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

Abstract

The present invention provides a multilink device that uses multiple links. [Solution] The multilink device includes a transceiver and a processor. When the multilink device transmits multiple PPDUs simultaneously over multiple links using the transceiver and the processor, the processor determines the end time of transmission for the multiple PPDUs based on whether or not the multilink device transmits a frame requesting an ACK.

Description

Technical Field

[0001] The present invention relates to a wireless communication method using multiple links and a wireless communication terminal using the same.

Background Art

[0002] Recently, with the spread of mobile devices, Wireless LAN (Wireless Local Area Network) technology that can provide fast wireless Internet services to them has been in the spotlight. Wireless LAN technology is a technology that enables mobile devices such as smartphones, smart pads, laptop PCs, portable multimedia players, and embedded devices to be wirelessly connected to the Internet in homes, enterprises, or specific service-providing areas based on wireless communication technology at short distances.

[0003] Since IEEE (Institute of Electrical and Electronics Engineers) 802.11 supported the initial wireless LAN technology using the 2.4 GHz frequency, various technology standards have been put into practical use or are under development. First, IEEE 802.11b uses the frequency of the 2.4 GHz band and supports a communication speed of up to 11 Mbps. IEEE 802.11a, which was commercialized after IEEE 802.11b, uses the frequency of the 5 GHz band instead of the 2.4 GHz band, reducing the impact on interference compared to the rather congested 2.4 GHz band frequency, and using OFDM technology to improve the communication speed up to 54 Mbps. However, IEEE 802.11a has the disadvantage of a shorter communication distance compared to IEEE 802.11b. And IEEE 802.11g uses the same 2.4 GHz band frequency as IEEE 802.11b to implement a maximum communication speed of 54 Mbps and satisfies backward compatibility, attracting considerable attention, but it is also superior to IEEE 802.11a in terms of communication distance.

[0004] Furthermore, IEEE 802.11n is a technical standard established to overcome the limitations in communication speed that had been pointed out as a vulnerability in wireless LANs. The purpose of IEEE 802.11n is to increase network speed and reliability and extend the operating range of wireless networks. Specifically, IEEE 802.11n supports high throughput (HT) with a data processing speed of up to 540 Mbps or more, and is based on MIMO (Multiple Inputs and Multiple Outputs) technology, which uses multiple antennas at both the transmitter and receiver ends to minimize transmission errors and optimize data speed. In addition, this standard uses a coding method that transmits multiple duplicate copies to improve data reliability.

[0005] As the proliferation of wireless LANs accelerates and the applications using them diversify, there is a growing need for new wireless LAN systems that can support very high throughput (VHT) higher than the data processing speed supported by IEEE 802.11n. Among these, IEEE 802.11ac supports a wide bandwidth (80MHz to 160MHz) at the 5GHz frequency. Although the IEEE 802.11ac standard is defined only in the 5GHz band, early 11ac chipsets are expected to support operation in the 2.4GHz band for backward compatibility with older 2.4GHz band products. Theoretically, this standard allows for a minimum wireless LAN speed of 1Gbps and a maximum single-link speed of 500Mbps. This is achieved by extending the wireless interface concepts accepted in 802.11n, including wider radio frequency bandwidth (up to 160MHz), more MIMO spatial streams (up to 8), multi-user MIMO, and high-density modulation (up to 256QAM). Another method for transmitting data using the 60GHz band instead of the conventional 24GHz / 5GHz band is IEEE 802.11ad. IEEE 802.11ad is a transmission standard that uses beamforming technology to provide speeds of up to 7Gbps, making it suitable for streaming large amounts of data and high-bitrate video such as uncompressed HD video. However, the 60GHz frequency band has the disadvantage of being difficult to pass through obstacles, limiting its use to devices in short-range spaces.

[0006] Meanwhile, the IEEE 802.11ax (High Efficiency WLAN, HEW) standard has been developed and is nearing completion as a wireless LAN standard for 802.11ac and 802.11ad and beyond, to provide highly efficient and high-performance wireless LAN communication technology in high-density environments where access points (APs) and terminals are densely packed. In an 802.11ax-based wireless LAN environment, it is necessary to provide highly frequency-efficient communication indoors and outdoors in the presence of high-density stations and APs (Access Points), and various technologies have been developed to realize this.

[0007] Furthermore, in order to support new multimedia applications such as high-definition video and real-time games, development has begun on a new wireless LAN standard to increase the maximum transmission speed. The 7th generation wireless LAN standard, IEEE 802.11be (Extremely High Throughput, EHT), is being developed with the goal of supporting a maximum transmission rate of 30 Gbps in the 2.4 / 5 / 6 GHz band through wider bandwidth, increased spatial streams, and multiple AP coordination. [Overview of the project] [Problems that the invention aims to solve]

[0008] One embodiment of the present invention aims to provide a wireless communication method using multilink and a wireless communication terminal using the same. [Means for solving the problem]

[0009] In one embodiment of the present invention, a multilink device using multiple links includes a transceiver unit and a processor. When the multilink device transmits multiple PPDUs simultaneously over multiple links using the transceiver unit, the processor determines the end time of transmission for the multiple PPDUs based on whether or not the multilink device transmits a frame requesting an ACK.

[0010] When the multilink device transmits multiple PPDUs simultaneously over multiple links, the processor can align the ends of the multiple PPDUs that request an ACK.

[0011] When the multilink device transmits multiple PPDUs simultaneously over multiple links, the processor does not need to align the end of a PPDU containing only frames that do not request an ACK with the end of a PPDU containing frames that request an ACK.

[0012] Specifically, when the multilink device transmits multiple PPDUs simultaneously over multiple links, the processor transmits the multiple PPDUs such that the termination of a PPDU containing only frames that do not request an ACK is delayed compared to the termination of a PPDU containing frames that do request an ACK.

[0013] The frame requesting the aforementioned ACK may be determined based on the ACK policy to determine whether or not it is a frame requesting an ACK.

[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] The multilink device that receives the aforementioned multiple PPDUs may be unable to receive on other links when transmitting on one link.

[0017] According to an embodiment of the present invention, a multilink device using multiple links includes a transceiver unit and a processor. The processor receives multiple PPDUs simultaneously on multiple links using the transceiver unit. The end time of transmission for the multiple PPDUs is determined based on whether or not a frame requesting an ACK is transmitted for the multiple PPDUs.

[0018] Of the aforementioned multiple PPDUs, the ends of the multiple PPDUs requesting ACK may be aligned.

[0019] The end of one of the aforementioned PPDUs, which contains only frames that do not request an ACK, does not need to be aligned with the end of one of the aforementioned PPDUs, which contains frames that request an ACK.

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

[0021] Based on an ACK policy, it may be determined whether a frame requests ACK or not for the frame that requests ACK.

[0022] A frame that requests ACK may be a data frame.

[0023] The multi-link device is a non-AP multi-link device, and the processor can transmit the plurality of PPDUs from an AP multi-link device using the receiving unit.

[0024] When transmitting on any one link, it may be impossible to receive on other links.

[0025] The processor can access the channel by a channel access method using a backoff counter on the plurality of links. At this time, the initial value of the backoff counter is set by an acquired random number, and it decreases by 1 when the channel accessed during the slot time is idle. When the value of the backoff counter is 0, access of the terminal to the channel may be permitted. Even when the backoff counter reaches 0 in the channel access of any one of the plurality of links, the processor may not perform transmission on any one of the links.

[0026] When not performing transmission on any one of the links, the processor can maintain the value of the backoff counter.

[0027] According to an embodiment of the present invention, a method for operating a multi-link device using a plurality of links includes a step of the multi-link device receiving a plurality of PPDUs simultaneously via a plurality of links using the transceiver. The end time of transmission of the plurality of PPDUs is determined 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 an ACK may be aligned.

Advantages of the Invention

[0029] An embodiment of the present invention provides a wireless communication method using multi-links efficiently and a wireless communication terminal using the same.

Brief Description of the Drawings

[0030] [Figure 1] It is a diagram showing a wireless LAN system according to an embodiment of the present invention. [Figure 2] It is a diagram showing a wireless LAN system according to another embodiment of the present invention. [Figure 3] It is a diagram showing the configuration of a station according to an embodiment of the present invention. [Figure 4] It is a diagram showing the configuration of an access point according to an embodiment of the present invention. [Figure 5] It is a diagram schematically showing a process in which a STA sets a link with an AP. [Figure 6] It is a diagram showing the CSMA (Carrier Sense Multiple Access) / CA (Collision Avoidance) method used in wireless LAN communication. [Figure 7] An example of PPDU (PLCP Protocol Data Unit) formats for various standard generations is shown. [Figure 8] An example of various EHT (Extremely High Throughput) PPDU (Physical Protocol Data Unit) formats according to an embodiment of the present invention and a method for instructing the same is shown. [Figure 9] This shows a multi-link device according to an embodiment of the present invention. [Figure 10] An embodiment of the present invention illustrates a case in which transmissions from different links occur simultaneously in multilink operation. [Figure 11] This demonstrates the operation of a multilink device according to an embodiment of the present invention, which simultaneously terminates transmission on multiple links. [Figure 12] This embodiment of the present invention demonstrates the operation in which a multilink device, when transmitting over multiple links, terminates transmission on one of the links first. [Figure 13] This indicates that when a multilink device according to an embodiment of the present invention transmits on one link, the multilink device will postpone transmission on the other links. [Figure 14] This embodiment of the present invention demonstrates the operation in which a multilink device, when transmitting over multiple links, terminates transmission on one of the links first. [Figure 15] This describes an operation in which a multilink device according to yet another embodiment of the present invention terminates transmission on one of the links first when transmitting on multiple links. [Figure 16] This demonstrates that a multilink device according to an embodiment of the present invention operates using a mapping between links and TIDs. [Figure 17] This demonstrates the operation of a station according to an embodiment of the present invention that performs UL MU transmission. [Figure 18] This demonstrates that a multilink device according to an embodiment of the present invention aggregates multiple TIDs. [Figure 19] This shows an element that signals information regarding the mapping between a link and a TID according to an embodiment of the present invention. [Figure 20] This demonstrates that a station according to an embodiment of the present invention accesses a channel to transmit a trigger frame. [Figure 21] This embodiment of the present invention demonstrates the operation of a multilink device that transmits over multiple links. [Figure 22] This demonstrates the operation of a multilink device according to an embodiment of the present invention to set the NAV. [Figure 23] This example demonstrates the operation of a multilink device according to an embodiment of the present invention to set the NAV. [Figure 24] This embodiment of the present invention shows that a station in a multilink device resumes channel access or transmission after interrupting channel access or transmission due to a PPDU received by another station in the multilink device. [Figure 25] This invention describes a method by which a multilink device according to an embodiment of the present invention transmits a response to a trigger frame when NAV is set in the multilink device and a trigger frame is received. [Modes for carrying out the invention]

[0031] The terminology used herein has been selected to the greatest extent possible from currently widely used general terms, taking into account the function of the present invention; however, this may differ depending on the intent, conventions, or emergence of new technologies of the articulate persons in the relevant field. In addition, in certain cases, the applicant has arbitrarily selected some terms, and in such cases, the meaning of these terms will be described in the relevant section of the invention description. Therefore, it should be made clear that the terms used herein are not merely names of terms, but should be interpreted based on the substantive meaning of the terms and the content of this specification as a whole.

[0032] Throughout the specification, when one component is described as being "connected" to another, this includes not only cases where they are "directly connected," but also cases where they are "electrically connected" with other components in between. Furthermore, when a component is described as "containing" a particular component, this means, unless otherwise stated, that it may contain other components rather than excluding them. In addition, limitations such as "greater than or equal to" or "less than or equal to" a specific critical value may be appropriately replaced by "greater than" or "less than" depending on the embodiment.

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

[0034] Figure 1 shows a wireless LAN system according to one embodiment of the present invention.

[0035] A wireless LAN system includes one or more Basic Service Sets (BSS), where a BSS represents a set of devices that have successfully synchronized and can 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 Figure 1, the infrastructure BSS BSS1, BSS2 includes one or more stations STA1, STA2, STA3, STA4, STA5, access points AP-1, AP-2 which are stations that provide distribution services, and a distribution system DS that connects multiple access points AP-1, AP-2.

[0037] A Station (STA) is any device that includes Medium Access Control (MAC) and a Physical Layer interface to a wireless medium in accordance with the IEEE 802.11 standard, and in a broad sense includes not only non-AP stations but also all access points (APs). In this specification, "terminal" is used to refer to non-APs, APs, or both. A station for wireless communication includes a processor and a communication unit, and depending on the embodiment, further includes a user interface unit and a display unit, etc. The processor generates frames to be transmitted over the wireless network or processes frames received over the wireless network, and performs various other processing for controlling the station. The communication unit is functionally connected to the processor and sends and receives frames over the wireless network for the station. In this invention, "terminal" is used as a term that includes user equipment (UE).

[0038] An Access Point (AP) is an individual device that provides connectivity to a distribution system (DS) via a wireless medium for stations associated with it. In infrastructure BSS, communication between non-AP stations is generally conducted via APs, however, direct communication is possible between non-AP stations if a direct link is configured. In this invention, AP is used as a concept that includes PCP (Personal BSS Coordination Point), but in a broader sense, it includes all concepts such as central controllers, base stations (BS), node B, BTS (Base Transceiver System), or site controllers. In this invention, AP is also referred to as a base wireless communication terminal, but in a broader sense, base wireless communication terminal is used as a term that includes APs, base stations, eNBs (eNodeBs), and transmission points (TPs). Furthermore, base wireless communication terminals include various forms of wireless communication terminals that allocate and schedule communication medium resources in communication with multiple wireless communication terminals.

[0039] Multiple infrastructure BSSs are connected to each other via a distribution system DS. In this case, multiple BSSs connected via the distribution system are called an Extended Service Set (ESS).

[0040] Figure 2 shows an independent BSS, which is a wireless LAN system according to another embodiment of the present invention. In the embodiment of Figure 2, redundant explanations are omitted for parts that are the same as or corresponding to the embodiment of Figure 1.

[0041] As shown in Figure 2, BSS3 is an independent BSS and does not include APs, so all stations (STA6, STA7) are not connected to APs. 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 one another.

[0042] Figure 3 is a block diagram showing the configuration of station 100 according to one embodiment of the present invention. As shown, 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 incorporated into or externally mounted to the station 100. According to one 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 2.4GHz, 5GHz, 6GHz, and 60GHz. According to one embodiment, the station 100 may include a communication module using a frequency band of 7.125GHz or higher and a communication module using a frequency band of 7.125GHz or lower. Each communication module can perform wireless communication with an AP or external station based on the wireless LAN standard of the frequency band supported by the communication module. Depending on the performance and requirements of the station 100, the communication unit 120 may operate only one communication module at a time or operate multiple communication modules together simultaneously. When the station 100 includes multiple communication modules, each communication module may be provided in an independent form, or the multiple modules may be integrated as a single chip. In embodiments of the present invention, the communication unit 120 can represent an RF (Radio Frequency) communication module that processes RF signals.

[0044] Next, the user interface 140 includes various forms of input / output means provided in the station 100. In other words, 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. The user interface unit 140 also outputs based on instructions from the processor 110 using various output means.

[0045] Next, the display unit 150 outputs an image to the display screen. The display unit 150 outputs various display objects, such as content generated by the processor 110 or user interfaces based on control instructions from the processor 110. The memory 160 stores control programs used by the station 100 and various data associated with them. Such control programs include connection programs necessary for the station 100 to connect with APs or external stations.

[0046] The processor 110 of the present invention executes various instructions or programs and processes data within the station 100. The processor 110 also controls each unit of the station 100 and controls the transmission and reception of data between units. According to an embodiment of the present invention, the processor 110 executes a program for connection with the AP stored in the memory 160 and receives a communication setup message transmitted by the AP. The processor 110 also reads information regarding the priority conditions of the station 100 contained in the communication setup message and requests a connection to the AP based on the priority conditions of the station 100. The processor 110 of the present invention may refer to the main control unit of the station 100, or, depending on the embodiment, may refer to a control unit for individually controlling a part of the station 100's configuration, such as the communication unit 120. In other words, the processor 110 may be a modem or a modulator and / or demodulator that modulates and demodulates the wireless signals transmitted and received from the communication unit 120. The processor 110 controls various operations of wireless signal transmission and reception of the station 100 according to an embodiment of the present invention. A detailed embodiment relating to this will be described later.

[0047] The station 100 shown in Figure 3 is a block diagram according to one embodiment of the present invention, and the separately shown blocks represent logically distinguished elements of the device. Therefore, the above-mentioned elements of the device are mounted on one chip or multiple chips depending on the device design. For example, the processor 110 and the communication unit 120 may be integrated and implemented on a single chip, or they may be implemented on separate chips. Furthermore, in the 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] Figure 4 is a block diagram showing the configuration of AP200 according to one embodiment of the present invention. As shown, AP200 according to an embodiment of the present invention includes a processor 210, a communication unit 220, and a memory 260. In Figure 4, redundant explanations are omitted for parts of the AP200 configuration that are the same as or correspond to the configuration of station 100 in Figure 3.

[0049] Referring to Figure 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 Figure 3, the communication unit 220 of the AP 200 can also include a plurality of communication modules using different frequency bands. That is, the AP 200 according to an embodiment of the present invention can include two or more communication modules using different frequency bands, for example, 2.4 GHz, 5 GHz, 6 GHz, and 60 GHz. Preferably, the AP 200 can 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 can communicate wirelessly with the station based on the wireless LAN standard of the frequency band supported by the communication module. Depending on the performance and requirements of the AP 200, the communication unit 220 can operate only one communication module at a time or operate multiple communication modules together simultaneously. In an embodiment of the present invention, the communication unit 220 can represent an RF (Radio Frequency) communication module that processes RF signals.

[0050] Next, the memory 260 stores the control program used by the AP200 and various data associated with it. Such a control program includes a connection program that manages station connections. The processor 210 controls each unit of the AP200 and controls the transmission and reception of data between units. According to one embodiment of the present invention, the processor 210 executes the program for connecting with stations stored in the memory 260 and transmits a communication setting message to one or more stations. In this case, the communication setting message includes information regarding the connection priority conditions of each station. The processor 210 also performs connection settings in response to connection requests from stations. According to one embodiment, the processor 210 is a modem or modulation / demodulation unit that modulates and demodulates the wireless signals transmitted and received from the communication unit 220. The processor 210 controls various operations of wireless signal transmission and reception of the AP200 according to the embodiment of the present invention. A detailed embodiment relating thereto will be described later.

[0051] Figure 5 is a schematic diagram illustrating the process by which STA establishes a link with AP.

[0052] Referring to Figure 5, the link between STA100 and AP200 is established through three main steps: scanning, authentication, and association. First, the scanning step is the step in which STA100 obtains connection information for the BSS operated by AP200. There are two methods for performing scanning: passive scanning, which obtains information using only the beacon message S101 that AP200 periodically transmits, and active scanning, in which STA100 transmits a probe request S103 to the AP, receives a probe response S105 from the AP, and obtains connection information.

[0053] In the scanning step, STA100, having successfully received wireless connection information, transmits an authentication request (S107a), receives an authentication response from AP200 (S107b), and performs the authentication step. After the authentication step is performed, STA100 transmits an association request (S109a), receives an association response from AP200 (S109b), and performs the association step. In this specification, "association" basically means wireless coupling, but the present invention is not limited to this, and in a broad sense, coupling includes both wireless and wired coupling.

[0054] On the other hand, an additional 802.1X-based authentication step S111 and an IP address acquisition step S113 via DHCP are performed. In Figure 5, Server 300 is a server that processes authentication between STA100 and the 802.1X-based system, and may be physically connected to AP200 or exist as a separate server.

[0055] Figure 6 shows the CSMA (Carrier Sense Multiple Access) / CA (Collision Avoidance) method used in wireless LAN communication.

[0056] A terminal performing wireless LAN communication checks whether a channel is busy or not by performing carrier sensing before transmitting data. If a wireless signal above a certain strength is detected, the channel is determined to be busy, and the terminal delays access to that channel. This process is called Clear Channel Assessment (CCA), and the level at which the detection of the signal is determined is called the CCA threshold. If a wireless signal above the CCA threshold is received by the terminal and the terminal is the recipient, the terminal processes the received wireless signal. On the other hand, if no wireless signal is detected from the channel, or if a wireless signal below the CCA threshold is detected, the channel is determined to be idle.

[0057] If a channel is determined to be idle, each terminal with data to transmit performs a backoff procedure after a time period determined by the status of each terminal, such as an IFS (Inter Frame Space), AIFS (Arbitration IFS), PIFS (PCF IFS), etc. In this embodiment, the AIFS is used as a replacement for the conventional DIFS (DCF IFS). Each terminal waits, decreasing a slot time equal to a random number determined for that terminal during the interval of idle state of the channel, and the terminal that has exhausted all of its slot time attempts to access the channel. The period in which each terminal performs this backoff procedure is called the competition window period. At this time, the random number can be called the backoff counter. That is, the initial value of the backoff counter is set by an integer, which is a random number acquired by the terminal. If a terminal senses that a channel is idle during the slot time, the terminal can decrease the backoff counter by 1. Also, when the backoff counter reaches 0, the terminal may be allowed to access the channel. Therefore, terminal transmission may be permitted when the channel is idle during the AIFS time and the backoff counter slot time.

[0058] If a specific terminal successfully accesses the channel, it transmits data through the channel. However, if a terminal attempting access collides with another terminal, the colliding terminals are each assigned a new random number and perform a further backoff procedure. In one embodiment, the random number newly assigned to each terminal is determined within a range twice the range (competition window, CW) of the random number previously assigned to that terminal (2*CW). Meanwhile, each terminal attempts access again in the next competition window interval by performing a further backoff procedure, but this time, each terminal performs the backoff procedure from the slot time remaining in the previous competition window interval. In this way, each terminal performing wireless LAN communication can avoid collisions with each other for a specific channel.

[0059] <Examples of various PPDU formats>

[0060] Figure 7 shows examples of various standard generational PPDU (PLCP Protocol Data Unit) formats. More specifically, Figure 7(a) shows one example of a legacy PPDU format based on 802.11a / g, Figure 7(b) shows one example of an HE PPDU format based on 802.11ax, and Figure 7(c) shows one example of a non-legacy PPDU (i.e., EHT PPDU) format based on 802.11be. Figure 7(d) shows the detailed field configuration of L-SIG and RL-SIG commonly used in the aforementioned PPDU formats.

[0061] Referring to Figure 7(a), the legacy PPDU preamble includes L-STF (Legacy Short Training field), L-LTF (Legacy Long Training field), and L-SIG (Legacy Signal field). In embodiments of the present invention, the L-STF, L-LTF, and L-SIG can be referred to as the legacy preamble.

[0062] Referring to Figure 7(b), the HE PPDU preamble further includes RL-SIG (Repeated Legacy Short Training field), HE-SIG-A (High Efficiency Signal A field), HE-SIG-B (High Efficiency Signal B field), HE-STF (High Efficiency Short Training field), and HE-LTF (High Efficiency Long Training field) in addition to the legacy preamble. In embodiments of the present invention, RL-SIG, HE-SIG-A, HE-SIG-B, HE-STF, and HE-LTF can be referred to as the HE preamble. The specific configuration of the HE preamble may be modified according to the HE PPDU format. For example, HE-SIG-B may be used only in the HE MU PPDU format.

[0063] Referring to Figure 7(c), the EHT PPDU preamble further includes RL-SIG (Repeated Legacy Short Training field), U-SIG (Universal Signal field), EHT-SIG-A (Extremely High Throughput Signal A field), EHT-SIG-A (Extremely High Throughput Signal B field), EHT-STF (Extremely High Throughput Short Training field), and EHT-LTF (Extremely High Throughput Long Training field) in addition to the legacy preamble. In embodiments of the present invention, RL-SIG, EHT-SIG-A, EHT-SIG-B, EHT-STF, and EHT-LTF can be referred to as the 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 in only some of the EHT PPDU formats.

[0064] The L-SIG field included in the PPDU preamble is configured with 64 FFT OFDM and consists of a total of 64 subcarriers. Of these, 48 subcarriers, excluding the guard subcarrier, DC subcarrier, and pilot subcarrier, are used for L-SIG data transmission. Since BPSK and a 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 Figure 7(d), L-SIG includes the L_RATE field and the L_LENGTH field. The L_RATE field consists 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 scheme such as BPSK / QPSK / 16-QAM / 64-QAM and a code rate such as 1 / 2, 2 / 3, or 3 / 4. Combining the information from the L_RATE and L_LENGTH fields allows us to determine the total length of the PPDU. In non-legacy PPDU formats, the L_RATE field is set to the minimum speed of 6 Mbps.

[0066] The L_LENGTH field is measured in bytes, with a total of 12 bits allocated, allowing for signaling up to 4095. In combination with the L_RATE field, it can indicate the length of the PPDU. In this case, legacy and non-legacy terminals can parse the L_LENGTH field in different ways.

[0067] First, the method by 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 6Mbps, 3 bytes (i.e., 24 bits) may be transmitted in 4us, which is the symbol duration of one 64FFT. Therefore, by adding the 3 bytes corresponding to the SVC field and the Tail field to the L_LENGTH field value and dividing this by the transmission amount of one symbol, which is 3 bytes, the number of 64FFT reference symbols after L-SIG is obtained. After multiplying the obtained number of symbols by 4us, which is the symbol duration of one symbol, and then adding 20us, which is the transmission time for L-STF, L-LTF, and L-SIG, the length of the PPDU, i.e., the reception time (RXTIME), is obtained. This can be expressed mathematically as shown in Equation 1 below.

[0068]

number

[0069] At this time,

number

[0070]

number

[0071] Here, TXTIME is the total transmission time that constitutes the PPDU, as shown in Equation 3 below. 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 ​​L_LENGTH = {3k+1, 3k+2, 3(k+1)} indicate the same PPDU length.

[0074] Referring to Figure 7(e), the U-SIG (Universal SIG) field persists in EHT PPDUs and subsequent generations of wireless LAN PPDUs, playing a role in distinguishing which generation of PPDU it is, including 11be. The U-SIG is a 64FFT-based OFDM with two symbols, capable of transmitting a total of 52 bits of information. Of these, 43 bits, excluding the 9 bits of CRC / tail, are broadly divided into the VI (Version Independent) field and the VD (Version Dependent) field.

[0075] The VI bit maintains its current bit configuration, allowing current 11be terminals to obtain information about a PPDU from its VI field even when subsequent generations of PPDUs are defined. To this end, the VI field consists of the PHY version, UL / DL, BSS color, TXOP, and Reserved fields. The PHY version field is 3 bits and is responsible for sequentially distinguishing 11be and subsequent generations of wireless LAN standards by version. 11be has a value of 000b. The UL / DL field distinguishes whether the PPDU is an uplink or downlink PPDU. The BSS color represents the BSS identifier defined in 11ax and has a value of 6 bits or more. The TXOP represents the Transmit Opportunity Duration, which was transmitted in the MAC header, but by adding it to the PHY header, the length of the TXOP containing the PPDU can be inferred without decoding the PPDU, and it has a value of 7 bits or more.

[0076] The VD field may consist of the PPDU format as signaling information useful only for the 11be version of PPDU, fields that are common to any PPDU format such as BW, and fields that are defined differently depending on the PPDU format. The PPDU format is a divisor that distinguishes between EHT SU (Single User), EHT MU (Multiple User), EHT TB (Trigger-based), EHT ER (Extended Range) PPDU, etc. The BW field broadly signals five basic PPDU BW options of 20, 40, 80, 160 (80+80), and 320 (160+160) MHz (BW that can be expressed in the form of a power of 20*2 can be called a basic BW), and various remaining PPDU BWs composed of preamble puncturing. In addition, after being signaled at 320 MHz, some 80 MHz may be punctured and then signaled. Furthermore, the punctured and deformed channel shape may be signaled directly in the BW field, or it may be signaled using both the BW field and fields appearing after the BW field (for example, fields within 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] Fields located after the BW field vary depending on the form and format of the PPDU. MU PPDUs and SU PPDUs may be signaled in the same PPDU format. A field to distinguish between MU PPDUs and SU PPDUs may be located before the EHT-SIG field, and additional signaling may be performed for this purpose. Both SU PPDUs and MU PPDUs include an EHT-SIG field, but some fields unnecessary for the SU PPDU may be compressed. In this case, the information of the compressed fields may be omitted or have a reduced size compared to the original fields included in the MU PPDU. For example, in the case of a SU PPDU, the common fields of the EHT-SIG may be omitted or replaced, or user-specific fields may be replaced or reduced to one, resulting in a different configuration.

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

[0079] If a portion of the EHT-SIG field of an SU PPDU is compressed, the information contained in the compressed field may be signaled together with the uncompressed field (e.g., a common field). In the case of MU PPDUs, 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 know the location of the RU to which the MU PPDU is transmitted, the STA to which each RU is assigned, and whether or not the transmitted MU PPDU was sent to them. Therefore, the AP must transmit the EHT-SIG field with the above information included. To this end, the U-SIG field signals information for efficient transmission of the EHT-SIG field, which may be the number of symbols in the EHT-SIG field and / or the modulation method, MCS. The EHT-SIG field may include size and location information of the RU assigned to each user.

[0080] In the case of an SU PPDU, multiple RUs may be assigned to the STA, and these RUs may be consecutive or discontinuous. If the RUs assigned to the STA are not consecutive, the STA can efficiently receive the SU PPDU only if it recognizes the punctured RU in the middle. Therefore, the AP can transmit the SU PPDU including information about the punctured RUs among the RUs assigned to the STA (e.g., the puncturing pattern of the RUs). That is, in the case of an SU PPDU, the EHT-SIG field may contain a puncturing mode field that includes information on whether a puncturing mode was applied and the puncturing pattern shown in bitmap format or similar, and the puncturing mode field can signal the form of discontinuous channels appearing within the bandwidth.

[0081] The form of the signaled discontinuous channels is limited and, in combination with the value of the BW field, indicates the BW and discontinuous channel information of the SU PPDU. For example, in the case of an SU PPDU, since it is a PPDU transmitted to only one terminal, the STA can recognize the bandwidth allocated to it from the BW field included in the PPDU, and can recognize the punctured resources within the allocated bandwidth from the puncturing mode field of the U-SIG field or EHT-SIG field included in the PPDU. In this case, the terminal can receive the PPDU with the remaining resource units excluding the specific channel of the punctured resource unit. At this time, the multiple RUs allocated to the STA may consist of different frequency bands or tones.

[0082] The reason only restricted forms of discontinuous channel configurations are signaled is to reduce the signaling overhead of the SU PPDU. Since puncturing can be performed on each 20MHz subchannel, when puncturing is performed on a bandwidth with multiple 20MHz subchannels, such as 80, 160, and 320MHz, in the case of 320MHz, the usage status of the remaining 15 20MHz subchannels (excluding the primary channel) must be represented, and the discontinuous channel configuration (if a configuration where only the end 20MHz is punctured is also considered discontinuous) must be signaled. Using 15 bits to signal the discontinuous channel configuration for single-user transmission in this way can result in excessive signaling overhead when considering the low transmission speed of the signaling portion.

[0083] This invention proposes a method for signaling the discontinuous channel configuration of an SU PPDU, and illustrates the discontinuous channel configuration determined by the proposed method. Furthermore, it proposes a method for signaling the primary 160MHz and secondary 160MHz puncturing configurations in a 320MHz BW configuration of an SU PPDU. The permissible discontinuous channel configurations when the above discontinuous channel configuration definition method is applied, and the method for signaling the discontinuous channel configuration using 3 bits, are shown in Figures 17 to 19.

[0084] Furthermore, 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 differs depending on the signaled PPDU format in the PPDU format field. Assuming that the BW field is 4 bits, in the case of an EHT SU PPDU or TB PPDU, one symbol of EHT-SIG-A is further signaled after U-SIG, or it is not necessary to signal EHT-SIG-A from the beginning. Taking this into consideration, it is necessary to fully signal up to 11 puncturing modes using only the BW field of U-SIG. However, in the case of an EHT MU PPDU, EHT-SIG-B is further signaled after U-SIG, so up to 11 puncturing modes can be signaled in a different way than in an SU PPDU. In the case of an EHT ER PPDU, the BW field can be set to 1 bit to signal whether the PPDU uses a 20MHz or 10MHz bandwidth. Detailed puncturing patterns for each PPDU type will be described in detail in Figures 11 and 12.

[0085] Figure 7(f) shows the format-specific fields of the VD field when EHT MU PPDU is indicated in the U-SIG PPDU format field. 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 fields.

[0086] Figure 8 shows examples of various EHT (Extremely High Throughput) PPDU (Physical Protocol Data Unit) formats and methods for specifying them according to embodiments of the present invention.

[0087] Referring to Figure 8, a PPDU may consist of a preamble and a data portion, and one type of format, EHT PPDU, may be distinguished by a U-SIG field included in the preamble. Specifically, whether or not the PPDU format is an EHT PPDU may be indicated based on the PPDU format field included in the U-SIG field.

[0088] Figure 8(a) shows an example of the 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 may have an EHT-SIG-A field for additional signaling after the U-SIG field.

[0089] Figure 8(b) shows an example of an EHT trigger-based PPDU format, which is an EHT PPDU transmitted based on a trigger frame. An EHT trigger-based PPDU is an EHT PPDU transmitted based on a trigger frame and is an uplink PPDU used as a response to a trigger frame. Unlike an EHT SU PPDU, an EHT PPDU does not have an EHT-SIG-A field after the U-SIG field.

[0090] Figure 8(c) shows an example of the EHT MU PPDU format, which is an EHT PPDU for multiple users. An EHT MU PPDU is a PPDU used to send a PPDU to one or more STAs. In the EHT MU PPDU format, the HE-SIG-B field may be located after the U-SIG field.

[0091] Figure 8(d) shows an example of the EHT ER SU PPDU format used for single-user transmissions with STAs in an extended range. EHT ER SU PPDU may be used for single-user transmissions with STAs in a wider range than EHT SU PPDU described in Figure 8(a), and the U-SIG field may be repeatedly positioned on the time axis.

[0092] The EHT MU PPDU described in Figure 8(c) can be used by an AP to transmit downlink data to multiple STAs. In this case, the EHT MU PPDU can include scheduling information so that multiple STAs can simultaneously receive PPDUs transmitted from the AP. The EHT MU PPDU can transmit the AID information of the recipient and / or sender of the PPDU transmitted through the user-specific field of EHT-SIG-B to the STAs. Therefore, multiple terminals that receive the EHT MU PPDU can perform spatial reuse operations based on the AID information in the user-specific field included in the preamble of the received PPDU.

[0093] Specifically, the resource unit allocation (RA) field in the HE-SIG-B field included in the HE MU PPDU may contain information about the configuration of resource units (e.g., resource unit division configuration) within a specific bandwidth on the frequency axis (e.g., 20 MHz). That is, the RA field can instruct the STA on the configuration of resource units divided by the bandwidth for transmitting the HE MU PPDU in order to receive the PPDU. Information about the STA allocated (or specified) to each divided resource unit may be included in the user-specific field of EHT-SIG-B and transmitted to the STA. That is, the user-specific field may contain one or more user fields corresponding to each divided resource unit.

[0094] For example, among the multiple divided resource units, the user field corresponding to at least one resource unit used for data transmission may contain the recipient's or sender's AID, while the user fields corresponding to the remaining resource units not used for data transmission may contain a previously set Null STA ID.

[0095] For the sake of clarity, the terms frame or MAC frame may be used interchangeably with MPDU in this specification.

[0096] When a single wireless communication device communicates using multiple links, the communication efficiency of the wireless communication device can be increased. In this case, a link is a physical path and may be configured as a single wireless medium that can be used to transmit an MSDU (MAC service data unit). For example, if the frequency band of 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 make effective use of multiple channels. Furthermore, when the wireless communication device communicates simultaneously using multiple links, the overall throughput can be increased. However, existing wireless LANs are defined on the premise that one wireless communication device uses one link. Therefore, a wireless LAN operation method for using multiple links is necessary. Referring to Figures 9 to 26, the wireless communication method for a wireless communication device using multiple links will be explained. First, using Figure 9, a specific form of a wireless communication device using multiple links will be explained.

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

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

[0099] Multiple stations included in a multilink system can operate on multiple links. Furthermore, multiple stations included in a multilink system can operate on multiple channels. Specifically, multiple stations included in a multilink system can operate on different links or different channels. For example, multiple stations included in a multilink system can operate on different channels of 2.4GHz, 5GHz, and 6GHz.

[0100] The operation of a multilink device can be called multilink operation, MLD operation, or multi-band operation. Furthermore, if the station paired with the multilink device is an AP (Application Platform), the multilink device can be called an AP MLD (Application Platform Multilink). Conversely, if the station paired with the multilink device is a non-AP station, the multilink device can be called a non-AP MLD (Application Platform Multilink).

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

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

[0103] Multilink configuration may be established through negotiations between peer stations. Specifically, multilink configuration may be performed through communication between stations without communication with the AP. Furthermore, multilink configuration may be established through any one of the links. For example, even if links 1 through 3 are configured via a multilink, the multilink configuration may be performed through link 1.

[0104] Furthermore, a mapping between TIDs (traffic identifiers) and links may be configured. Specifically, frames corresponding to a specific TID value may be exchanged only through pre-specified links. The mapping between TIDs and links may be configured in a directional-based manner. For example, if multiple links are configured between a first multilink device and a second multilink device, the first multilink device may be configured to send frames with a first TID to multiple first links, and the second multilink device may be configured to send frames with a second TID to the first links. Additionally, a default setting may exist for the mapping between TIDs and links. Specifically, if there are no additional settings in the multilink configuration, the multilink device can exchange frames corresponding to TIDs on each link according to the default setting. In this case, the default setting may be such that all TIDs are exchanged on any one link.

[0105] Let's explain TID in detail. TID is an ID used to classify traffic and data to support QoS (Quality of Service). TID may be used and assigned at layers higher than the MAC layer. TID can also indicate traffic category (TC) and traffic stream (TS). There may be 16 distinct TID values. For example, a TID may be specified as one of the values ​​from 0 to 15. Different TID values ​​may be specified depending on the access policy, channel access, or 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, TID can indicate user priority (UP). In this case, UP may be specified by TC or TS. UP may be assigned at layers higher than MAC. Furthermore, when HCCA (HCF controlled channel access) or SPCA is used, the TID value may be assigned in the range of 8 to 15. When HCCA or SPCA is used, TID can represent TSID. Furthermore, when HEMM or SEMM is used, the TID value may be assigned in the range of 8 to 15. When HEMM or SEMM is used, TID can represent TSID.

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

[0107] As mentioned above, a TID may be mapped to each of multiple links. The mapping may specify which links can exchange traffic corresponding to a particular TID or AC. Additionally, TIDs or ACs that can be transmitted in different transmission directions within a link may be specified. As mentioned above, a default setting may exist for the mapping between TIDs and links. Specifically, in a multilink configuration where no additional settings are made, the multilink device can exchange frames corresponding to TIDs 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 always 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 that link may be transmitted on that link. Therefore, when a link is mapped to a TID or AC, frames that do not correspond to a TID or AC not mapped to that link do not need to be transmitted on that link. When a link is mapped to a TID or AC, the 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 TIDs and links. Furthermore, in other specific embodiments, the mapping between TIDs and links may be determined based on a block ACK agreement. Specifically, a block ACK agreement may be set for a TID mapped to a particular link.

[0109] The aforementioned mapping of TIDs to links may ensure QoS. Specifically, a relatively small number of stations may be operational, or higher-priority ACs or TIDs may be mapped to links with good channel conditions. Furthermore, the aforementioned mapping of TIDs to links may enable stations to maintain a power-saving state for longer periods.

[0110] Figure 10 shows an example of the present invention in which transmissions on different links are performed simultaneously in multilink operation.

[0111] The implementation of multilink devices may not support simultaneous transmission on multiple links, simultaneous reception on multiple links, or transmission on one link while simultaneously receiving on other links. This is because reception or transmission on one link may affect reception or transmission on other links. Specifically, transmission on one link may act as interference on other links. Interference from one link of a multilink device to other links can be called internal leakage. Internal leakage may increase as the frequency spacing between links decreases. If internal leakage is not too large, transmission on one link may occur on other links simultaneously. If internal leakage is large, transmission on one link may not occur on other links simultaneously. Thus, simultaneous transmission on multiple links by a multilink device, transmission on one link while simultaneously receiving on other links, or simultaneous reception on multiple links can be called STR (simultaneous transmit and receive). As mentioned above, multilink devices do not need to support STR. In other specific embodiments, the multilink device may restrictively support STR. Specifically, the multilink device may support STR only under certain conditions. For example, STR of the multilink device may not be performed when the multilink device is operating as a single radio. Also, STR of the multilink device may not be performed when the multilink device is operating as a single antenna. Furthermore, STR of the multilink device may not be performed when internal leakage is detected to be above a predetermined level.

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

[0113] In Figure 10, the first station (STA1) and the second station (STA2) are linked to a single non-AP multilink device. Alternatively, the first AP (AP1) and the second AP (AP2) may also be linked to a single 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 can perform STR (Signal Transmission) to a limited extent. When the second station (STA2) transmits on the second link (Link2), reception by the first station (STA1) on the first link (Link1) may be interfered with. For example, the second station (STA2) transmits first data (Data1) on the second link (Link2), and the first AP (AP1) sends a response (Ack for Data1) to the first station (STA1). On the second link (Link2), the second station (STA2) transmits the second data (Data2). At this time, the timing of the transmission of the second data (Data2) and the timing of the transmission of the response for the first data (Data1) (Ack for Data1) may overlap. In this case, the transmission to the second station (STA2) on the second link (Link2) may cause interference on the first link (Link1). As a result, the first station (STA1) may not receive the response for the first data (Data1) (Ack for Data1). Figure 10(a) shows the 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, a multilink device can independently perform channel access, such as backoff, on multiple links. In this case, the backoff counter may reach zero on multiple links, and transmission may begin simultaneously on multiple links. Furthermore, in another specific embodiment, if the backoff counter of any one link of the multilink device reaches zero, the multilink device may perform channel access after only energy detection (ED) on that link and the other links. If no energy above a certain magnitude is detected, the multilink device may perform channel access on the link where energy detection was performed. This allows the multilink device to start transmitting simultaneously on multiple links. The threshold value used for energy detection may be smaller than the threshold value used when deciding whether or not to reduce the backoff counter. Also, when deciding whether or not to reduce the backoff counter, the station can detect any form of signal, not just wireless LAN signals. Furthermore, with the aforementioned energy detection, the station can detect any form of signal, not just wireless LAN signals. Internal leakage may not be detected as a wireless LAN signal. In such cases, the station may sense the signal detected by internal leakage as an energy detection. Furthermore, as mentioned above, the threshold used for energy sensing can be smaller than the threshold used to determine whether or not to reduce the backoff counter. Therefore, even when transmissions are taking place on other links, the multilink device can reduce the backoff counter on any one link, as shown in Figures 10(a) and 10(b).

[0115] The operation method of the multilink device when there is a limitation on STR will be explained with reference to Figures 11 to 25. However, the embodiment of the present invention may also be applied to the multilink device when there is no limitation on STR.

[0116] Figures 11 to 15 illustrate the case where multiple PPDUs are transmitted or can be transmitted simultaneously on multiple links. Furthermore, the embodiments described using Figures 11 to 15 may be applied when STR is not possible on multiple links where multiple PPDUs are transmitted. The embodiments described using Figures 11 to 15 may be applied when a multilink device receiving multiple PPDUs cannot receive on other links when transmitting on one link. The embodiments described using Figures 11 to 15 may be applied when a multilink device transmitting multiple PPDUs cannot receive on other links when transmitting on one link.

[0117] Figure 11 shows the operation in which a multilink device according to an embodiment of the present invention simultaneously terminates transmission on multiple links.

[0118] When a multilink device transmits on multiple links, it can terminate transmission on multiple links simultaneously. Specifically, the termination points of PPDUs transmitted on multiple links may be the same. Furthermore, such embodiments may apply not only when the multilink device starts transmitting on multiple links simultaneously, but also when it does not start transmitting on multiple links simultaneously. Such operation may be for multilink devices that cannot transmit and receive simultaneously. For example, it may be for a multilink device that receives multiple PPDUs but cannot transmit and receive simultaneously. Or, it may be for a multilink device that transmits multiple PPDUs but cannot transmit and receive simultaneously. Specifically, as shown in Figure 10(a), it may be for preventing the inability to receive an ACK on another link while transmission is taking place on one link. Therefore, when a multilink device does not support reception on other links while transmitting on one link, it may terminate transmission on multiple links simultaneously.

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

[0120] In the embodiment shown in Figure 11, the multilink device cannot receive on one link while transmitting on another. 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 complete the transmission of the first data (Data1) and the second data (Data2), respectively. Therefore, the acknowledgment for the first data (Ack for Data1) and the acknowledgment for the second data (Ack for Data2) are transmitted simultaneously without any internal leakage, and the multilink device can simultaneously receive the acknowledgment for the first data (Ack for Data1) and the acknowledgment for the second data (Ack for Data2).

[0121] Figure 12 shows the operation in which a multilink device according to an embodiment of the present invention terminates transmission on one of the links first when transmitting on multiple links.

[0122] When a multilink device is transmitting on one link and then starts transmitting on another link, or starts transmitting on multiple links simultaneously, the multilink device is not required to terminate the transmission on the other links later than the transmission on the other link. Therefore, the multilink device can terminate the transmission on other links before or simultaneously with the transmission on the other link. Specifically, when a multilink device is transmitting on one link and then starts transmitting on another link, and no response frame is expected for the frame transmitted on the other link, the multilink device can terminate the transmission on the other link before or simultaneously with the transmission on the other link. In this case, the response frame may be an immediate response frame. An immediate response frame can indicate that the interval between the frame and the response frame is within a predetermined time interval. In this case, the predetermined time interval may be SIFS. Furthermore, when no response frame is expected, this can include cases where an ACK is not requested, as explained using Figure 11. Specifically, a frame requesting an immediate response frame may include a frame requesting an ACK. Furthermore, a frame requesting an immediate response may include a frame that triggers an uplink transmission. A frame requesting an immediate response may also include a QoS data frame requesting an immediate response. A frame requesting an immediate response may also include a control frame requesting an immediate response. Furthermore, a frame requesting an immediate response may also include a management frame requesting an immediate response. Additionally, for a PPDU to include a frame requesting an immediate response, it is sufficient that at least one of the frames included in the PPDU requests an immediate response. For a PPDU to include a frame requesting an immediate response to a station, it is sufficient that at least one of the frames included in the PPDU requests an immediate response to the station.When a multilink device transmits on any one link in a way that does not expect a response frame, it is permissible for the multilink device not to terminate transmission on other links before it has terminated transmission on the other link. Therefore, when a multilink device transmits on any one link in a way that does not expect a response frame, it can terminate transmission on other links after it has terminated transmission on the other link. When a multilink device transmits on any one link in a way that does not expect a response frame, and the frames transmitted on other links request a response frame, it is permissible for the multilink device not to terminate transmission on other links before it has terminated transmission on the other link. In this case, the response frame may be an immediate response frame. Therefore, when a multilink device transmits only multiple PPDUs that do not contain frames requesting a response, or when it transmits one PPDU containing a frame requesting a response and another PPDU requesting a response simultaneously, the multilink device does not need to terminate the transmission of multiple PPDUs simultaneously. In this case, the multilink device can transmit multiple PPDUs such that the end of transmission of a PPDU containing only frames that do not require a response does not occur later than the end of transmission of a PPDU containing frames that require a response.

[0123] In the embodiment shown in Figure 12, the multilink device cannot receive on one link while transmitting on another. The first station (STA1) and the second station (STA2) of the multilink device transmit the first data (Data1) and the 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 request an ACK. The second station (STA2) finishes transmitting the second data (Data2) before the first station (STA1) finishes. Therefore, the transmission by the second station (STA2) does not interfere with the first station (STA1) receiving an ACK (Ack for Data1) for the first data.

[0124] Furthermore, the above-described embodiment may be applied when a multilink device is unable to receive on another link while transmitting on one link.

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

[0126] A multilink device may not be able to transmit on multiple links simultaneously. Specifically, a multilink device can transmit on only one of several links. For example, if a multilink device is transmitting on one link and cannot receive on the other links, it can transmit on only one of several links. In these embodiments, the multilink device can postpone transmission during channel access. Channel access as described herein may refer to channel access including the backoff procedure described earlier with reference to Figure 6. Specifically, a multilink device can postpone transmission on all links except the one on which it is transmitting. For example, a multilink device can perform a backoff procedure on multiple links. In this case, the multilink device can transmit on the link whose backoff counter reaches zero first and reset the backoff counters on the remaining links. Also, if the backoff counters on multiple links reach zero, the multilink device can transmit on one of the multiple links. In this case, the multilink device can randomly select one of the multiple links and transmit on the selected link. The multilink device can also reset the backoff counters on the unselected links. A reset can represent the multilink device setting a randomly selected value within CW to the backoff counter. The multilink device can also reset the CW on links that have not been transmitted. Specifically, the multilink device can set the CW on links that have not been transmitted to the minimum CW value, CWmin. These embodiments may be applied when the multilink device is transmitting on one link and unable to receive on the other links.

[0127] In further specific embodiments, a multilink device can determine how to access channels on multiple links depending on whether or not it is unable to transmit on one link and receive on the other links. Specifically, if a multilink device cannot transmit on one link and receive on the other links, it does not need to access channels independently on multiple links. If a multilink device can transmit on one link and receive on the other links, it may access channels independently on multiple links.

[0128] As shown in Figures 11 and 12 above, the multilink device can adjust the length of the PPDU to comply with the constraints imposed by the simultaneous conditions. In this case, if it is difficult for the multilink device to adjust the length of the PPDU until the time of transmission, the multilink device can transmit on only one of the multiple links. Also, if the transmission time allowed on any 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 in 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 shown in Figure 13, the multilink device performs channel access, including backoff, independently on the first link (Link1) and the second link (Link2). The backoff counters for both the first link (Link1) and the second link (Link2) reach 0 simultaneously. 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 embodiment described above, when the multilink device postponed transmission, the multilink device reset the backoff counter. In yet another specific embodiment, when the multilink device postpones transmission, the multilink device may maintain the value of the backoff counter. This ensures that the transmission balance between links, which may be reduced by the transmission postponement, is maintained.

[0131] Figure 14 shows the operation in which a multilink device according to an embodiment of the present invention terminates transmission on one of the links first when transmitting on multiple links.

[0132] As illustrated in the embodiment shown in Figure 11, when a multilink device transmits on multiple links, the multilink device can terminate transmission on multiple links simultaneously. Specifically, the multilink device can terminate PPDU transmission on multiple links simultaneously. This simultaneous termination of multiple PPDU transmissions can be referred to as aligning the ends of the PPDUs. Furthermore, multiple PPDUs can be said to be aligned if the difference between the transmission termination times of multiple PPDUs is less than or equal to a threshold. In this case, the threshold may be a pre-specified value. Specifically, the threshold may be a value set based on SIFS. Alternatively, the threshold may be a value set based on the length of SIFS and signal extension. For example, the threshold may be the value obtained by dividing the sum of the length of SIFS and signal extension by 2. In this case, the threshold may be 8us.

[0133] When a multilink device transmits multiple PPDUs to another multilink device via multiple links, the multilink device can align the ends of the multiple PPDUs. When a multilink device transmits multiple PPDUs to another multilink device via multiple links, the multilink device can align the ends of two or more PPDUs. In this case, one multilink device can be the transmitting multilink device, and the other multilink device can be the receiving multilink device. The transmitting or receiving multilink device may be a multilink device that does not support STR or supports STR to a limited extent. A multilink device that does not support STR or supports STR to a limited extent can be called a non-STR multilink device. A multilink device that supports STR can be called an STR multilink device.

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

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

[0136] In these embodiments, the transmission direction from the AP or AP multilink device to the non-AP STA or non-AP multilink device can be called the downlink (DL). The transmission direction from the non-AP STA or non-AP multilink device to the AP or AP multilink device can be called the uplink (UL). The frames and PPDUs transmitted by 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 by 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 aforementioned embodiment of aligning the ends of multiple PPDUs may be applied only if at least one of the multiple PPDUs contains a frame requesting an immediate response.

[0138] In the embodiment described above, multiple PPDUs may be transmitted to a single multilink device via multiple links. Specifically, a receiving multilink device can receive multiple PPDUs from multiple stations belonging to a single multilink device via multiple links. For example, a receiving multilink device operates on a first link and a second link. The first station of the receiving multilink device operates on the first link, and the second station of the receiving multilink device operates on the second link. While the first PPDU is transmitted to the first station on the first link, the second PPDU is transmitted to the second station on the second link, and the ends of the first and second PPDUs may be aligned if each of them contains a frame requesting an immediate response.

[0139] In the embodiments described above, the transmission of multiple PPDUs over multiple links can represent the simultaneous transmission of multiple PPDUs. Furthermore, the transmission of multiple PPDUs over multiple links can represent simultaneous transmission at any given time. The simultaneous transmission of multiple PPDUs may mean that even if the start times of transmission for the multiple PPDUs are not the same, there is a point in time when they are transmitted simultaneously. The simultaneous transmission of multiple PPDUs may mean that even if the end times of transmission for the multiple PPDUs are not the same, there is a point in time when they are transmitted simultaneously.

[0140] In another specific embodiment, if at least one of the multiple PPDUs transmitted over multiple links contains a high-priority frame, the multilink device does not need to align the ends of the multiple PPDUs. In this case, the high-priority frame may be a frame with a higher priority than a pre-specified priority. Alternatively, the high-priority frame may be a pre-specified frame. This allows the multilink device to improve the transmission efficiency of high-priority frames.

[0141] In the embodiments described above, if only some of the multiple PPDUs satisfy a predetermined condition, the multilink device can align only the ends of the some PPDUs that satisfy the predetermined condition. When the multilink device transmits multiple PPDUs, the multilink device can align the ends of the multiple PPDUs that contain frames requesting immediate responses. For example, if only two of the multiple PPDUs contain frames requesting immediate responses, the multilink device can align only the ends of the two PPDUs that contain frames requesting immediate responses. In these embodiments, the multilink device does not need to align the ends of PPDUs that do not contain frames requesting immediate responses with the ends of the multiple PPDUs that contain frames requesting immediate responses. Specifically, the multilink device can transmit PPDUs that do not contain frames requesting immediate responses so that their ends are not slower than the ends of PPDUs that contain frames requesting immediate responses.

[0142] In the embodiment shown in Figure 14, the AP multilink device includes a first AP (AP1), a second AP (AP2), and a third AP (AP3). The non-AP multilink device includes a first station (STA1), a second station (STA2), and a third station (STA3). The AP multilink device or the non-AP multilink device may be a non-STR multilink device. Specifically, the non-AP multilink device may be a non-STR multilink device. Each of the first AP (AP1), second AP (AP2), and 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), second station (STA2), and third station (STA3) using the first link (Link1), second link (Link2), and 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) that does not request an immediate response. The AP multilink device does not need to align 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 ends of the first PPDU (PPDU1) and the second PPDU (PPDU2). In this case, the end of the third PPDU (PPDU3) may be the same as or earlier than the end of the first PPDU (PPDU1) and the second PPDU (PPDU2).

[0143] Figure 15 shows the operation in which a multilink device according to yet another embodiment of the present invention terminates transmission on one of the links first when transmitting on multiple links.

[0144] When a sender multilink device transmits multiple PPDUs to a receiver multilink device over multiple links, the sender multilink device can determine the transmission length of each of the multiple PPDUs based on whether or not each of the multiple PPDUs contains a frame requesting an immediate response. Specifically, the sender multilink device can determine that the transmission of PPDUs that do not contain a frame requesting an immediate response ends at the same time as or earlier than the transmission of PPDUs that contain a frame requesting an immediate response. Therefore, the sender multilink device can determine that the transmission of PPDUs containing a frame requesting an immediate response ends at the same time as or later than the transmission of PPDUs that do not contain a frame requesting an immediate response. In such embodiments, the sender multilink device or receiver multilink device may be a non-STR multilink device.

[0145] In the embodiment shown in Figure 15, the AP multilink device includes a first AP (AP1) and a second AP (AP2). The non-AP multilink device includes a first station (STA1) and a second station (STA2). The AP multilink device or the non-AP multilink device may be a non-STR multilink device. Specifically, the non-AP multilink device may be a non-STR multilink device. The first AP (AP1) and the second AP (AP2) can each transmit a first PPDU (PPDU1) and a second PPDU (PPDU2) to the first station (STA1) and the second station (STA2) respectively using the first link (Link1) and the second link (Link2), respectively. The first PPDU (PPDU1) includes first data (Data1) requesting an immediate response, and the second PPDU (PPDU2) includes only second data (Data2) that does not request an immediate response. In this case, the second data (Data2) may be an A-MPDU containing only MPDUs that do not require an immediate response. 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). The first PPDU (PPDU1) and the second PPDU (PPDU2) may be either SU PPDUs or MU PPDUs. The AP multilink device can 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 using Figure 15 may be applied regardless of the start time of PPDU transmission. Specifically, as shown in Figure 15(a), the transmission start of the first PPDU (PPDU1) may be earlier than the transmission start of the second PPDU (PPDU2). Furthermore, as shown in Figure 15(b), the start of transmission of the first PPDU (PPDU1) may be later than the start of transmission of the second PPDU (PPDU2).

[0146] Based on Figures 10 to 15, the examples demonstrate that problems that may arise due to internal leakage can be solved.

[0147] The mapping between the link and TID may be set up as in the embodiment described using Figure 9. The specific operation method of the multilink device will be explained using Figures 16 to 20.

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

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

[0150] Specifically, if a restriction is applied to the end of transmission on any one link, frames corresponding to TIDs not mapped to that link may be transmitted on that link. In a specific embodiment, when a multilink device transmits, the multilink device can set the end of transmission on the second link based on the end of transmission on the first link. In this case, the multilink device can transmit both MPDUs corresponding to TIDs mapped to the second link and MPDUs corresponding to TIDs not mapped to the second link. The multilink device can also compare the value of the TID not mapped to the link with the value of the TID mapped to the link, and based on the comparison result, can decide whether or not to transmit both MPDUs corresponding to the TID mapped to the second link and MPDUs corresponding to TIDs not mapped to the second link. For example, if the value of the TID not mapped to the link is greater than the value of the TID mapped to the link, the multilink device can transmit both MPDUs corresponding to the TID mapped to the link and MPDUs corresponding to TIDs not mapped to the second link. In yet another specific embodiment, if 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 the MPDU corresponding to the TID mapped to the link and the MPDU corresponding to the TID not mapped to the second link.

[0151] In further specific embodiments, the multilink device can compare the priority levels corresponding to TIDs not mapped to a link with the priority levels corresponding to TIDs mapped to a link, and based on the comparison result, can decide whether to transmit both MPDUs corresponding to TIDs mapped to a link and MPDUs corresponding to TIDs not mapped to a link on that link. In this case, the priority levels may be TC (traffic class) or AC (access category).

[0152] The AP multilink device includes a first AP (AP1) and a second AP (AP2). The non-AP multilink device also includes a first station (STA1) and a second station (STA2). The first link (Link1) is mapped to the first TID (TID0) and the third TID (TID2), and the second link (Link2) is mapped to the second TID (TID1). The non-AP multilink device transmits an MPDU on the second link (Link2) corresponding to the third TID (TID2), which is not mapped to the second link (Link2). Specifically, the non-AP multilink device transmits a PPDU on the second link (Link2) that includes an MPDU mapped to the first TID (TID0), which is mapped to the second link (Link2), and an MPDU corresponding to the third TID (TID2), which is not mapped to the second link (Link2). In this case, the non-AP multilink device sends an MPDU on the second link (Link2) that corresponds to a third TID (TID2) that is not mapped to the second link (Link2), provided that the pre-specified conditions are met. 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 send an MPDU on the second link (Link2) that corresponds to a third TID (TID2) that is not mapped to the second link (Link2). Also, when the non-AP multilink device aligns the end of transmission on the first link with the end of transmission on the second link, there is insufficient traffic to be transmitted on the second link (Link2), allowing the non-AP multilink device to send an MPDU on the second link (Link2) that corresponds to a third TID (TID2) that is not mapped to the second link (Link2).

[0153] When a multilink device selects a link to use for transmission from among several links, the multilink device can transmit frames corresponding to TIDs that are not mapped to the selected link on the selected link. Specifically, when a multilink device selects a link to use for transmission from among several links, the multilink device can transmit frames corresponding to TIDs mapped to links that were not selected among the multiple links on the selected link. Specifically, such an embodiment may be applied to the embodiment described with reference to Figure 13.

[0154] In these embodiments, a question may arise as to which link the multilink device should send a response to a frame corresponding to a TID that is not mapped to a link. The multilink device can send a response to a frame on the link from which the frame corresponding to the unmapped TID was transmitted. In this case, the response to the frame may be an ACK. For example, in the embodiment shown in Figure 16, the AP multilink device can send an ACK on the first link (Link1) for the frame corresponding to the first TID (TID0) and an ACK on the first link (Link1) for the frame corresponding to the third TID (TID2) transmitted on the first link (Link1). The AP multilink device can also send an ACK on the second link (Link2) for the frame corresponding to the second TID (TID1) and an ACK on the second link (Link2) for the frame corresponding to the third TID (TID2) transmitted on the second link (Link2). In these embodiments, since the multilink device sends a response to a frame on the link from which the frame was received, the complexity of implementation can be reduced.

[0155] In further specific embodiments, the multilink device can transmit a response to a frame corresponding to a TID that is not mapped to a link, but rather on the link from which the frame was transmitted. In this case, the response to the frame may be an ACK. For example, in the embodiment shown in Figure 16, the AP multilink device can transmit an ACK for a frame corresponding to the first TID (TID0) and an ACK for a frame corresponding to the third TID (TID2) on the first link (Link1). The AP multilink device can also transmit an ACK for a frame corresponding to the second TID (TID1) on the second link (Link2). In these embodiments, since the response to a frame corresponding to a TID is transmitted through a link that is not mapped to a TID, the processing burden of having to aggregate responses transmitted on multiple links can be reduced.

[0156] Figure 16 illustrates the exception situations that may be transmitted regardless of the mapping between links and TIDs. Figures 17 and 18 further illustrate the exception situations that may be transmitted regardless of the mapping between links and TIDs using other specific examples.

[0157] Figure 17 shows the operation of a station according to an embodiment of the present invention performing UL MU transmission. Figure 18 shows a multilink device according to an embodiment of the present invention aggregating multi-TIDs.

[0158] As mentioned above, when a time limit is applied to the transmission end date, the multilink device can compare the priority of a TID that is not mapped to a link with the priority of a TID that is mapped to a link. In this case, the multilink device can decide whether or not to transmit the MPDU corresponding to the TID that is not mapped to a link on that link, based on the comparison result. Specifically, if the priority of an MPDU corresponding to an MPDU that is not mapped to a link is higher than the priority of an MPDU corresponding to an MPDU that is mapped to a link, the multilink device can transmit the MPDU corresponding to the TID that is not mapped to a link on that link. For example, if the MPDU corresponding to an MPDU that is not mapped to a link has the highest priority, the multilink device can transmit the MPDU corresponding to the TID that is not mapped to a link on that link.

[0159] In further specific embodiments, if the priority of an MPDU corresponding to a TID not mapped to a link is lower than the priority of an MPDU corresponding to a TID mapped to a link, the multilink device can transmit an MPDU corresponding to a TID not mapped to a link over that link. For example, if an MPDU corresponding to a TID not mapped to a link has the lowest priority, the multilink device can transmit an MPDU corresponding to a TID not mapped to a link over that link. This gives the multilink device an opportunity to transmit traffic that would otherwise be difficult to transmit due to its low priority.

[0160] A multilink device may only transmit an MPDU corresponding to a TID not mapped to a link on that link if both an MPDU corresponding to a TID mapped to a link and an MPDU corresponding to a TID not mapped to a link are transmitted. Specifically, the transmission of both an MPDU corresponding to a TID mapped to a link and an MPDU corresponding to a TID not mapped to a link may be carried out as follows: An A-MPDU (aggregate-MPDU) transmitted on any one link may be an aggregate of an MPDU corresponding to a TID mapped to that link and an MPDU corresponding to a TID not mapped to that link. In addition, a PPDU transmitted on any one link may include an MPDU corresponding to a TID mapped to that link and an MPDU corresponding to a TID not mapped to that link.

[0161] These embodiments may be applied to UL MU transmission operations. First, the UL MU transmission operation will be explained using Figure 17.

[0162] Multiple stations may transmit PPDUs simultaneously. This type of transmission, or the series of processes leading up to such transmissions, is called an uplink (UL) multi-user (MU) operation or UL MU transmission. For an UL MU transmission to occur, an operation to trigger transmissions from multiple stations may precede it.

[0163] Furthermore, when multiple stations transmit a single PPDU simultaneously, the multiple stations can use a TB (trigger-based) PPDU. A TB PPDU can include the HE TB PPDU and EHT TB PPDU mentioned above. A TB PPDU can also represent a PPDU that supports simultaneous transmission by multiple stations. Multiple stations can receive a frame that triggers UL MU transmission, and the multiple stations can perform UL MU transmission based on the received frame. An AP can send a frame that triggers UL MU transmission to multiple stations. The frame that triggers UL MU transmission can also indicate the resource unit (RU) assigned to each of the multiple stations in the UL MU transmission in which the UL MU transmission takes place. Stations can transmit a TB PPDU with the RU assigned to them. The frame that triggers UL MU transmission may be a trigger frame or a frame containing trigger information. A frame containing trigger information can include the trigger information in the MAC header. Specifically, a frame containing trigger information can include the trigger information in the A-Control field. Specifically, the trigger information may be in the TRS (triggered response scheduling) control field. Furthermore, UL MU transmissions may be transmitted using the aforementioned TB PPDU. Multiple stations can also perform UL MU transmissions in immediate response. That is, the interval between the PPDU containing the frame triggering the UL MU transmission and the PPDU containing the UL MU transmission may be SIFS.

[0164] A frame that triggers an UL MU transmission may contain information about the length of the PPDU containing the UL MU transmission. For convenience of explanation, this information about the length of the PPDU containing the UL MU transmission is referred to as response length information. Response length information can indicate the length of the PPDU containing the UL MU transmission. A station can determine the length of the PPDU containing the UL MU transmission based on the response length information contained in the frame that triggers the UL MU transmission. Specifically, response length information can indicate the value of the Length field in the L-SIG field of the PPDU containing the UL MU transmission. For example, a station can determine the value of the Length field in the L-SIG field of a TB PPDU based on the length field of the trigger frame. Furthermore, even if a station does not have enough traffic to generate a PPDU with response length information, the station can still determine the length of a TB PPDU using the response length information. Specifically, a station can insert padding into a TB PPDU. For example, if there are empty bits in a TB PPDU after the station has inserted all the traffic in its buffer into the TB PPDU, the station can insert padding into the empty bits. This allows the station to satisfy the length of the TB PPDU indicated by the response length information. The response length information can also indicate the number of OFDM symbols contained in the TB PPDU. Therefore, when a station performs an UL MU transmission, it transmits in accordance with the length indicated by the frame that triggers the UL MU transmission. Furthermore, any station performing an UL MU transmission can transmit a TB PPDU of the same length. In addition, the response to an UL MU transmission may be an immediate response to the UL MU transmission. Therefore, the interval between an UL MU transmission and its response may be SIFS.

[0165] Referring to Figure 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 with a RU indicating that the trigger frame is assigned to the first station (STA1) and the second station (STA2), respectively. 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 the response length information indicated in the trigger frame. The lengths of the TB PPDU transmitted by the first station (STA1) and the second station (STA2) are the same. Also, 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 frames included in the TB PPDU transmitted by each of the first station (STA1) and the second station (STA2). Thus, constraints regarding the end of transmission may also apply when a station transmits a TB PPDU. In this case, an example of a mapping exception between a link and a TID may be applied. This will be explained in detail using Figure 18.

[0166] When a station performs a UL MU transmission, it can transmit frames corresponding to TIDs that are not mapped to the link on which the UL MU transmission is being performed. Specifically, when a station performs a UL MU transmission, it can transmit both frames mapped to the link on which the UL MU transmission is being performed and frames corresponding to TIDs that are not mapped to that link. In Figure 18, the station transmits a TB PPDU through the first link (Link1). At this time, the uplink of the first link (Link1) is mapped to AC_VI and AC_BE. At this time, as shown in Figure 18(b), the station can transmit data frames or PDSUs corresponding to AC_VI and AC_BE, along with a TB PPDU including padding. However, in such an embodiment, if the padding length becomes excessively long, the transmission efficiency may decrease. Also, for a station that transmits a trigger frame, such as an AP, it is not possible to know exactly the traffic stored in the buffers of each of the multiple stations performing UL MU transmissions, and there is a high possibility that the padding length included in the TB PPDU will be large. Therefore, as shown in Figure 18(c), the station can further include data frames or PSDUs corresponding to other ACs not mapped to the first link (Link1), i.e., AC_VO, in the TB PPDU.

[0167] As mentioned above, the priority of TIDs mapped to a station link can be compared with the priority of TIDs not mapped to a link, and based on the comparison result, it can be determined whether or not to transmit frames corresponding to TIDs not mapped to a link on that link. For example, in Figure 18(c), AC_VO may have a higher priority than AC_VI or AC_BE, which are ACs mapped to the first link (Link1). Also, as mentioned above, a station cannot transmit a PPDU containing only frames corresponding to TIDs not mapped to a link, but can transmit both frames corresponding to TIDs mapped to a link and frames corresponding to TIDs not mapped to a link. In Figure 18, an embodiment of the present invention was illustrated using AC, but as mentioned above, these embodiments may also be applied when links are mapped to TIDs or TSIDs instead of AC.

[0168] Furthermore, the above-described embodiment may be applied in conjunction with a multi-TID aggregation rule. The multi-TID aggregation rule defines a rule by which MPDUs corresponding to different TIDs are aggregated into a single A-MPDU. Therefore, MPDUs aggregated by the multi-TID aggregation rule do not need to follow the mapping between links and TIDs. Specifically, when a station aggregates MPDUs by the multi-TID aggregation rule, it can transmit MPDUs corresponding to TIDs that are not mapped to a link on that link. The multi-TID aggregation rule may be as follows:

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

[0170] 2) At least one of the AC frames or MPDUs used when acquiring the main AC and TXOP is included in the assembled A-MPDU.

[0171] 3) A frame or TID that corresponds to an MPDU that is aggregated into A-MPDU is either the primary AC or a TID with a higher priority than the primary AC.

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

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

[0174] Furthermore, in other specific embodiments, condition 3) of the multi-TID set rule described above may be replaced by the following condition 3-1).

[0175] 3) A frame or TID that corresponds to an MPDU that is aggregated into A-MPDU is either the primary AC or a TID with a lower priority than the primary AC.

[0176] In further specific embodiments, a station may transmit a TID that is not mapped to a link, based on the PPDU format. Specifically, when a station transmits a DL MU PPDU, the station may transmit a frame corresponding to a TID that is not mapped to a link over that link. In this case, the DL MU PPDU may be a DL HE MU PPDU or an EHT PPDU sent to multiple users. The station may also transmit a frame corresponding to any TID that is not mapped to a link over that link.

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

[0178] Figure 19 shows an element that signals information regarding the mapping between a link and a TID according to an embodiment of the present invention.

[0179] The station can signal whether it supports or tolerates the embodiments described with reference to Figures 16-18, because receiving frames corresponding to TIDs other than those mapped to the link may lead to a request for additional action from the station. Specifically, the station can signal whether it can support or tolerate frame transmissions that do not conform to the link-TID mapping when a constraint on the transmission end time applies. When the information indicating whether it can support or tolerate frame transmissions that do not conform to the link-TID mapping indicates a first pre-configured value, that information can indicate that the station will support or tolerate frame transmissions that do not conform to the link-TID mapping when a constraint on the transmission end time applies.

[0180] If the information indicating whether frame transmissions that do not conform to the link-TID mapping can be supported or tolerated shows a second pre-configured value, that information may indicate that the station will not support or tolerate frame transmissions that do not conform to the link-TID mapping. Specifically, if the information indicating whether frame transmissions that do not conform to the link-TID mapping can be supported or tolerated shows a second pre-configured value, that information may indicate that the station will not support or tolerate frame transmissions that do not conform to the link-TID mapping if constraints on the transmission end time apply.

[0181] Furthermore, information indicating whether frame transmissions that do not conform to the link-to-TID mapping can be supported or tolerated may indicate whether the station supports or tolerates transmissions in accordance with the transmission end time limit. In this case, tolerance may indicate whether or not the transmission can be received.

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

[0183] In the embodiments described above, Capabilities elements or Operation elements may be used for signaling. A station can use Capabilities elements or Operation elements to signal whether it can support or tolerate frame transmissions that do not conform to the link-to-TID mapping. A station can also use Capabilities elements or Operation elements to signal the maximum number of TIDs that it can aggregate. Capabilities elements may include EHT Capabilities elements. Operation elements may include EHT Operation elements.

[0184] Figure 19(a) shows a Capabilities element according to one embodiment of the present invention, and Figure 19(b) shows an Operation element according to yet another embodiment of the present invention. The Multi-link multi-TID aggregation support subfield of the Capabilities element can signal to the AP whether a non-AP station will support the station in transmitting frames that do not conform to the link-TID mapping. The Number of TIDs subfield of the Capabilities element indicates the maximum number of TIDs that a station can aggregate. The Permission of Multi-link multi-TID aggregation subfield of the Operation element can indicate whether the AP will allow a non-AP station to transmit frames that do not conform to the link-TID mapping. The Number of TIDs subfield of the Capabilities element can also indicate the maximum number of TIDs that the AP can receive.

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

[0186] When restrictions on the end of transmission apply, whether or not frame transmission that does not conform to the link-to-TID mapping is permitted may be determined on a per-PPDU format basis. If information indicating whether or not frame transmission that does not conform to the link-to-TID mapping is permitted is included in a frame or PPDU, such information may be applied in the response to that frame or PPDU. If information indicating whether or not frame transmission that does not conform to the link-to-TID mapping is permitted is included in a frame or PPDU, such information may be applied within the TXOP (transmit opportunity) that includes that frame or PPDU. The maximum number of TIDs that a station can aggregate may be determined on a per-PPDU format basis. If information indicating the maximum number of TIDs that a station can aggregate is included in a frame or PPDU, such information may be applied in the response to that frame or PPDU. If information indicating the maximum number of TIDs that a station can aggregate is included in a frame or PPDU, such information may be applied in the response to that frame or PPDU. If a frame or PPDU contains information indicating the maximum number of TIDs that stations can gather, that information may be applied within the TXOP containing that frame or PPDU.

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

[0188] In further specific embodiments, the bit following the Reserved subfield of UL HE-SIG-A2 may contain information indicating whether or not to allow frame transmission that does not conform to the link-TID mapping. In further specific embodiments, the information indicating whether or not to allow frame transmission that does not conform to the link-TID mapping may be contained in the bit preceding the Trigger Dependent Common Info field. In further specific embodiments, the information indicating whether or not to allow frame transmission that does not conform to the link-TID mapping may be contained in the User Info field of the trigger frame. Furthermore, embodiments applied to information indicating whether or not to allow frame transmission that does not conform to the link-TID mapping may also be applied to information indicating the maximum number of TIDs that a station can aggregate. The aforementioned Common Info field contains information that applies in common to all stations or TB PPDUs responding to the trigger frame. The User Info field contains information that applies to stations responding with the RU indicated in the User Info field or to the transmitted TB PPDU.

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

[0190] When a station transmits a frame that triggers UL MU transmission, it can perform the channel access described in Figure 6. In this case, AIFS may be determined by the AC, TID, or priority of the traffic the station intends to transmit. Specifically, AIFS may be the product of AIFSN and slot time plus SIFS. When a station intends to transmit relatively high-priority traffic, the length of AIFS may be relatively short. Conversely, when a station intends to transmit relatively low-priority traffic, the length of AIFS may be relatively long. A potential issue is how the station determines the AC, TID, or priority to apply when performing channel access to transmit a station-triggered frame.

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

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

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

[0194] In Figure 20, the AP multilink device includes the first AP (AP1). The first non-AP multilink device (Non-AP MLD 1) includes the first station (STA1). The second non-AP multilink device (Non-AP MLD 2) includes the 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). Link-to-TID mapping is established in Link1. AC_VI and AC_VO are mapped to the link from the first station (STA1) to the first AP (AP1). All TIDs are mapped to the link from the first AP (AP1) to the first station (STA1). Link-to-TID mapping is established in Link2. AC_VO is mapped to the link from the second station (STA2) to the first AP (AP1). Furthermore, all TIDs are mapped to the link from the second AP (AP2) to the first station (STA1). In Figure 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) 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 makes channel access to transmit a frame that triggers a UL MU transmission, the station can make channel access regardless of the link-to-TID mapping. In this case, the station may use any AC. In this case, the link-to-TID mapping may be a link-to-TID mapping to the UL. Alternatively, the link-to-TID mapping may be a link-to-TID mapping in the direction of transmitting the trigger frame.

[0196] As mentioned above, when a station transmits a TB PPDU, the station can transmit frames on that link that correspond to TIDs not mapped to a link. In this way, if a station does not obtain a TXOP through a conflicting procedure, the station can transmit regardless of the link-TID mapping. Also, if a station obtains a TXOP through a conflicting procedure, the station can transmit based on the link-TID mapping. For example, if a station does not obtain a TXOP through a conflicting procedure, the station can transmit frames on that link that correspond to TIDs not mapped to a link. If a station obtains a TXOP through a conflicting procedure, the station can transmit only frames on that link that correspond to TIDs mapped to a link.

[0197] Figure 21 shows the operation of a multilink device transmitting over multiple links according to an embodiment of the present invention.

[0198] As illustrated in the embodiments described using Figures 10 to 15, restrictions may be applied to multilink transmission in relation to the transmission termination time. In a specific embodiment, the multilink device can decide whether or not to apply restrictions related to the transmission termination time based on the frequency interval between links. The degree of internal leakage can vary depending on the frequency interval. If the frequency interval between links is within a predetermined frequency interval, the multilink device may be restricted from simultaneously transmitting and receiving on multiple links. Conversely, if the frequency interval between links is greater than a predetermined frequency interval, the multilink device may not be restricted from simultaneously transmitting or receiving on multiple links.

[0199] Furthermore, restrictions may be applied to the bandwidth used by a multilink device whose STR is limited, or by a multilink device communicating with a multilink device whose STR is limited. Also, in certain circumstances, a multilink device whose STR is limited, or a multilink device communicating with a multilink device whose STR is limited, may use a bandwidth smaller than a certain size.

[0200] In Figure 21, the non-AP multilink device includes a first station (STA1) and a second station (STA2). Each of the first station (STA1) and the second station (STA2) operates on the first link (Link1) and the second link (Link2), respectively. The non-AP multilink device provides limited support for STR. Specifically, the STR of the non-AP multilink device may be limited by the link channel location or bandwidth. In Figure 21, the non-AP multilink device can perform STR when it operates on the P20 channel of the first link (Link1) and the channels of the second link. Also, the non-AP multilink device cannot perform STR when it operates on the S20 channel or S40 channel of the first link (Link1) and the channels of the second link.

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

[0202] The multilink device can make its own decisions regarding the use of the restricted channels described above. Furthermore, in other specific embodiments, the use of restricted channels may be specifically instructed. For example, a frame that triggers UL MU transmission may be assigned a restricted channel. The multilink device may also signal whether STR is possible when a channel is in use. For example, the multilink device may signal whether STR is possible when channels P20, P40, and P80 are in use.

[0203] Figure 22 shows the operation of a multilink device according to an embodiment of the present invention to set the NAV.

[0204] As mentioned above, transmission failures can occur due to internal leakage when transmission and reception are performed simultaneously on multiple adjacent links. In Figure 22, a multilink device transmits on the second link while receiving on the first link. Transmission on the second link can cause the multilink device to fail to receive on the first link. If a station operating on the second link determines that the channel on the second link is idle, that station accesses the channel and transmits. A station operating on the first link (Link 1) sets the NAV (network allocation vector) based on the frame or PPDU transmitted on the first link (Link 1). While other stations are transmitting on the first link (Link 1), the station operating on the first link (Link 1) may determine that the channel is busy based on the NAV. In this way, if the frame or PPDU transmitted on the first link can set the NAV on the second link, the probability of transmission failure due to internal leakage can be reduced. This will be explained using Figures 23 to 26.

[0205] Figure 23 shows the operation of a multilink device according to an embodiment of the present invention to set the NAV.

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

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

[0208] In Figure 23, the multilink device receives on the first link. The duration information received on the first link is transmitted to the second link, and the station operating on the second link sets the NAV based on the transmitted duration information. Since the NAV is set on the station operating on the second link in this way, 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 further specific embodiments, multiple stations included in a multilink device can use Inter-link NAV. Specifically, stations included in a multilink device can access channels based on inter-link NAV, which is a NAV set based on frames or PPDUs exchanged by other stations included in the same multilink device. For example, if a multilink device operates on a first link and a second link, a station operating on the second link can set inter-link NAV based on PPDUs or frames transmitted on the first link. In this case, the station does not need to transmit on the second link based on the set inter-link NAV value. Specifically, the station can determine that the channel on the second link is busy based on the set inter-link NAV value. Also, a multilink device that does not support STR can access channels based on inter-link NAV. In this case, a multilink device that has set inter-link NAV can decide whether or not to access or transmit channels based on inter-link NAV on multiple links or all links on which the multilink device operates.

[0210] In addition, stations can access channels based on a basic NAV in addition to intra-BSS NAV. The basic NAV may be a NAV configured by inter-BSS frames or inter-BSS PPDUs. Furthermore, if a station cannot determine whether a received frame is an inter-BSS frame or an intra-BSS frame, or whether a received PPDU is an inter-BSS PPDU or an intra-BSS PPDU, the station can configure a basic NAV based on the received frame or PPDU.

[0211] As in the above embodiment, when inter-link NAV is configured, even if the configured NAV is reset by transmission on another link, the NAV value configured by the transmission within the link may be maintained. For example, if a multilink device operates on a first link and a second link, one of the stations of the multilink device operating on the second link can configure the NAV based on a PPDU or frame transmitted on the second link. Subsequently, after that station configures the NAV based on a PPDU or frame transmitted on the first link, if the TXOP expires on the first link and the NAV is reset, the NAV may be reset to the NAV configured for transmission on the second link. When inter-link NAV is in operation, the multilink device can maintain the NAV configured for transmission on 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 with inter-link NAV.

[0212] In the embodiments described above, the station setting the NAV may be replaced by the station interrupting channel access or transmission at the physical layer. Alternatively, in the embodiments described above, the station setting the NAV may be replaced by the station determining that the channel is busy. In such cases, the station resetting the NAV may be replaced by the station accessing the channel, transmitting, or determining that the channel is idle. For this purpose, primitives exchanged between the physical layer and the MAC layer may be used. Specifically, primitives that link the MAC layer of one station in the multilink device with the physical layer of another station in the same multilink device may be used. Alternatively, the MAC layer of one station in the multilink device may be linked with the MAC layer of another station in the multilink device.

[0213] Furthermore, if any one station of the multilink device begins receiving a PPDU, the other stations of the multilink device may suspend channel access. As mentioned above, other stations can suspend channel access based on duration information. However, the suspension of channel access may be delayed depending on the location of the field containing the duration information. Therefore, internal leakage may occur if channel access and transmission are performed until the duration information is obtained. Accordingly, as mentioned above, if any one station of the multilink device begins receiving a PPDU, the other stations of the multilink device may suspend channel access. Also, if the intended recipient of the PPDU or the frame contained in the PPDU received by any one station is not that station, the other stations can resume the suspended channel access. This will be explained in detail using Figure 24.

[0214] Figure 24 shows that a station of a multilink device according to an embodiment of the present invention resumes channel access or transmission after interrupting channel access or transmission due to a PPDU received by another station of the multilink device.

[0215] As mentioned above, a station in a multilink device can interrupt channel access or transmission due to a PPDU received by another station in the multilink device. In this case, if the recipient of the PPDU or the frame contained in the PPDU received by the other station is not the other station, 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 interruption of channel access or transmission. If the station fails to obtain duration information from the L-SIG field of the PPDU, the station can resume channel access or transmission. For example, if the station fails to decode the L-SIG field of the PPDU, the station can resume channel access or transmission. Also, if the other station fails to decode the U-SIG field or HE-SIG-A field of the PPDU, the station can resume channel access or transmission. In a specific embodiment, if another station obtains duration information from the U-SIG field or HE-SIG-A field of the PPDU, the station can continue channel access or transmission interruption. Furthermore, if the PHY identifier of the PPDU received by another station is in a PPDU format not supported by the other station, the station can resume channel access or transmission.

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

[0217] Furthermore, if the intended recipient of a PPDU received by another station is not that other station, the station can resume channel access or transmission. If the intended recipient of a PPDU received by another station is that other station, the station can continue to suspend channel access or transmission. If the intended recipient of the received PPDU is that other station, then at least one of the STA-IDs included in the PPDU's EHT-SIG or HE-SIG-B may indicate that other station. Specifically, if the intended recipient of the received PPDU is that other station, then one of the STA-IDs included in the PPDU's EHT-SIG or HE-SIG-B may indicate a group that includes the other station. For example, if one of the STA-IDs is broadcast, then the station can determine that it is the intended recipient of the PPDU received by the other station.

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

[0219] If the intended recipient of a frame contained in a PPDU received by another station is that other station, the station may persist channel access or transmission interruption.

[0220] In the embodiments described above, if a station persists with channel access or transmission interruption, the station can interrupt channel access or transmission until the end of the PPDU received by another station. In such embodiments, the station can quickly resume transmission. In yet another specific embodiment, if a station persists with channel access or transmission interruption, the station can interrupt channel access or transmission until the TXOP duration. In such embodiments, the station can more reliably protect frame exchange sequences occurring on other links. In this case, the TXOP duration can be obtained from the signaling field of the PPDU or the Duration / ID field of the MAC header.

[0221] The aforementioned channel access or transmission interruption / resumption 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 by the PPDU format and frame format. For example, as shown in Figure 24, if the received PPDU is an EHT PPDU, the other station can sequentially decode the L-SIG, U-SIG, EHT-SIG, and MAC header. Also, if the received PPDU is an HE SU PPDU or HE TB PPDU, the other station can sequentially decode the L-SIG, HE-SIG-A, and MAC header. Also, if the received PPDU is an HE MU PPDU, the other station can sequentially decode the L-SIG, HE-SIG-A, HE-SIG-B, and MAC header. Also, if the received PPDU is an 11a / g PPDU, the other station can sequentially decode the L-SIG and MAC header.

[0222] The intended recipient of the aforementioned PPDU or frame may include the intended recipient of the RU from which the PPDU is transmitted. Furthermore, the identifier used to determine whether a recipient is the intended recipient may be a value determined based on the station's AID or MAC address. Additionally, the identifier used to determine whether a recipient is the intended recipient may be an identifier representing a single station.

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

[0224] When a station sends a response to a frame that triggers a UL MU transmission, the station does not need to consider the intra-BSS NAV and the aforementioned inter-link NAV. Specifically, when a station sends a response to a frame that triggers a UL MU transmission sent from a BSS containing the station, the station does not need to consider the intra-BSS NAV and the aforementioned inter-link NAV. When a station sends a response to a frame that triggers a UL MU transmission sent by a multilink device containing the station in the BSS containing the station, the station does not need to consider the intra-BSS NAV and the aforementioned inter-link NAV. In this case, the station may be an AP.

[0225] When a station receives a trigger frame from a multilink device that includes a station that sent a frame with the currently configured intra-BSS NAV or inter-link NAV, and sends a response to the trigger frame, the station does not need to consider intra-BSS NAV or inter-link NAV. Similarly, when a station receives a trigger frame from a station that sent a frame with the currently configured intra-BSS NAV or inter-link NAV, and sends a response to the trigger frame, the station does not need to consider intra-BSS NAV or inter-link NAV.

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

[0227] In these embodiments, even if the AP multilink device sets NAV on the non-AP multilink device, the AP multilink device can still trigger transmission from the non-AP multilink device. Therefore, the AP multilink device can increase network efficiency.

[0228] In the embodiment shown in Figure 25, the non-AP multilink device includes a first station (STA1) and a second station (STA2). Each of the first station (STA1) and the second station (STA2) operates on the first link (Link1) and the second link (Link2), respectively. The second station (STA2) sets the NAV based on the PPDU or frame transmitted to the first station (STA1). At this time, 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 from an AP included in a multilink device that includes an AP associated with the second station (STA2), the second station (STA2) transmits a response to the trigger frame without considering the NAV set on the second station (STA2).

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

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

[0231] While the above description has focused on embodiments, these are merely illustrative and do not limit the present invention. Anyone with ordinary skill in the art to which the present invention belongs will understand that various modifications and applications not exemplified above are possible, as long as they do not deviate from the essential characteristics of these embodiments. For example, each component specifically shown in the embodiments can be modified and implemented. Such differences related to modifications and applications should be interpreted as being within the scope of the present invention as defined in the attached claims. [Explanation of Symbols]

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

Claims

1. A multilink device using multiple links, Transceiver and receiver unit and Including the processor, The aforementioned processor, A multilink device that determines the end time of transmission of multiple PPDUs based on whether or not the multilink device transmits an ACK frame when the multilink device transmits multiple PPDUs simultaneously over multiple links using the transmitting / receiving unit.

2. The aforementioned processor, The multilink device according to claim 1, wherein when the multilink device transmits multiple PPDUs simultaneously over multiple links, it aligns the ends of multiple PPDUs that request ACK from among the multiple PPDUs.

3. The aforementioned processor, The multilink device according to claim 1, wherein when the multilink device transmits multiple PPDUs simultaneously over multiple links, the end of a PPDU containing only frames that do not request an ACK is not aligned with the end of a PPDU containing frames that request an ACK.

4. The aforementioned processor, The multilink device according to claim 3, wherein when the multilink device transmits multiple PPDUs simultaneously over multiple links, the termination of a PPDU containing only frames that do not request an ACK is delayed compared to the termination of a PPDU containing frames that request an ACK.

5. The multilink device according to claim 1, wherein whether or not a frame requests ACK is determined based on an ACK policy.

6. The multilink device according to claim 5, wherein the frame requesting ACK is a data frame.

7. The aforementioned multilink device is an AP multilink device, The aforementioned processor, The multilink device according to claim 1, wherein the transmitting and receiving unit is used to transmit the plurality of PPDUs to a non-AP multilink device.

8. The multilink device for receiving the plurality of PPDUs is such that when transmission is performed on one link, reception is not possible on the other links, as described in claim 1.

9. A multilink device using multiple links, Transceiver and receiver unit and Including the processor, The aforementioned processor, The multilink device uses the transmitting and receiving unit to simultaneously receive multiple PPDUs on multiple links. A multilink device in which the end time of transmission for the multiple PPDUs is determined based on whether or not a frame requesting ACK is transmitted by the multiple PPDUs.

10. The multilink device according to claim 9, wherein the ends of the plurality of PPDUs requesting ACK are aligned among the plurality of PPDUs.

11. The multilink device according to claim 9, wherein the end of a PPDU containing only frames that do not request ACK among the plurality of PPDUs is not aligned with the end of a PPDU containing frames that request ACK among the plurality of PPDUs.

12. The multilink device according to claim 11, wherein the termination of a PPDU containing only frames that do not request ACK among the plurality of PPDUs is not later than the termination of a PPDU containing frames that request ACK among the plurality of PPDUs.

13. The multilink device according to claim 9, wherein whether or not a frame requests ACK is determined based on an ACK policy.

14. The multilink device according to claim 13, wherein the frame requesting ACK is a data frame.

15. The aforementioned multilink device is a non-AP multilink device. The aforementioned processor, The multilink device according to claim 9, wherein the AP multilink device transmits the plurality of PPDUs using the receiving unit.

16. The multilink device according to claim 9, wherein when transmission is performed on one link, reception is not possible on the other links.

17. The aforementioned processor, The channel is accessed using a channel access method that employs a backoff counter across the aforementioned multiple links. The backoff counter is initially set to a value by an acquired random number, decreases by 1 each time the channel to be accessed is idle during the slot time, and when the value of the backoff counter is 0, the terminal is permitted to access the channel. The multilink device according to claim 16, wherein transmission is not performed on any of the links if the backoff counter reaches zero during channel access on any one of the links.

18. The aforementioned processor, The multilink device according to claim 17, wherein the value of the backoff counter is maintained when no transmission is performed on any one of the aforementioned links.

19. A method for operating a multilink device using multiple links, The multilink device includes the step of receiving multiple PPDUs simultaneously on multiple links using the transmitting and receiving unit, An operation method in which the end time of transmission for the multiple PPDUs is determined based on whether or not a frame requesting ACK is transmitted by the multiple PPDUs.

20. The operation method according to claim 19, wherein the ends of the plurality of PPDUs requesting ACK are aligned among the plurality of PPDUs.

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