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 use of mobile devices has become more widespread, wireless LAN technology that can provide them with high-speed wireless Internet services has been attracting attention. Wireless LAN technology is a technology that enables mobile devices such as smartphones, smart pads, laptop PCs, portable multimedia players, embedded devices, etc. to wirelessly connect to the Internet at home, in business, or in specific service areas based on short-distance wireless communication technology.

[0003] Since IEEE (Institute of Electronics Engineers) 802.11 supported the initial wireless LAN technology using the 2.4GHz frequency band, it has put into practical use or is currently developing various technology standards. First, IEEE 802.11b uses the 2.4GHz frequency band and supports a maximum communication speed of 11Mbps. IEEE 802.11a, which was commercialized after IEEE 802.11b, uses the 5GHz frequency band instead of the 2.4GHz band, reducing the impact of interference compared to the significantly more congested 2.4GHz frequency band, and uses OFDM technology to increase communication speeds to a maximum of 54Mbps. 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 satisfies backward compatibility, which has attracted considerable attention, but it also has an advantage over IEEE 802.11a in communication distance.

[0004] IEEE 802.11n is a technical standard established to overcome the communication speed limitations that have been pointed out as a weakness of wireless LAN. The purpose of IEEE 802.11n is to increase the speed and reliability of the network and to extend the operating distance of the wireless network. In detail, IEEE 802.11n supports a high throughput (HT) of up to 540Mbps or more in data processing speed, and is based on MIMO (Multiple Inputs and Multiple Outputs) technology that 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 the use of wireless LANs becomes more widespread and applications using them become more diverse, the need for new wireless LAN systems to support data throughput rates (Very High Throughput, VHT) higher than those supported by IEEE 802.11n is emerging. Among them, IEEE 802.11ac supports wide bandwidth (80MHz~160MHz) at 5GHz frequency. Although the IEEE 802.11ac standard is defined only in the 5GHz band, it is expected that initial 11ac chipsets will also support operation in the 2.4GHz band for backward compatibility with existing 2.4GHz band products. Theoretically, this standard allows multi-station wireless LAN speeds of at least 1Gbps and maximum single link speeds of at least 500Mbps. This is done by extending the air interface concepts accepted by 802.11n, such as wider radio frequency bandwidth (up to 160MHz), more MIMO spatial streams (up to 8), multi-user MIMO, and high density modulation (up to 256QAM). Also, 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, and is suitable for streaming large amounts of data and high bitrate videos such as uncompressed HD video. However, the 60GHz frequency band has the disadvantage that it is 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 in the final stages as the WLAN standard after 802.11ac and 802.11ad 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, it is necessary to provide high-frequency efficient communication indoors / outdoors in the presence of high density stations and APs (Access Points), and various technologies are being developed to realize this.

[0007] In addition, new WLAN standards have begun to be developed to increase maximum transmission speeds to support new multimedia applications such as high-definition video and real-time games. IEEE 802.11be (Extremely High Throughput, EHT), the 7th 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 multiple 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 an embodiment of the present invention, a multi-link device using a plurality of links includes a transceiver unit and a processor, and when the multi-link device transmits a plurality of PPDUs simultaneously through a plurality of links using the transceiver unit, the processor determines a transmission end time of the plurality of PPDUs based on whether the multi-link device transmits a frame requesting an 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 need to align the end of a PPDU among the multiple PPDUs that includes only frames that do not request an ACK with the end of a PPDU among the multiple PPDUs that includes a frame that requests an 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 among the multiple PPDUs that includes only frames that do not request an ACK is not delayed later than the end of a PPDU among the multiple PPDUs that includes frames that request an ACK.

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

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

[0015] The multilink device is an AP multilink device, and the processor can transmit the multiple 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 a plurality of links includes a transceiver unit and a processor, the multi-link device receives a plurality of PPDUs simultaneously through a plurality of links using the transceiver unit, and determines a transmission end time of the plurality of PPDUs based on whether a frame requesting an ACK is transmitted in the plurality of PPDUs.

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

[0019] An end of a PPDU including only frames not requesting ACK among the plurality of PPDUs may not be aligned with an end of a PPDU including a frame requesting 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 a frame that requests ACK among the plurality of PPDUs.

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

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

[0023] The multilink device is a non-AP multilink device, and the processor is capable of transmitting the multiple PPDUs from the AP multilink device using the receiving unit.

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

[0026] When no transmission is occurring on any one of the links, the processor may maintain a value of the backoff counter.

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

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

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

[0030] [Figure 1] FIG. 1 is a diagram showing a wireless LAN system according to an embodiment of the present invention. [Diagram 2] FIG. 11 is a diagram showing a wireless LAN system according to another embodiment of the present invention. [Diagram 3] FIG. 2 is a diagram showing a configuration of a station according to an embodiment of the present invention. [Figure 4] FIG. 2 is a diagram showing the configuration of an access point according to an embodiment of the present invention. [Diagram 5] 1 is a diagram illustrating a process in which a STA sets up 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 an example of various Extremely High Throughput (EHT) Physical Protocol Data Unit (PPDU) formats and a method for indicating the same according to an embodiment of the present invention. [Figure 9] 1 illustrates 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] 4 illustrates an operation in which a multi-link device according to an embodiment of the present invention finishes transmission simultaneously on multiple links. [Figure 12] 1 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] It is shown that when a multi-link device according to an embodiment of the present invention transmits on one of the links, the multi-link device postpones transmission on the other links. [Figure 14] 1 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 the multilink device transmits on a plurality of links. [Figure 16] 1 illustrates how a multi-link device according to an embodiment of the present invention operates using a mapping between links and TIDs. [Figure 17] 4 illustrates an operation of a station performing UL MU transmission according to an embodiment of the present invention. [Figure 18] 13 illustrates a multi-link device according to an embodiment of the present invention aggregating multi-TIDs. [Figure 19] 1 illustrates an element for signaling information regarding link and TID mapping according to an embodiment of the present invention. [Figure 20] 1 shows a station according to an embodiment of the present invention making channel access to transmit a trigger frame. [Figure 21] 4 illustrates an operation of a multi-link device performing transmission over multiple links according to an embodiment of the present invention. [Figure 22] 4 shows an operation of a multi-link device according to an embodiment of the present invention for setting a NAV. [Figure 23] 4 shows an operation of a multi-link device according to an embodiment of the present invention for setting a NAV. [Figure 24] In the embodiment of the present invention, a station in the multi-link device indicates resuming channel access or transmission after the channel access or transmission is suspended by a PPDU received by another station in the multi-link device. [Diagram 25] 13 shows a method in which the multilink device transmits 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 PREFERRED EMBODIMENTS

[0031] The terms used in this specification are selected as general terms that are currently widely used as much as possible in consideration of the functions of the present invention, but this may vary depending on the intentions, customs, or the emergence of new technologies of the engineers in the relevant technical field. In addition, in certain cases, the applicant may arbitrarily select terms, and in such cases, the meanings of the terms will be described in the description of the relevant invention. Therefore, it is clear that the terms used in this specification should be interpreted not simply as terms, but based on the substantial meanings of the terms and the contents of this specification as a whole.

[0032] Throughout the specification, when a component is "connected" to another component, this includes not only when it is "directly connected" to another component, but also when it is "electrically connected" with another component in between. Furthermore, when a component "includes" a particular component, this means that it may further include the other component, not excluding the other component, unless otherwise specified to the contrary. In addition, limitations such as "greater than" or "less than" based on a particular critical value may be appropriately replaced with "more than" or "less than" 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 (BSS), which are a set of devices that can successfully 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, infrastructure BSS BSS1, BSS2 includes one or more stations STA1, STA2, STA3, STA4, STA5, access points AP-1, AP-2 which are stations providing a distribution service, and a distribution system DS which connects multiple access points AP-1, AP-2.

[0037] A station (STA) is any device including a medium access control (MAC) and a physical layer interface for a wireless medium according to the IEEE 802.11 standard, and in a broad sense includes 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 further includes a user interface unit and a display unit, etc., depending on the embodiment. The processor generates frames to be transmitted through a wireless network, processes frames received through 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 through the wireless network for the station. In the present invention, the term "terminal" is used to include a 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 a station associated therewith. In an infrastructure BSS, communication between non-AP stations is generally performed via the AP, but when a direct link is set up, direct communication is possible between non-AP stations. Meanwhile, in the present invention, AP is used as a concept including a personal BSS coordination point (PCP), but in a broad sense, AP includes all 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, AP is also referred to as a base wireless communication terminal, but in a broad sense, the 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 in communication with a plurality of wireless communication terminals.

[0039] A plurality of infrastructure BSSs are connected to each other via a distribution system DS. In this case, a plurality of BSSs connected to each other via the distribution system is 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 which the same or corresponding parts in the embodiment of FIG. 2 are the same as or correspond to the embodiment of FIG.

[0041] BSS3 shown in Figure 2 is an independent BSS and does not include an AP, so all stations (STA6, STA7) are not 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 a configuration of a station 100 according to an embodiment of the present invention. As shown in the figure, 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 wireless LAN packets, and may be built into or externally provided in 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 of 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 of 7.125 GHz or more and a communication module using a frequency band of 7.125 GHz or less. Each communication module may perform wireless communication with an AP or an external station based on the wireless LAN standard of the frequency band supported by the communication module. The communication unit 120 may operate only one communication module at a time or operate multiple communication modules simultaneously according to the performance and requirements of the station 100. When the station 100 includes multiple communication modules, each communication module may be provided in an independent form, or multiple modules may be integrated into one chip. In an 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 a command from the processor 110 using various output means.

[0045] Then, 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 performed by the processor 110 or a control command of the processor 110. The memory 160 also stores control programs used by the station 100 and various data associated therewith. Such control programs include connection programs 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 transmission and reception of data between the units. According to an embodiment of the present invention, the processor 110 executes a program for connection to an AP stored in the memory 160 and receives a communication setup message transmitted by the AP. The processor 110 also reads information on the priority conditions of the station 100 included in the communication setup message and requests a connection to the AP based on the information on the priority conditions of the station 100. The processor 110 of the present invention may refer to a main control unit of the station 100, or may refer to a control unit for individually controlling some components of the station 100, for example, the communication unit 120, depending on the embodiment. That is, the processor 110 may be a modem that modulates and demodulates a wireless signal transmitted and received from the communication unit 120, or a modulator and / or demodulator. The processor 110 controls various operations of transmitting and receiving wireless signals of the station 100 according to an embodiment of the present invention. A detailed embodiment of the present invention 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 are used to logically distinguish the elements of the device. Thus, the above-mentioned device elements may be mounted on one chip or multiple chips depending on the design of the device. For example, the processor 110 and the communication unit 120 may be integrated and embodied on one chip, or may be embodied on separate chips. In addition, in an embodiment 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 a configuration of an AP 200 according to an embodiment of the present invention. As shown in the figure, 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, a duplicated description 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 a plurality of 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, any of 2.4 GHz, 5 GHz, 6 GHz, and 60 GHz. Preferably, the AP 200 may include a communication module using a frequency band of 7.125 GHz or higher and a communication module using a frequency band of 7.125 GHz or lower. 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 operate multiple communication modules simultaneously according to the performance and requirements of the AP 200. In the embodiment of the present invention, the communication unit 220 may represent an RF communication module that processes RF (Radio Frequency) signals.

[0050] Next, the memory 260 stores control programs used in the AP 200 and various data associated therewith. Such control programs include a connection program for managing station connections. Also, the processor 210 controls each unit of the AP 200 and controls transmission and reception of data between the units. According to an embodiment of the present invention, the processor 210 executes a program for connection with a station stored in the memory 260 and transmits a communication setting message to one or more stations. At this time, the communication setting message includes information regarding connection priority conditions of each station. Also, the processor 210 performs connection setting in response to a connection request of a station. 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 of transmitting and receiving wireless signals of the AP 200 according to an embodiment of the present invention. A detailed embodiment thereof 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, the link between the STA 100 and the AP 200 is set up through three steps: scanning, authentication, and association. First, the scanning step is a step in which the STA 100 acquires connection information of the BSS operated by the AP 200. There are two methods for performing scanning: 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 has successfully received wireless connection information in the scanning step transmits an authentication request (S107a), receives an authentication response from the AP 200 (S107b), and performs an authentication step. After the authentication step is performed, the STA 100 transmits an association request (S109a), receives an association response from the AP 200, and performs an association step (S109b). In this specification, association basically means wireless association, but the present invention is not limited thereto, 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, the server 300 is a server that processes 802.1X-based authentication with the STA 100, and may be physically connected to the AP 200 or may exist as a separate server.

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

[0056] A terminal performing wireless LAN communication performs carrier sensing before transmitting data to check whether a channel is occupied or not. If a wireless signal of a certain strength or more 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 the signal is detected is called the CCA threshold. If a wireless signal of a strength greater than 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 of a strength less than the CCA threshold is detected, the channel is determined to be idle.

[0057] If the channel is determined to be in an idle state, each terminal having data to transmit performs a backoff procedure after an IFS (Inter Frame Space) according to the status of each terminal, for example, an AIFS (Arbitration IFS) or a PIFS (PCF IFS). In some embodiments, the AIFS is used as a configuration to replace the conventional DIFS (DCF IFS). Each terminal waits while decreasing a slot time of a random number determined for the corresponding terminal during an interval of the idle state of the channel, and a terminal that has exhausted all the slot time attempts to access the corresponding channel. In this manner, a section in which each terminal performs a backoff procedure is called a contention window section. At this time, the random number can be called a backoff counter. That is, an initial value of the backoff counter is set by an integer that is a random number obtained by the terminal. If the terminal detects that the channel is idle during the slot time, the terminal can decrease the backoff counter by 1. Also, if the backoff counter reaches 0, the terminal may be allowed to perform channel access on the corresponding channel. Thus, a terminal may be allowed to transmit if the channel is idle during the AIFS time and the backoff counter slot time.

[0058] If a specific terminal succeeds in accessing the channel, the terminal transmits data through 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 random numbers newly assigned to each terminal are determined within a range (2*CW) twice the range (contention window, CW) of the random numbers previously assigned to the terminal. Meanwhile, each terminal attempts access by performing a backoff procedure again in the next contention window period, and at this time, each terminal performs the backoff procedure from the slot time remaining in the previous contention window period. In this manner, each terminal performing wireless LAN communication can avoid collision with each other on a specific channel.

[0059] <Examples of various PPDU formats>

[0060] FIG 7 shows an example of various standard generation PPDU (PLCP Protocol Data Unit) formats. More specifically, FIG 7(a) shows an example of a legacy PPDU format based on 802.11a / g, FIG 7(b) shows an example of a HE PPDU format based on 802.11ax, and FIG 7(c) shows an example of a non-legacy PPDU (i.e., EHT PPDU) format based on 802.11be. Also, FIG 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 RL-SIG (Repeated Legacy Short Training field), a HE-SIG-A (High Efficiency Signal A field), a HE-SIG-B (High Efficiency Signal B field), a HE-STF (High Efficiency Short Training field), and a HE-LTF (High Efficiency Long Training field) 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 be modified according to the HE PPDU format. For example, the 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 RL-SIG (Repeated Legacy Short Training field), a U-SIG (Universal Signal field), an EHT-SIG-A (Extremely High Throughput Signal A field), an EHT-SIG-A (Extremely High Throughput Signal B field), an EHT-STF (Extremely High Throughput Short Training field), and an EHT-LTF (Extremely High Throughput Long Training field) 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 can be called an EHT preamble. The specific configuration of the non-legacy preamble may be modified according to the EHT PPDU format. For example, EHT-SIG-A and EHT-SIG-B may be used only in some formats of the EHT PPDU format.

[0064] The L-SIG field included in the preamble of the PPDU is configured with a total of 64 subcarriers by applying 64 FFT OFDM. Of these, 48 subcarriers excluding the guard subcarriers, DC subcarriers, and pilot subcarriers are used for L-SIG data transmission. Since BPSK and Rate=1 / 2 MCS (Modulation and Coding Scheme) are applied to the L-SIG, it can contain a total of 24 bits of information. Figure 7(d) shows the 24-bit information configuration 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 speeds of 6 / 9 / 12 / 18 / 24 / 36 / 48 / 54 Mbps, which is a combination of a modulation method such as BPSK / QPSK / 16-QAM / 64-QAM and a code rate such as 1 / 2, 2 / 3, or 3 / 4. The total length of the PPDU can be indicated by combining the information in the L_RATE field and the L_LENGTH field. In the non-legacy PPDU format, the L_RATE field is set to the minimum speed of 6 Mbps.

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

[0067] First, a method in which a legacy or non-legacy terminal analyzes the length of the PPDU using the L_LENGTH field is 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 one symbol duration of 64 FFT. Therefore, the number of 64 FFT reference symbols after the L-SIG is obtained by adding 3 bytes corresponding to the SVC field and the Tail field to the L_LENGTH field value and dividing it by 3 bytes, which is the transmission amount of one symbol. The length of the PPDU, i.e., the reception time (RXTIME), is obtained by multiplying the obtained number of symbols by 4 us, which is one symbol duration, and adding 20 us for the transmission of the L-STF, L-LTF, and L-SIG. This can be expressed as the following Equation 1.

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

[0075] The VI bit will maintain the current bit configuration, and even if a subsequent generation PPDU is defined, a current 11be terminal can obtain information about the PPDU from the VI field of the PPDU. To this end, the VI field is composed of PHY version, UL / DL, BSS color, TXOP, and Reserved fields. The PHY version field is 3 bits, and serves to sequentially distinguish 11be and subsequent generation WLAN standards by version. 11be has a value of 000b. The UL / DL field distinguishes whether the corresponding PPDU is an uplink / downlink PPDU. The BSS color means a BSS-specific identifier defined in 11ax, and has a value of 6 bits or more. The TXOP means a transmit opportunity duration that was transmitted in the MAC header, but by adding it to the PHY header, the length of the TXOP containing the corresponding PPDU can be inferred without decoding the MPDU, and has a value of 7 bits or more.

[0076] The VD field may be composed of fields commonly used in any PPDU format, such as PPDU format and BW, which are signaling information useful only for PPDUs of the 11be version, and fields defined differently for each PPDU format. The PPDU format is a division factor that distinguishes EHT SU (Single User), EHT MU (Multiple User), EHT TB (Trigger-based), EHT ER (Extended Range) PPDU, etc. The BW field mainly signals five basic PPDU BW options of 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), and various remaining PPDU BWs formed by preamble puncturing. After being signaled at 320 MHz, some 80 MHz may be signaled in a punctured form. Also, the punctured and modified channel shape may be directly signaled in the BW field, or may be signaled using both the BW field and a field that appears after the BW field (e.g., 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. The MU PPDU and the SU PPDU may be signaled in the same PPDU format, and a field for distinguishing the MU PPDU from the SU PPDU may be located before the EHT-SIG field, and additional signaling may be performed for this purpose. Both the SU PPDU and the MU PPDU include an EHT-SIG field, but some fields that are not necessary in the SU PPDU may be compressed. In this case, the information of the compressed field may be omitted or may have a reduced size compared to the size of the original field included in the MU PPDU. For example, in the case of the SU PPDU, the common field of the EHT-SIG may be omitted or replaced, or the user-specific field may be replaced or reduced to one, and may have a different configuration.

[0078] Alternatively, the SU PPDU may further include a compression field indicating whether or not it is compressed, and some fields (eg, the RA field, etc.) may be omitted depending on the value of the compression field.

[0079] When a part 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, etc.). In the case of the 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 transmitted to itself. 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 of the EHT-SIG field and / or MCS, which is a modulation method. The EHT-SIG field may include the size and location information of the RU assigned to each user.

[0080] In the case of a 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 receive the SU PPDU efficiently only by recognizing the RUs punctured in between. Therefore, the AP can transmit the SU PPDU including information on the punctured RUs among the RUs assigned to the STA (e.g., the puncturing pattern of the RUs, etc.). That is, in the case of a 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 may signal the type of discontinuous channels that appear within the bandwidth.

[0081] The form of the 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, in the case of a SU PPDU, since it is a PPDU transmitted only to a single UE, the STA can recognize the bandwidth allocated to itself from the BW field included in the PPDU, and can recognize the punctured resources of 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 except for the specific channel of the punctured resource unit. In this case, the 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 SU PPDU. Since puncturing may be performed for each 20 MHz subchannel, if puncturing is performed for a BW having multiple 20 MHz subchannels such as 80, 160, and 320 MHz, in the case of 320 MHz, the discontinuous channel type (when only the end 20 MHz is punctured and considered as discontinuous) must be signaled by expressing whether or not the remaining 15 20 MHz subchannels except the primary channel are used. In this way, using 15 bits to signal discontinuous channel types for single user transmission may result in excessive signaling overhead when considering the low transmission speed of the signaling part.

[0083] The present invention proposes a method for signaling the discontinuous channel type of SU PPDU, and illustrates the discontinuous channel type determined by the proposed method. In addition, a method for signaling the puncturing types of primary 160 MHz and secondary 160 MHz in the 320 MHz BW configuration of SU PPDU is proposed. 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, in one embodiment of the present invention, a method is proposed in which the configuration of the PPDU indicated by the preamble puncturing BW value is different depending on the PPDU format signaled in the PPDU format field. Assuming that the BW field is 4 bits, in the case of EHT SU PPDU or TB PPDU, one symbol of EHT-SIG-A is further signaled after U-SIG, or EHT-SIG-A does not need to be signaled from the beginning, so that up to 11 puncturing modes must be completely signaled using only the BW field of U-SIG in consideration of this. However, in the case of EHT MU PPDU, EHT-SIG-B is further signaled after U-SIG, so up to 11 puncturing modes can be signaled in a different manner from SU PPDU. In the case of EHT ER PPDU, the BW field is set to 1 bit, and it is possible to signal whether the PPDU uses a 20 MHz or 10 MHz band. Detailed puncturing patterns for each PPDU type will be described in detail below with reference to FIG. 11 and FIG. 12.

[0085] FIG. 7(f) shows the format-specific field configuration of the VD field when the PPDU format field of the U-SIG indicates EHT MU PPDU. In the case of MU PPDU, SIG-B, which is a signaling field for simultaneous reception by multiple users, is required, and SIG-B may be transmitted after U-SIG without a separate SIG-A. For this purpose, U-SIG must signal information for decoding SIG-B. Such fields include 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 a method for indicating the same according to an embodiment of the present invention.

[0087] 8, a PPDU may be composed of a preamble and a data portion, and the format of an EHT PPDU, which is one type, may be distinguished by a U-SIG field included in the preamble. Specifically, whether the format of the PPDU is an 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] Fig. 8(d) shows an example of an EHT ER SU PPDU format used for single-user transmission with an STA in an extended range. The EHT ER SU PPDU may be used for single-user transmission with a STA in a wider range than the EHT SU PPDU described in Fig. 8(a), and the U-SIG field may be repeatedly positioned on the time axis.

[0092] The EHT MU PPDU described in (c) of FIG. 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 PPDU transmitted through the user specific field of the EHT-SIG-B to the STA. 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 a resource unit configuration (e.g., a resource unit division form) in a specific bandwidth (e.g., 20 MHz, etc.) on the frequency axis. That is, the RA field may indicate a resource unit configuration divided by a bandwidth for transmitting the HE MU PPDU so that the STA receives the PPDU. Information on 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, a user field corresponding to at least one resource unit used for data transmission among the multiple divided resource units may include the AID of a receiver or sender, and a user field corresponding to the remaining resource units not used for data transmission may include a null STA ID that has already been set.

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

[0096] When one wireless communication device communicates using multiple links, the communication efficiency of the wireless communication device can be improved. In this case, the link is a physical path, and may be configured as one wireless medium that can be used to transmit MSDU (MAC service data unit). For example, when the frequency band of any one link is being used by another wireless communication device, the wireless communication device can continue to communicate using another link. In this way, the wireless communication device can effectively use multiple channels. Also, when the wireless communication device simultaneously communicates using multiple links, the overall throughput can be increased. However, the existing wireless LAN is specified on the premise that one wireless communication device uses one link. For this reason, a wireless LAN operation method for using multiple links is required. A wireless communication method of a wireless communication device using multiple links will be described with reference to Figs. 9 to 26. First, a specific form 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] For the wireless communication method using the above-mentioned multiple links, a multi-link device (MLD) may be defined. The multi-link device may represent a device having one or more affiliated stations. According to a specific embodiment, the multi-link device may represent a device having two or more affiliated stations. Also, the multi-link device may exchange a multi-link element. The multi-link element includes information on 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 called a multi-link logical entity (MLLE) or a multi-link entity (MLE). The multi-link device may have one MAC service access point (SAP) up to a logical link control (LLC). Also, the MLD may have one MAC data service.

[0099] The stations included in the multilink device can operate on multiple links. Also, the stations included in the multilink device can operate on multiple channels. Specifically, the stations included in the multilink device can operate on different links or different channels. For example, the stations included in the multilink device can operate on different channels of 2.4 GHz, 5 GHz, and 6 GHz.

[0100] The operation of the multilink device may be referred to as multilink operation, MLD operation, or multi-band operation. If a station associated with the multilink device is an AP, the multilink device may be referred to as AP MLD. If a station associated with the multilink device is a non-AP station, the multilink device may 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 through a first link (Link1). Also, the second AP (AP2) and the second non-AP STA (non-AP STA2) communicate through a second link (Link2). Also, the third AP (AP3) and the third non-AP STA (non-AP STA3) communicate through a third link (Link3).

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

[0103] The multilink setting may be set by negotiation between peer stations. Specifically, the multilink setting may be set by communication between stations without communication with the AP. The multilink setting may be set through any one of the links. For example, even if the first link to the third link are set through the multilink, the multilink setting may be set through the first link.

[0104] Also, a mapping between a traffic identifier (TID) and a link may be set. Specifically, a frame corresponding to a specific TID value may be exchanged only through a link designated in advance. The mapping between a TID and a link may be set on a directional-based basis. For example, when a plurality of links are set between a first multilink device and a second multilink device, the first multilink device may be set to transmit a frame of a first TID to a plurality of first links, and the second multilink device may be set to transmit a frame of a second TID to the first link. Also, a default setting may exist for the mapping between a TID and a link. Specifically, when there is no additional setting in the multilink setting, the multilink device may exchange frames corresponding to a TID in each link according to a default setting. In this case, the default setting may be that all TIDs are exchanged in any one link.

[0105] The TID will be specifically described. The TID is an ID for classifying traffic and data to support QoS (quality of service). 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). The TID may be classified into 16 types. For example, the TID may be designated as one of 0 to 15. The TID value to be used may be designated differently depending on an access policy, a channel access, or a medium access method. For example, when EDCA (enhanced distributed channel access) or HCAF (hybrid coordination function contention based channel access) is used, the TID value may be assigned in the range of 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. Also, 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. Also, 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 channel contention in EDCA. 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 ACs. For example, AC_VI may be subdivided into AC_VI primary and AC_VI alternate. AC_VO may be subdivided into AC_VO primary and AC_VO alternate. UP or TID may be mapped to 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 a higher priority in that order. That is, 1 may have a lower priority, and 7 may have a higher priority. Therefore, the priority may be higher in the order of AC_BK, AC_BE, AC_VI, and AC_VO. Also, AC_BK, AC_BE, AC_VI, and AC_VO may correspond to ACI (AC index) 0, 1, 2, and 3, respectively. Due to the characteristics of such a TID, the mapping between a TID and a link may represent the mapping between an AC and a link.Additionally, the mapping between links and ACs can represent the mapping between TIDs and links.

[0107] As described above, a TID may be mapped to each of a plurality of links. The mapping may be a designation of a link through which traffic corresponding to a particular TID or AC may be exchanged. Also, a TID or AC that may be transmitted for each transmission direction within a link may be designated. As described above, there may be a default setting for mapping between a TID and a link. Specifically, if there is no additional setting in the multilink setting, 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 the 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-mentioned 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 in operation or where channel conditions are good. The above-mentioned TID-to-link mapping may also allow stations to stay in a power saving state for a longer period of time.

[0110] FIG. 10 illustrates a multi-link operation in which transmissions on different links are simultaneous according to an embodiment of the present invention.

[0111] Depending on the implementation of the multilink device, it may not be supported that the multilink device transmits on multiple links simultaneously, receives on multiple links simultaneously, or transmits on one link and receives on another link simultaneously. This is because reception or transmission on one link may affect reception or transmission on another link. Specifically, transmission on one link may act as interference on another link. Interference from one link of one multilink device acting on another link may be called internal leakage. The smaller the frequency interval between the links, the larger the internal leakage may be. If the internal leakage is not too large, transmission on another link may be performed when transmission on one link is performed. If the internal leakage is large, transmission on another link may not be performed when transmission on one link is performed. In this way, the multilink device transmits on multiple links simultaneously, transmits on one link and receives on another link simultaneously, or receives on multiple links simultaneously may be called STR (simultaneous transmit and receive, simultaneous transmission and reception). As described above, the 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, when the multilink device operates with a single radio, the multilink device may not perform STR. Also, when the multilink device operates with a single antenna, the multilink device may not perform STR. Also, when internal leakage is detected to be equal to or greater than a predetermined value, the multilink device may not perform STR.

[0112] A station may exchange information on the STR capability of the station with other stations. Specifically, a station may exchange information on whether the ability of the station to transmit or receive on multiple links is limited with other stations. Specifically, the information on whether the ability of the station to transmit or receive on multiple links is limited may indicate whether the station can transmit or receive on multiple links simultaneously, or whether transmission and reception can be performed simultaneously. In addition, the information on whether the ability of the station to transmit or receive on multiple links is limited may be information indicated in stages. Specifically, the information on whether the ability of the station to transmit or receive on multiple links is limited may be information indicating a stage indicating how large the internal leakage is. In a specific embodiment, the information indicating a stage indicating how large the internal leakage is may be information indicating a stage indicating the magnitude of interference generated by the internal leakage. In yet another specific embodiment, the information may be information indicating a stage indicating how large the frequency interval between links that may affect the internal leakage is. In addition, the information indicating a stage indicating how large the internal leakage is may be information indicating a relationship between the frequency interval between links and the magnitude of the internal leakage in stages.

[0113] In FIG. 10, a first station (STA1) and a second station (STA2) are associated with one non-AP multilink device. Also, a first AP (AP1) and a second AP (AP2) may 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 data through the second link (Link2), the first station (STA1) may be interfered with in receiving data through the first link (Link1). For example, the second station (STA2) transmits first data (Data1) through 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) via a second link (Link2). At this time, the transmission time of the second data (Data2) may overlap with the transmission time of the response (Ack for Data1) to the first data (Data1). At this time, the transmission to the second station (STA2) via the second link (Link2) may cause interference to the first link (Link1). As a result, the first station (STA1) may not be able to receive the response (Ack for Data1) to the first data (Data1). Figure 10(a) shows a case where transmission starts simultaneously on multiple links. However, as shown in Figure 10(b), transmission may start at different times on multiple links.

[0114] Specifically, the multilink device may perform channel access, for example, backoff, independently on a plurality of links. In this case, the backoff counters of the plurality of links may reach 0, and transmission may begin simultaneously on the plurality of links. In yet another specific embodiment, when the backoff counter of any one of the links of the multilink device reaches 0, the multilink device may perform only energy detection (ED) on the corresponding link and other links and then perform channel access. When energy of a certain magnitude or more is not detected, the multilink device may perform channel access on the link on which the energy detection has been performed. This allows the multilink device to begin transmission simultaneously on the plurality of links. The threshold value used for energy detection may be smaller than the threshold value used when determining whether to decrease the backoff counter. In addition, when determining whether to decrease the backoff counter, the station may detect any type of signal, not just a WLAN signal. In addition, in the above-mentioned energy detection, the station may 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 the signal detected by the 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, the multilink device may decrement the backoff counter in one of the links while transmission is occurring in the other links, as shown in FIG. 10(a) and FIG. 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] A case where a plurality of PPDUs are transmitted simultaneously or can be transmitted simultaneously through a plurality of links will be described with reference to Figures 11 to 15. The embodiment described with reference to Figures 11 to 15 may be applied to a case where STR is not possible through a plurality of links through which a plurality of PPDUs are transmitted. The embodiment described with reference to Figures 11 to 15 may be applied to a case where a multilink device that receives a plurality of PPDUs cannot receive through another link when transmitting through any one of the links. The embodiment described with reference to Figures 11 to 15 may be applied to a case where a multilink device that transmits a plurality of PPDUs cannot receive through another link when transmitting through any one of the links.

[0117] FIG. 11 illustrates an operation of a multilink device according to an embodiment of the present invention for simultaneously completing transmission on multiple links.

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

[0119] While a response frame to the transmission of the multilink device is transmitted on one link, the multilink device may prevent the multilink device from transmitting on another link. 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 ACK. The multilink device may end transmission simultaneously on multiple links based on whether the frame transmitted by the multilink device requests ACK. That is, the multilink device may end transmission simultaneously on multiple links based on whether the frame included in at least one of the multiple PPDUs requests ACK. Whether a frame requests 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 ACK. Also, if the type and subtype of the frame are "Action No Ack Frame", the multilink device may determine that the frame does not request ACK. The ACK policy, the type and subtype of the frame may be indicated in the MAC header of the frame. Also, as in the embodiment of FIG. 11, the frame requesting 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 FIG. 11, the multilink device cannot receive on any other link while transmitting on any one link. The first station (STA1) and the second station (STA2) of the multilink device transmit the first data (Data1) and the second data (Data2), respectively. The first station (STA1) and the second station (STA2) simultaneously finish transmitting the first data (Data1) and the second data (Data2), respectively. 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 illustrates 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 starts transmission on multiple links simultaneously, the multilink device may not be allowed to end transmission on the other link later than transmission on one of the links. Therefore, the multilink device can end transmission on the other link before or at the same time as transmission on one of the links. Specifically, when a multilink device starts transmission on another link while transmitting on one of the links 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 at the same time as transmission on one of the links. At this time, the response frame may be an immediate response frame. The immediate response frame may represent a case where the interval between a frame and a response frame is within a pre-specified time interval. At this time, the pre-specified time interval may be SIFS. In addition, 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 the 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 the 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 in which a response frame is not expected on any one of the links, the multilink device may be allowed not to end transmission on the other links before the end of transmission on any one of the links. Thus, when a multilink device performs transmission in which a response frame is not expected on any one of the links, the multilink device may end transmission on the other links after the end of transmission on any one of the links. When a multilink device performs transmission in which a response frame is not expected on any one of the links 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 links before the end of transmission on any one of the links. In this case, the response frame may be an immediate response frame. Thus, when a multilink device transmits only a plurality of PPDUs that do not include a frame requesting a response, or transmits one PPDU including a frame requesting a response and a PPDU requesting a response simultaneously, the multilink device does not need to end transmission of a plurality of PPDUs simultaneously. In this case, the multi-link device can transmit multiple PPDUs such that the end point of transmission of a PPDU including only frames not requesting a response is not later than the end point of transmission of a PPDU including a frame requesting a response.

[0123] In the embodiment of FIG. 12, the multi-link device cannot receive on any other link while transmitting on any 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. 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] Also, the above-described embodiment may be applied when a multi-link device is unable to receive on one link while transmitting on the other link.

[0125] FIG. 13 illustrates a case in which, 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 only through one of the multiple links. For example, when the multilink device transmits through one of the links and cannot receive through the other links, the multilink device can transmit only through one of the multiple links. In these embodiments, the multilink device can postpone transmission during channel access. The channel access described in this specification may mean channel access including a backoff procedure described above with reference to FIG. 6. Specifically, the multilink device can postpone transmission through the remaining links except for the one link that transmits. For example, the multilink device can perform a backoff procedure on multiple links. At this time, the multilink device can transmit through the link whose backoff counter reaches 0 first and reset the backoff counters on the remaining links. Also, when the backoff counters of the multiple links reach 0, the multilink device can transmit through one of the multiple links. At this time, the multilink device can randomly select one of the multiple links and transmit through the selected link. Also, 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 of the links and cannot receive on the other links.

[0127] In yet another specific embodiment, the multilink device can determine a method of performing channel access on multiple links according to 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 channel access independently 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 channel access independently on multiple links.

[0128] As shown in Figures 11 and 12, the multilink device can adjust the length of the PPDU to comply with the constraints due to the concurrency conditions. In this case, 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 on one of the multiple links. Also, if the transmission time allowed on one link is shorter than the traffic to be transmitted on that link, the multilink device can postpone transmission on that link. For example, according to the embodiments of Figures 11 and 12, the transmission time allowed on a link may be shorter than the traffic to be transmitted on that link.

[0129] In the embodiment of Fig. 13, the multilink device performs channel access including backoff independently for the first link (Link1) and the second link (Link2). The backoff counter for the first link (Link1) and the backoff counter for the second link (Link2) reach 0 at the same time. 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 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 as it is. This ensures transmission balance between links that may be degraded by the postponement of transmission.

[0131] FIG. 14 illustrates 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 the multilink device transmits through multiple links, the multilink device can end transmission through multiple links simultaneously. Specifically, the multilink device can end transmission of PPDUs through multiple links simultaneously. Ending transmission of multiple PPDUs simultaneously can be referred to as aligning the ends of the PPDUs. Also, when the difference between the transmission end points of multiple PPDUs is smaller than or smaller or equal to a threshold value, it can be said that the ends of multiple PPDUs are aligned. In this case, the threshold value may be a value specified in advance. Specifically, the threshold value may be a value set based on the SIFS. Also, 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 combined value of the SIFS and the length of the signal extension by 2. In this case, the threshold value may be 8us.

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

[0134] The receiver multilink device may be a non-STR multilink device. When the sender multilink device transmits multiple PPDUs to the 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. Thus, when the AP multilink device transmits multiple PPDUs to the 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 the 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 the 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 called downlink (DL). Also, the transmission direction from the non-AP STA or non-AP multilink device to the AP or AP multilink device can be called 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 called 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 called 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 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 one multilink device via multiple links. For example, the receiver multilink device operates on a first link and a second link. A first station of the receiver multilink device operates on the first link, and a second station of the receiver multilink device operates on the second link. While a first PPDU is transmitted to the first station via the first link, a second PPDU is transmitted to the second station via the second link, and when 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-mentioned embodiment, the transmission of multiple PPDUs over multiple links may mean that multiple PPDUs are transmitted simultaneously. Also, the transmission of multiple PPDUs over multiple links may mean that multiple PPDUs are transmitted simultaneously at any time. The transmission of multiple PPDUs simultaneously may mean that multiple PPDUs are transmitted simultaneously at a time even if their transmission start times are not the same. The transmission of multiple PPDUs simultaneously may mean that multiple PPDUs are transmitted simultaneously at a time even if their transmission end times are not the same.

[0140] In yet another specific embodiment, when at least one of the multiple PPDUs transmitted through the multiple links includes a high priority frame, the multilink 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. In this way, the multilink device can increase the transmission efficiency of the high priority frames.

[0141] In the above-described embodiment, when only some of the PPDUs satisfy a pre-specified condition, the multilink device may align only the ends of some of the PPDUs that satisfy the pre-specified condition. When the multilink device transmits a plurality of PPDUs, the multilink device may align the ends of the plurality of PPDUs that include a frame requesting an immediate response among the plurality of PPDUs. For example, when only two of the plurality of PPDUs include a frame requesting an immediate response, the multilink device may align only the ends of the two PPDUs that include a frame requesting an immediate response among the plurality of PPDUs. In these embodiments, the multilink device may not align the ends of the PPDUs that do not include a frame requesting an immediate response with the ends of the plurality of PPDUs that include a frame requesting an immediate response. Specifically, the multilink device may transmit the ends of the PPDUs that do not include a frame requesting an immediate response so that the ends of the PPDUs that do not include a frame requesting an immediate response are not later than the ends of the PPDUs that include a frame 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). Also, 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. Each of 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 each of the first station (STA1), the second station (STA2), and the third station (STA3), using a first link (Link1), a second link (Link2), and a third link (Link3), respectively. 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) not requesting 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 illustrates an operation of a multilink device according to 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 a plurality of PPDUs to a receiver multilink device through a plurality of links, the sender multilink device can determine the transmission length of each of the plurality of PPDUs depending on whether each of the plurality of 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 is to be the same as or earlier than the end of transmission of a PPDU that includes a frame requesting an immediate response. Thus, the sender multilink device can determine that the end of transmission of a PPDU that includes a frame requesting an immediate response is to 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). Also, 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 a first data (Data1) that requests an immediate response, and the second PPDU (PPDU2) includes only a second data (Data2) that does not request an immediate response. In this case, the second data (Data2) may be an A-MPDU including only MPDUs that do not request an immediate response. Also, the receiver of the first data (Data1) may be the first station (STA1), and the receiver of the second data (Data2) may be the second station (STA1). Also, 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) such 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 transmission start time of the PPDU. Specifically, as shown in FIG. 15(a), the transmission start of the first PPDU (PPDU1) may be earlier than the transmission start 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 Figs. 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 illustrates 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 of the links may be transmitted through the link. For example, an A-MPDU (aggregate-MPDU) transmitted through any one of the links may be an aggregate of an MPDU corresponding to a TID mapped to the link and an MPDU corresponding to a TID not mapped to the link. In addition, a PPDU transmitted through any one of the links may include an MPDU corresponding to a TID mapped to the link and an MPDU corresponding to a TID not mapped to the link. Thus, exceptions to the mapping between TIDs and links include:

[0150] Specifically, when a restriction is applied to the end time of transmission in any one link, a frame corresponding to a TID not mapped to the link may be transmitted in the link. In a specific embodiment, when the multilink device performs transmission, the multilink device may set the end time of transmission of the second link based on the end time of transmission 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. In addition, 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 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 based on the comparison result. For example, when 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 multilink device can transmit both an MPDU corresponding to the TID mapped to the link and an MPDU corresponding to a 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 the link and MPDUs corresponding to the TID not mapped to the 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) through the second link (Link2). Specifically, the non-AP multilink device transmits a PPDU including an MPDU that is mapped to a first TID (TID0) that is mapped to the second link (Link2) and an MPDU that is corresponding to a third TID (TID2) that is not mapped to the second link (Link2) through the second link (Link2). At this time, the non-AP multilink device transmits an MPDU corresponding to the third TID (TID2) that is not mapped to the second link (Link2) through the second link (Link2) when a pre-specified condition is satisfied. Specifically, since 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 the 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 through the first link with the end of transmission through the second link, there is a shortage of traffic to be transmitted through the second link (Link2), so the non-AP multilink device can transmit an MPDU corresponding to the 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 a plurality of links, the multilink device can transmit a frame corresponding to a TID that is not mapped to the selected link through the selected link. Specifically, when a multilink device selects a link to be used for transmission from among a plurality of links, the multilink device can transmit a frame corresponding to a TID that is mapped to a link that is not selected from among the plurality of links through the selected link. Specifically, such an embodiment may be applied to the embodiment described with reference to FIG. 13.

[0154] In these embodiments, a problem may arise as to which link the multilink device should 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 a TID not mapped to a link on 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 a first TID (TID0) on the first link (Link1) and an ACK for a frame corresponding to a third TID (TID2) transmitted on the first link (Link1). In addition, the AP multilink device may transmit an ACK for a frame corresponding to a second TID (TID1) on the second link (Link2) and an ACK for a frame corresponding to a third TID (TID2) transmitted on the second link (Link2). In these embodiments, the multilink device transmits a response to the frame on the link on which the frame was received, so that the implementation complexity may be reduced.

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

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

[0157] 17 illustrates an operation of a station performing UL MU transmission 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. In this case, the multilink device can determine whether to transmit the MPDU corresponding to the TID not mapped to the link on the link based on the comparison result. Specifically, when 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 on the link. For example, when 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 on the link.

[0159] In yet another specific embodiment, when 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 on the link. For example, when 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 on the link. This allows the multilink device to have an opportunity to transmit traffic that is difficult to obtain a transmission opportunity due to its low priority.

[0160] A multilink device may transmit an MPDU corresponding to a TID not mapped to a link through the link only when 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, an MPDU corresponding to a TID mapped to a link and an MPDU corresponding to a TID not mapped to the link may be transmitted together as follows. An A-MPDU (aggregate-MPDU) transmitted through any one of the links may be an aggregate of an MPDU corresponding to a TID mapped to the link and an MPDU corresponding to a TID not mapped to the link. Also, a PPDU transmitted through any one of the links 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 at the same time. Such transmission or a series of processes for transmission is called an uplink (UL) multi-user (MU) operation or UL MU transmission. For UL MU transmission, an operation of triggering transmission of multiple stations may precede the UL MU transmission.

[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. Furthermore, the TB PPDU can represent a PPDU that supports multiple stations to transmit simultaneously. Multiple stations receive a frame that triggers UL MU transmission, and the multiple stations can perform UL MU transmission based on the received frame. The AP can transmit a frame that triggers UL MU transmission to multiple stations. Furthermore, the frame that triggers UL MU transmission can indicate a resource unit (RU) assigned to each of the multiple stations in the UL MU transmission in which the UL MU transmission is performed. The station can transmit the TB PPDU in the RU assigned to the station. Furthermore, the frame that triggers UL MU transmission can be a trigger frame or a frame including trigger information. The frame including trigger information can include trigger information in a MAC header. Specifically, the frame including trigger information can include trigger information in an A-Control field. Specifically, the trigger information may be a triggered response scheduling (TRS) control field. Also, the UL MU transmission may be transmitted in the above-mentioned TB PPDU. Also, 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 called response length information. The response length information may indicate the length of the PPDU including the UL MU transmission. The 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 of the L-SIG field of the PPDU including the UL MU transmission. For example, the station may determine the value of the Length field of 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 of the response length information, the station may determine the length of the TB PPDU according to the response length information. Specifically, the station may insert padding into the TB PPDU. For example, if there are empty bits in the TB PPDU after the station inserts all the traffic in the buffer into the TB PPDU, the station may insert padding into the empty bits. This allows the station to meet 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 the station performs a UL MU transmission, the station transmits according to the length indicated by the frame triggering the UL MU transmission. Furthermore, all stations performing a UL MU transmission may transmit a TB PPDU of the same length. Furthermore, the response to the UL MU transmission may be an immediate response to the UL MU transmission. Therefore, the interval between the UL MU transmission and the response to the UL MU transmission may be SIFS.

[0165] Referring to FIG. 17, the AP transmits a trigger frame to the first station (STA1) and the second station (STA2). Each of the first station (STA1) and the second station (STA2) transmits a TB PPDU in an RU indicated by the trigger frame as being assigned to each of the first station (STA1) and the second station (STA2). At this time, the length of the TB PPDU transmitted by each of the first station (STA1) and the second station (STA2) is determined by response length information indicated by the trigger frame. The length of the TB PPDU transmitted by the first station (STA1) and the second station (STA2) is 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 each of the first station (STA1) and the second station (STA2). In this way, a restriction on the transmission end time may be applied even when the station transmits the 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 a UL MU, the station can transmit a frame corresponding to a TID that is not mapped to a link that transmits the UL MU. Specifically, when a station transmits a UL MU, the station can transmit both a frame that is mapped to a link that transmits the UL MU and a frame corresponding to a TID that is not mapped to the link. In FIG. 18, the station transmits a TB PPDU through a first link (Link1). At this time, the uplink of the first link (Link1) is mapped to AC_VI and AC_BE. At this time, the station can transmit a TB PPDU including a data frame or PDSU corresponding to AC_VI and AC_BE and padding, as shown in FIG. 18(b). However, in this embodiment, if the length of the padding is excessively long, the transmission efficiency may be reduced. In addition, for a station that transmits a trigger frame, for example, an AP, it is not possible to accurately know the traffic stored in the buffers of multiple stations that transmit UL MU, and the length of the padding included in the TB PPDU is likely to be large. Therefore, the station can further include in the TB PPDU a data frame or PSDU corresponding to another AC not mapped to the first link (Link1), ie, AC_VO, as shown in FIG. 18(c).

[0167] As described above, the station can compare the priority of the TIDs mapped to the link with the priority of the TIDs not mapped to the link, and based on the comparison result, determine whether to transmit a frame corresponding to a TID not mapped to the link on the 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, the station cannot transmit a PPDU including only a frame corresponding to a TID not mapped to the link, but can transmit both a frame corresponding to a TID mapped to the link and a frame corresponding to a TID not mapped to the link. In FIG. 18, the embodiments of the present invention are described using ACs, but as described above, these embodiments may also be applied to the case where a link and a TID or TSID are mapped 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 specifies a rule for aggregating MPDUs corresponding to different TIDs into one A-MPDU. Therefore, MPDUs aggregated according to the multi-TID aggregation rule may not follow the mapping between links and TIDs. Specifically, when a station aggregates MPDUs according to the multi-TID aggregation rule, it may transmit an MPDU corresponding to a TID that is not mapped to a link on the 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 TXOP is included in the A-MPDU to be aggregated.

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

[0176] In yet another specific embodiment, the station can transmit a TID that is not mapped to a link on the link according to the PPDU format. Specifically, when the 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 can be a DL HE MU PPDU or an EHT PPDU transmitted to multiple users. The station can also 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 a frame corresponding to a TID that is 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 the trigger frame indicates a specific AC, and even if the TID is not mapped to a link, the station can transmit a frame corresponding to the TID using the TB PPDU if the TID has the same priority as or a higher priority than the priority of the specific AC. In yet another specific embodiment, if the Preferred AC subfield of the trigger frame indicates a specific AC, and even if the TID is not mapped to a link, the station can transmit a frame corresponding to the TID using the TB PPDU if the TID has a lower priority than the priority of the specific AC. This embodiment may be applied when there is no frame corresponding to a higher priority than the priority of the specific AC in the transmission buffer. Also, as described above, within the range of the allowable length of the TB PPDU, the station can transmit a frame corresponding to the TID using the TB PPDU even if the TID is not mapped to a link. In this case, the number of TIDs of frames aggregated into the 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 the A-MPDU.

[0178] FIG. 19 illustrates an element that signals 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 FIG. 16 to FIG. 18. This is because receiving a frame corresponding to a TID other than the TID mapped to the link may lead to a request for additional operations from the station. Specifically, it may signal whether 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. When 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, when 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 follow the link-TID mapping can be 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 follow the link-TID mapping. Specifically, when the information indicating whether frame transmission that does not follow the link-TID mapping can be 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 follow the link-TID mapping when a constraint on the transmission end time is applied.

[0181] In addition, the information indicating whether frame transmission that does not follow the link-to-TID mapping can be supported or tolerated can indicate whether the station supports or tolerates transmission in accordance with a restriction on the transmission end time, where the tolerance can indicate whether the transmission can be received.

[0182] Also, the 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, the 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, the 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. Also, the station may signal the maximum number of TIDs that the station can receive.

[0183] In the above embodiment, a Capabilities element or an Operation element may be used for signaling. A station may use a Capabilities element or an Operation element to signal whether the station supports or tolerates frame transmission that does not follow the link-to-TID mapping. A station may also use a Capabilities element or an 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] FIG. 19(a) illustrates a Capabilities element according to one embodiment of the present invention, and FIG. 19(b) illustrates 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 may 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 may indicate the maximum number of TIDs that an AP can receive.

[0185] The above-mentioned signaling indicating whether to support and signaling indicating whether to allow may be included in the same type of element. Also, the signaling indicating whether to support frame transmission not following the link-TID mapping and the signaling indicating whether to allow frame transmission not following the link-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 not following the link-TID mapping. Also, when an AP transmits the element, the subfield of the element may indicate whether to allow frame transmission not following the link-TID mapping.

[0186] When a restriction on the transmission end time 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 in a transmit opportunity (TXOP) including the frame or PPDU. The maximum number of TIDs that a station can collect may be determined for each PPDU format. When information indicating the maximum number of TIDs that a station can collect 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 collect 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 in which the frame or PPDU is included.

[0187] Specifically, the frame that triggers the UL MU transmission may include information indicating whether frame transmission that does not follow the link-TID mapping is permitted. When the station transmits a response to the frame that triggers the UL MU transmission, the station may 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-TID mapping is permitted. In a specific embodiment, the information indicating whether frame transmission that does not follow the link-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-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 a 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. In addition, 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 information indicating the maximum number of TIDs that a station can collect. The above-mentioned Common Info field includes information that is commonly applied to all stations or TB PPDUs that respond to the trigger frame. The User Info field includes information that is applied to the station that responds with the RU indicated by the User Info field or the TB PPDU that is 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 according to 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 the station intends to transmit traffic with a relatively high priority, the length of the AIFS may be relatively short. Also, when the 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 to determine the AC, TID, or priority that the station applies may be an issue.

[0191] When a station performs channel access to transmit a trigger frame, the station may perform channel access based on an AC, TID, or priority corresponding to a frame transmitted in response to the trigger frame and a mapping between a link and a TID. Specifically, when a station performs channel access to transmit a trigger frame, the station may perform channel access based on an AC corresponding to a frame transmitted in response to the trigger frame and a mapping between a link and a TID. At this time, the mapping between a link and a TID may be set between a sender of the trigger frame and a receiver of the trigger frame. In a specific embodiment, the mapping between a link and a TID may be a mapping between a link in a direction from a receiver of the trigger frame to a sender of the trigger frame and a TID. When a station performs channel access to transmit a trigger frame, the station may apply a defined TID or AC to a mapping between a link in a direction from a receiver of the trigger frame to a sender of the trigger frame and a TID. When a station performs channel access to transmit a trigger frame, the station may not apply an undefined TID or AC to a mapping between a link in a direction from a receiver of the trigger frame to a sender of the trigger frame and a TID. When a station performs channel access to transmit a trigger frame, the station can apply a determined TID or AC 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. Also, when there are multiple receivers of the trigger frame, the mapping of links and TIDs may be a mapping of links and TIDs from multiple receivers to the sender. These embodiments may be applied when a PPDU including a frame triggering a UL MU transmission includes only a frame triggering a UL MU transmission. Also, these embodiments may be applied only when a PPDU including a frame triggering a UL MU transmission does not include a QoS data frame.

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

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

[0194] In FIG. 20, the AP multilink device includes a first AP (AP1). Also, the first non-AP multilink device (Non-AP MLD 1) includes a first station (STA1). Also, the 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 the 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 a frame corresponding to a TID that is not mapped to a link on the link. In this way, when the station does not perform a contention procedure to obtain a TXOP, the station can transmit regardless of the mapping between the link and the TID. Also, when the station obtains a TXOP through a contention procedure, the station can transmit based on the mapping between the link and the TID. For example, when the station does not obtain a TXOP through a contention procedure, the station can transmit a frame corresponding to a TID that is not mapped to a link on the link. When the station obtains a TXOP through a contention procedure, the station can transmit only a frame corresponding to a TID that is mapped to a link on the link.

[0197] FIG. 21 illustrates the operation of a multilink device transmitting on multiple links according to an embodiment of the present invention.

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

[0199] Additionally, limitations may be applied to the bandwidth used by a STR-limiting multilink device or a multilink device communicating with a STR-limiting multilink device, and in certain circumstances, a STR-limiting multilink device or a multilink device communicating with a STR-limiting multilink device may use less than a certain amount of bandwidth.

[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 position 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 channel 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 FIG. 21, when a second station (STA2) is transmitting, a 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 is a channel restricted by the first link (Link1).

[0202] The multilink device can independently determine whether the restricted channel is used. In another specific embodiment, the use of the restricted channel may be specifically indicated. For example, a frame triggering a UL MU transmission may assign a restricted channel. Also, 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 an operation of the multilink device according to the embodiment of the present invention for setting the NAV.

[0204] As described above, transmission may fail due to internal leakage that occurs when transmission and reception are performed simultaneously on multiple adjacent links. In FIG. 22, while a multilink device is receiving on a first link, it also transmits on a second link. Due to the transmission on the second link, the multilink device may fail to receive on the first link. If a station operating on the second link determines that the channel of the second link is idle, the station accesses the channel and transmits. A station operating on the first link (Link1) sets a network allocation vector (NAV) based on a frame or PPDU transmitted on the first link (Link1). A station operating on the first link (Link1) may determine that the channel is busy based on the NAV while another station is transmitting on the first link (Link1). In this way, if a frame or PPDU transmitted on the first link can set the NAV on the second link, the probability of transmission failing due to internal leakage can be reduced. This will be described with reference to FIG. 23 to FIG. 26.

[0205] FIG. 23 shows an 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 a TXOP Duration field of a signaling field of a PPDU. In this case, the signaling field may be a HE-SIG-A field. Also, the signaling field may be a U-SIG field. Also, the duration information may be a value indicated by a Duration / ID field of a MAC header. The TXOP Duration field and the Duration / ID field indicate a TXOP. In yet another specific embodiment, the duration information may be a value indicated by a Length field of an L-SIG field of a PPDU. The Length field indicates a length from after the end point 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 of each link based on the shared duration information. For example, a station included in the multilink device can set the 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 the 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 an intra-BSS PPDU.

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

[0209] In yet another specific embodiment, a plurality of stations included in the multilink device can use the inter-link NAV. Specifically, a station included in the multilink device can perform channel access based on the inter-link NAV, which is a NAV set based on a frame or PPDU exchanged by another station included in the same multilink device. For example, the multilink device operates on a first link and a second link, and a station operating on the second link among the stations of the multilink device can set the inter-link NAV based on a PPDU or frame transmitted on the first link. At this time, 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. At this time, the multilink device that sets the inter-link NAV can determine whether to perform channel access or transmission based on the inter-link NAV on multiple links or all links on which the multilink device operates.

[0210] In addition, the station can access the channel based on the basic NAV in addition to the intra-BSS NAV. The basic NAV may be a NAV set by an inter-BSS frame or an inter-BSS PPDU. When the station cannot determine whether a received frame is an inter-BSS frame or an intra-BSS frame, or cannot determine 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 the inter-link NAV is set, even if the set NAV is reset by the transmission of another link, the NAV value set by the transmission within the link may be maintained as it is. For example, the multilink device operates on the first link and the second link, and among the stations of the multilink device, a station operating on the second link may set the NAV based on the PPDU or frame transmitted on the second link. After that, after the station sets the NAV based on the PPDU or frame transmitted on the first link, when the TXOP expires on the first link and the NAV is reset, the NAV may be reset to the NAV set for the transmission of the second link. When the inter-link NAV is operated, the multilink device may maintain the NAV set for the transmission of the second link even if the TXOP expires on the first link and the inter-link NAV is reset. Therefore, the multilink device can operate stably due to the inter-link NAV.

[0212] In the above 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. Or, in the above 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 performing channel access, performing transmission, 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 of the multilink device to the physical layer of another station of the multilink device may be used. Or, specifically, the MAC layer of one station of the multilink device may be connected to the MAC layer of another station of the multilink device.

[0213] Also, when any one station of the multilink device starts receiving a PPDU, the other station of the multilink device may suspend channel access. As described above, the other station may suspend 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 when channel access is performed and transmission is performed until the duration information is obtained. Therefore, as described above, when any one station of the multilink device starts receiving a PPDU, the other station of the multilink device may suspend channel access. Also, when the intended recipient of the PPDU received by any one station or the frame contained in the PPDU is not the corresponding station, the other station may resume the suspended channel access. This will be specifically described 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 of a multi-link device can suspend channel access or transmission according to a PPDU received by another station of the multi-link device. At this time, if the other station is not the recipient of the PPDU received by the other station 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 the channel access or transmission suspension. 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 the other 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] Also, if the other station is not the intended recipient of the PPDU received by the other station, the station may resume channel access or transmission. If the other station is the intended recipient of the PPDU received by the other station, the station may continue channel access or transmission suspension. If the other station is the intended recipient of the received PPDU, it may be the case 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 include the case 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 may determine that the other station is the intended recipient of the PPDU received by the other station.

[0218] Also, 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 frames contained in the PPDU received by the other station.

[0220] In the above 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 the other link. 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-mentioned 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, when the received PPDU is an EHT PPDU, the other station may sequentially decode the L-SIG, U-SIG, EHT-SIG, and MAC header. Also, when the received PPDU is an HE SU PPDU or an HE TB PPDU, the other station may sequentially decode the L-SIG, HE-SIG-A, and MAC header. Also, when 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, when 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 or not the intended recipient is a value determined based on the AID or MAC address of the station. The identifier used to determine whether or not the intended recipient is a value indicating a station.

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

[0224] When a station transmits a response to a frame triggering 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 triggering 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 triggering UL MU transmission transmitted by a multi-link 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 has 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 and inter-link NAV. Also, when a station receives a trigger frame from a station that has 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 and inter-link NAV.

[0226] In the above embodiments, the station not taking the NAV into consideration 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, so that the AP multilink device can increase the network efficiency.

[0228] In the embodiment of FIG. 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 a 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, etc. Also, 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 embodied 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. The features, structures, effects, etc. exemplified in each embodiment can be combined or modified in other embodiments by a person having ordinary knowledge in the field to which the embodiment belongs. Therefore, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention.

[0231] Although the above description focuses on the embodiments, these are merely illustrative and do not limit the present invention. Those skilled in the art will understand that various modifications and applications not exemplified above are possible without departing from 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 interpreted as being included in the scope of the present invention defined in the appended claims. [Explanation of symbols]

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

Claims

1. A multi-link device using multiple links, Transmitting and receiving unit and A processor is included. The processor, A multi-link device that, when the multi-link device transmits multiple PPDUs simultaneously on multiple links using the transceiver unit, determines a transmission end time of the multiple PPDUs based on whether the multi-link device transmits a frame requesting ACK.

2. The processor, The multi-link device of claim 1 , wherein when the multi-link device transmits a plurality of PPDUs simultaneously through a plurality of links, the multi-link device aligns ends of a plurality of PPDUs that request ACK among the plurality of PPDUs.

3. The processor, The multi-link device of claim 1, wherein when the multi-link device transmits multiple PPDUs simultaneously on multiple links, the end of a PPDU among the multiple PPDUs that includes only frames that do not request ACK is not aligned with the end of a PPDU among the multiple PPDUs that includes a frame that requests ACK.

4. The processor, The multi-link device of claim 3, wherein when the multi-link device transmits multiple PPDUs simultaneously on multiple links, the multiple PPDUs are transmitted such that the end of a PPDU among the multiple PPDUs that includes only frames that do not request ACK is not delayed behind the end of a PPDU among the multiple PPDUs that includes a frame that requests ACK.

5. 2. The multi-link device of claim 1, wherein whether the frame requesting ACK is a frame requesting ACK or not is determined based on an ACK policy.

6. 6. The multi-link device of claim 5, wherein the frame requesting the ACK is a data frame.

7. the multilink device is an AP multilink device, The processor, The multilink device according to claim 1 , further comprising: a transceiver unit configured to transmit the plurality of PPDUs to a non-AP multilink device.

8. The multi-link device of claim 1 , wherein the multi-link device that receives the plurality of PPDUs is unable to receive the PPDUs on the other links when transmitting the PPDUs on any one of the links.

9. A multi-link device using multiple links, Transmitting and receiving unit and A processor is included. The processor, the multi-link device receives a plurality of PPDUs simultaneously over a plurality of links using the transceiver unit; A multi-link apparatus, wherein a transmission end time of the plurality of PPDUs is determined based on whether a frame requesting ACK is transmitted in the plurality of PPDUs.

10. The multi-link apparatus of claim 9, wherein ends of a plurality of PPDUs requesting ACK among the plurality of PPDUs are aligned.

11. The multi-link device of claim 9, wherein an end of a PPDU including only frames not requesting an ACK among the plurality of PPDUs is not aligned with an end of a PPDU including a frame requesting an ACK among the plurality of PPDUs.

12. The multi-link apparatus of claim 11, wherein an end of a PPDU including only frames not requesting an ACK among the plurality of PPDUs is not later than an end of a PPDU including a frame requesting an ACK among the plurality of PPDUs.

13. 10. The multi-link device of claim 9, wherein whether the frame requesting ACK is a frame requesting ACK or not is determined based on an ACK policy.

14. 14. The multi-link device of claim 13, wherein the frame requesting the ACK is a data frame.

15. The multilink device is a non-AP multilink device, The processor, The multilink device of claim 9 , further comprising: a receiver for transmitting the plurality of PPDUs from an AP multilink device.

16. 10. The multi-link device according to claim 9, wherein when transmitting through any one of the links, receiving through the other links is not possible.

17. The processor, accessing a channel in the plurality of links by a channel access method using a back-off counter, the back-off counter having an initial value set by an acquired random number, decrementing by one when the channel being accessed during a slot time is idle, and allowing the terminal to access the channel when the back-off counter value is 0; 17. The multilink device according to claim 16, wherein even if a backoff counter reaches 0 during channel access of any one of the plurality of links, no transmission is performed on the any one of the links.

18. The processor, 18. The multi-link device according to claim 17, wherein the back-off counter value is maintained when no transmission is performed on any one of the links.

19. 1. A method of operating a multi-link device using multiple links, comprising: receiving a plurality of PPDUs simultaneously via a plurality of links using the transceiver unit; An operating method in which a transmission end time of the plurality of PPDUs is determined based on whether a frame requesting ACK is transmitted in the plurality of PPDUs.

20. The method of claim 19, wherein ends of a plurality of PPDUs that request ACK among the plurality of PPDUs are aligned.

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