine that the intended recipient of the frame included in the PPDU received by the other station is the other station. If the RA field or DA field of the MAC header indicates a group including the other station, the station can determine that the intended recipient of the frame included in the PPDU received by the other station is the other station. If the RA field or DA field of the MAC header is broadcast, the station can determine that the intended recipient of the frame included in the PPDU received by the other station is the other station.

[0219] A station may maintain channel access or transmission suspension if the other station is the intended recipient of the frame contained in the PPDU received by the other station.

[0220] In the above-described embodiment, if a station continues to suspend channel access or transmission, the station can suspend channel access or transmission until the end of the PPDU received by the other station. In such an embodiment, the station can quickly resume transmission. In yet another specific embodiment, if a station continues to suspend channel access or transmission, the station can suspend channel access or transmission until the TXOP duration. In such an embodiment, the station can more stably protect the frame exchange sequence performed on other links. In this case, the TXOP duration can be obtained from the signaling field of the PPDU or the Duration / ID field of the MAC header.

[0221] The above-described channel access or transmission suspension / resume may be applied when another station receives a PPDU and sequentially decodes the signaling fields of the received PPDU. In this case, the decoding order may be determined according to the PPDU format and the frame format. For example, as shown in FIG. 24, if the received PPDU is an EHT PPDU, the other station may sequentially decode the L-SIG, U-SIG, EHT-SIG, and MAC header. Also, if the received PPDU is an HE SU PPDU or HE TB PPDU, the other station may sequentially decode the L-SIG, HE-SIG-A, and MAC header. Also, if the received PPDU is an HE MU PPDU, the other station may sequentially decode the L-SIG, HE-SIG-A, HE-SIG-B, and MAC header. Also, if the received PPDU is an 11a / g PPDU, the other station may sequentially decode the L-SIG and MAC header.

[0222] The intended recipient of the PPDU or frame may include the intended recipient of the RU to which the PPDU is transmitted. The identifier used to determine whether the intended recipient is a RU may be a value determined based on the AID or MAC address of the station. The identifier used to determine whether the intended recipient is a RU may be an identifier indicating a station.

[0223] FIG. 25 shows a method for transmitting a response to a trigger frame by a multilink device according to an embodiment of the present invention when a NAV is set in the multilink device and the multilink device receives a trigger frame.

[0224] When a station transmits a response to a frame that triggers UL MU transmission, the station does not need to consider the intra-BSS NAV and the above-mentioned inter-link NAV. Specifically, when a station transmits a response to a frame that triggers UL MU transmission transmitted from a BSS in which the station is included, the station does not need to consider the intra-BSS NAV and the above-mentioned inter-link NAV. When a station transmits a response to a frame that triggers UL MU transmission transmitted by a multilink device in which the station is included, of a BSS in which the station is included, the station does not need to consider the intra-BSS NAV and the above-mentioned inter-link NAV. In this case, the station may be an AP.

[0225] When a station receives a trigger frame from a multilink device including a station that transmitted a frame setting the currently configured intra-BSS NAV or inter-link NAV and transmits a response to the trigger frame, the station does not need to consider the intra-BSS NAV or inter-link NAV. Also, when a station receives a trigger frame from a station that transmitted a frame setting the currently configured intra-BSS NAV or inter-link NAV and transmits a response to the trigger frame, the station does not need to consider the intra-BSS NAV or inter-link NAV.

[0226] In the above embodiment, the station not considering the NAV may mean that the station ignores the NAV even though the NAV is set, determines that the station is idle in virtual carrier sensing, or does not perform virtual carrier sensing.

[0227] In these embodiments, even if the AP multilink device sets the NAV for the non-AP multilink device, the AP multilink device can trigger the transmission of the non-AP multilink device, thereby enabling the AP multilink device to increase network efficiency.

[0228] In the embodiment of Figure 25, the non-AP multilink device includes a first station (STA1) and a second station (STA2). The first station (STA1) and the second station (STA2) operate on a first link (Link1) and a second link (Link2), respectively. The second station (STA2) sets its NAV based on a PPDU or frame transmitted to the first station (STA1). In this case, when the second station (STA2) receives a trigger frame triggered by the second station (STA2) from an AP associated with the second station (STA2) or an AP included in the multilink device including the AP associated with the second station (STA2), the second station (STA2) transmits a response to the trigger frame without considering the NAV set in the second station (STA2).

[0229] Although the present invention has been described above with reference to wireless LAN communication, the present invention is not limited thereto and may be equally applied to other communication systems such as cellular communication. Furthermore, although the method, apparatus, and system of the present invention have been described in relation to specific embodiments, some or all of the components and operations of the present invention may be implemented using a computer system having a general-purpose hardware architecture.

[0230] The features, structures, effects, etc. described in the above embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to one embodiment. Furthermore, the features, structures, effects, etc. exemplified in each embodiment can be combined or modified in other embodiments by a person skilled in the art to which the embodiment belongs. Therefore, content related to such combinations and modifications should be interpreted as being included within the scope of the present invention.

[0231] The above description has focused on the embodiments, but these are merely examples and do not limit the present invention. Those skilled in the art will understand that various modifications and applications not exemplified above are possible within the scope of the essential characteristics of the present invention. For example, each component specifically illustrated in the embodiments can be modified and implemented. Differences related to such modifications and applications should be construed as being included within the scope of the present invention as defined by the appended claims. [Explanation of symbols]

[0232] 100 Stations 110 processors 120 Communications Department 140 User Interface Section 150 display units 160 memory 200 AP 210 processors 220 Communications Department 260 memory

Claims

1. A non-access point (AP) multi-link device using multiple links, including a first link and a second link, wherein reception by the non-AP multi-link device on the second link is limited by internal leakage from the first link when the non-AP multi-link device transmits on the first link, and wherein the non-AP multi-link device: Transmitting and receiving unit and a processor; The processor: Using a channel access method, a channel in the first link and a channel in the second link are accessed, respectively, wherein the channel access method uses a backoff counter, an initial value of the backoff counter is set by an obtained random number, the backoff counter is decremented by one when the channel accessed by the channel access method is idle during a slot time, and when the value of the backoff counter is 0, a station of the non-AP multilink device is allowed to transmit; not transmitting on the first link even if a backoff counter for channel access on the first link reaches 0; The non-AP multilink device is configured as follows.

2. A non-AP multi-link device as described in claim 1, wherein when no transmission is performed on the first link, the processor is configured to maintain the value of the backoff counter for the channel access on the first link. Claim 3: A method of operating a non-access point (AP) multi-link device using multiple links, including a first link and a second link, wherein reception by the non-AP multi-link device on the second link is limited by internal leakage from the first link when the non-AP multi-link device transmits on the first link, the method comprising: accessing a channel in the first link and a channel in the second link using a channel access method, respectively; wherein the channel access method uses a backoff counter, an initial value of the backoff counter is set by an obtained random number, the backoff counter is decremented by one when the channel accessed by the channel access method is idle during a slot time, and when the value of the backoff counter is 0, a station of the non-AP multilink device is allowed to transmit; not transmitting on the first link even if a backoff counter for channel access on the first link reaches 0; A method comprising:

4. The method described in claim 3, wherein not transmitting on the first link includes maintaining the value of the backoff counter for the channel access on the first link.

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