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

Abstract

To provide a multi-link device using a plurality of links.SOLUTION: A processor is configured to: receive, in any one of the links, a first physical layer protocol data unit (PPDU) including access category (AC) constraint signaling and a reverse direction (RD) grant from a station which is a transmission opportunity (TXOP) holder or a service period (SP) source; and transmit, in the one link, a second PPDU to the station in response to the first PPDU on the basis of the AC constraint signaling. The AC constraint signaling indicates whether a traffic identifier (TID) or AC of a frame included in the second PPDU is constrained.SELECTED DRAWING: Figure 13

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, as the spread of mobile devices has expanded, wireless LAN (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 at home, in enterprises, or in 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 uses OFDM (Orthogonal Frequency Division Multiplexing) 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 achieve 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] A multilink device using multiple links according to one embodiment of the present invention includes a transmitting / receiving unit and a processor. The processor receives a first PPDU (physical layer protocol data unit) including AC (access category) restriction signaling and RD (reverse direction) grant from a station which is a TXOP (transmission opportunity) holder or SP (service period) source on any one of the multiple links, and transmits a second PPDU to the station on any one of the links as a response to the first PPDU based on the AC restriction signaling. The AC restriction signaling indicates whether the TID (traffic identifier) ​​or AC of the frame included in the second PPDU is restricted.

[0010] An AC or TID is mapped to one of the multiple links, and the multilink device can transmit a frame on any one of the links based on the mapped AC or TID. In this case, the processor indicates that the AC limiting signaling is acceptable for any TID of the data frame included in the second PPDU, and when the multilink device includes a data frame in the second PPDU, it may exclude data frames corresponding to TIDs not mapped to any of the links, and include data frames corresponding to TIDs mapped to any of the links in the second PPDU.

[0011] An AC or TID is mapped to one of the multiple links, and the multilink device can transmit a frame on any one of the links based on the mapped AC or TID. At this time, the processor indicates that the AC limiting signaling is limiting the AC or TID of the frame included in the second PPDU, and when the multilink device includes a data frame in the second PPDU, it may not include a data frame in the second PPDU that is not mapped to any of the links or that corresponds to a TID or AC with a lower priority than the AC or TID of the frame received from the station, but may include a data frame in the second PPDU that is mapped to any of the links and corresponds to a TID or AC with the same priority as or higher than the AC or TID of the frame received from the station.

[0012] When the multilink device receives multiple frames from the station, the AC or TID priority of the frame received from the station may be the lowest priority among the multiple frames.

[0013] The aforementioned processor can consider the AC of the management frame to be a predetermined value.

[0014] If the multilink device includes a BlockAck frame in the second PPDU, the processor can determine the AC of the BlockAck frame based on the TID field of the BlockAck frame. Also, if the multilink device includes a BlockAckReq frame in the second PPDU, the processor can determine the AC of the BlockAckReq frame based on the TID field of the BlockAckReq frame.

[0015] The aforementioned AC restriction signaling may be included in the MAC (medium access control) header of the frame included in the PPDU containing the RD grant.

[0016] An embodiment of the present invention provides a method for operating a multilink device using multiple links, comprising the steps of: receiving a first PPDU (physical layer protocol data unit) including AC (access category) restriction signaling and RD (reverse direction) grant from a station which is a TXOP (transmission opportunity) holder or SP (service period) source on one of the multiple links; and transmitting a second PPDU to the station on one of the links as a response to the first PPDU based on the AC restriction signaling. The AC restriction signaling indicates whether the TID (traffic identifier) ​​or AC of the frame contained in the second PPDU is restricted.

[0017] An AC or TID is mapped to one of the multiple links, and the multilink device can transmit frames based on the AC or TID mapped to any one of the links. In this case, the step of transmitting the second PPDU to the station may include the step of the AC limiting signaling indicating that any TID of the data frame included in the second PPDU is acceptable, and when the multilink device includes a data frame in the second PPDU, it may include a step of not including a data frame corresponding to a TID not mapped to any of the links in the second PPDU, but including a data frame corresponding to a TID mapped to any of the links in the second PPDU.

[0018] An AC or TID is mapped to one of the multiple links, and the multilink device can transmit frames on any one of the links based on the mapped AC or TID. In this case, the step of transmitting the second PPDU to the station may include the step of not including in the second PPDU data frames that are not mapped to any of the links or that have a lower priority TID or AC than the priority of the AC or TID of the frame received from the station, and including in the second PPDU data frames that are mapped to any of the links and have a priority TID or AC that is the same as or higher than the priority of the AC or TID of the frame received from the station.

[0019] When the multilink device receives multiple frames from the station, the AC or TID priority of the frame received from the station may be the lowest priority among the multiple frames.

[0020] The step of transmitting the second PPDU to the station may include the step of regarding the AC of the management frame as a predetermined value in advance.

[0021] The step of transmitting the second PPDU to the station may include the step of determining the AC of the BlockAck frame based on the TID field of the BlockAck frame when the multi-link device includes the BlockAck frame in the second PPDU, and the step of determining the AC of the BlockAckReq frame based on the TID field of the BlockAckReq frame when the multi-link device includes the BlockAckReq frame in the second PPDU. The AC restriction signaling may be included in the MAC (medium access control) header of the frame included in the PPDU including the RD grant.

Advantages of the Invention

[0022] One embodiment of the present invention provides a wireless communication method for efficiently using multi-link and a wireless communication terminal using the same.

Brief Description of the Drawings

[0023] [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 the process of a STA setting 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]Examples of various standard generational PPDU (PLCP Protocol Data Unit) formats are shown. [Figure 8] 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 are shown. [Figure 9] This shows a multi-link device according to an embodiment of the present invention. [Figure 10] This example illustrates frame exchange between a non-AP multilink device and an AP multilink device when TID-to-link mapping is configured according to an embodiment of the present invention. [Figure 11] This example demonstrates frame exchange following a reverse direction (RD) protocol according to an embodiment of the present invention. [Figure 12] This shows an AC restriction signaling according to an embodiment of the present invention. [Figure 13] The frame format and the signaling field format of the frame according to an embodiment of the present invention are shown. [Figure 14] One embodiment of the present invention demonstrates that RD exchanges are performed without AC restrictions on links to which TID-to-link mapping is applied. [Figure 15] A further embodiment of the present invention demonstrates that RD exchanges are performed without AC limitations on links to which TID-to-link mapping is applied. [Figure 16] A further embodiment of the present invention demonstrates that AC limits are not set when RD exchanges occur on a link to which TID-to-link mapping is applied. [Figure 17] A further embodiment of the present invention demonstrates that RD replacement occurs when AC restriction is applied on a link to which TID-to-link mapping is applied. [Figure 18]A further embodiment of the present invention demonstrates that RD replacement occurs when AC restriction is applied on a link to which TID-to-link mapping is applied. [Figure 19] Embodiments of the present invention demonstrate the signaling of information regarding AC limits used in the RD initiator RD response. [Figure 20] An embodiment of the present invention demonstrates that RD exchange occurs when a PPDU with synchronized transmission termination is transmitted across multiple links. [Figure 21] This document shows the RU configuration that can be assigned to a single station in IEEE 802.11ax and the RU configuration that can be assigned to a single station according to an embodiment of the present invention. [Figure 22] The IEEE 802.11ax standard and the OFDMA DL PPDU used in the embodiment of the present invention are shown. [Figure 23] This embodiment of the present invention demonstrates that the backoff procedure is performed using subchannels other than the 20MHz main channel. [Figure 24] An embodiment of the present invention demonstrates that when a station successfully accesses a channel on a subchannel other than the 20MHz main channel and transmits a PPDU, the length of the PPDU is limited. [Figure 25] An embodiment of the present invention demonstrates that when the 20MHz main channel is not idle, a station accesses the channel via a subchannel of a segment other than the main segment. [Figure 26] An embodiment of the present invention demonstrates that the first AP of a multilink device signals via the second AP that the first AP can receive on a subchannel other than the 20 MHz main channel. [Figure 27] This embodiment of the present invention demonstrates that the AP of an AP multilink device allows a station parked on a segment other than the 80MHz main channel to perform a backoff procedure for uplink transmission on the segment in which the station is parked. [Modes for carrying out the invention]

[0024] 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.

[0025] 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.

[0026] In the present invention, the terms "field" and "subfield" may be used interchangeably.

[0027] Figure 1 shows a wireless LAN system according to one embodiment of the present invention.

[0028] 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.

[0029] 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.

[0030] 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).

[0031] 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.

[0032] 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).

[0033] 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.

[0034] 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.

[0035] 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.

[0036] First, the communication unit 120 transmits and receives wireless signals such as wireless LAN packets and may be incorporated into the station 100 or provided externally. 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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-described 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] Figure 5 is a schematic diagram illustrating the process by which STA establishes a link with AP.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] Figure 6 shows the CSMA (Carrier Sense Multiple Access) / CA (Collision Avoidance) method used in wireless LAN communication.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] <Examples of various PPDU formats>

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061]

number

[0062] At this time,

[0063]

number

[0064] x represents the smallest natural number greater than or equal to x. Since the maximum value of the L_LENGTH field is 4095, the length of the PPDU may be set to a maximum of 5.484 ms. Non-legacy terminals sending the PPDU must set the L_LENGTH field as shown in Equation 2 below.

[0065]

number

[0066] 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.

[0067]

number

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] For the sake of clarity, the terms frame or MAC frame may be used interchangeably with MPDU in this specification.

[0091] 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.

[0092] Figure 9 shows a multi-link device according to an embodiment of the present invention.

[0093] 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.

[0094] 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.

[0095] 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).

[0096] 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).

[0097] 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.

[0098] 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.

[0099] Furthermore, a mapping between TID (traffic identifier) ​​and links may be established. This will be explained using Figure 10.

[0100] Figure 10 shows the frame exchange between a non-AP multilink device and an AP multilink device when TID-to-link mapping is set up according to an embodiment of the present invention.

[0101] Specifically, frames corresponding to a particular 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 the first TID to multiple first links, and the second multilink device may be configured to send frames with the second TID to the first links. Furthermore, 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 the TID 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] When a link is mapped to a TID or AC, frames may be transmitted on that link based on the TID or AC mapped to that link. Specifically, when a link is mapped to a TID or AC, only frames corresponding to the TID or AC mapped to that link may be transmitted on that link. 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, ACKs 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 specific link.

[0106] In the embodiment shown in Figure 10, 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 first AP (AP1) and the first station (STA1) are associated by a first link (Link1), and the second AP (AP2) and the second station (STA2) are associated by a second link (Link2). All TIDs are mapped to the first link (Link1), and AC_VO or TIDs corresponding to AC_VO are mapped to the second link (Link2). In such a case, all TIDs may be exchanged in the first link (Link1), and TIDs corresponding to AC_VO may be exchanged in the second link (Link2). Furthermore, the exchange of data that does not correspond to AC_VO may not be permitted in the second link (Link2).

[0107] The aforementioned mapping of TIDs to links may ensure QoS. Specifically, a relatively small number of stations may be operating, or high-priority ACs or TIDs may be mapped to links with good channel conditions. Furthermore, the aforementioned mapping of TIDs to links may allow stations to maintain a power-saving state for a longer period of time.

[0108] Figure 11 shows frame exchange following a reverse direction (RD) protocol according to an embodiment of the present invention.

[0109] In embodiments of the present invention, frames may be exchanged according to a reverse direction protocol. Specifically, a station that is a TXOP (transmit opportunity) holder may transmit a frame to a responder, and the responder may transmit a frame to a station that is a TXOP holder. When a station that is not a TXOP holder receives an RD grant (RDG) from a station that is a TXOP holder, the station that is not a TXOP holder may transmit a frame to the station that is a TXOP holder within that TXOP. That is, the station that receives the RDG may transmit a frame to the station that is a TXOP holder without a separate conflict procedure-based channel access or backoff procedure. In this case, the station that transmits the RDG may be called the RD initiator, and the station that receives the RDG may be called the RD responder. Furthermore, the exchange of frames according to the RD protocol may be called an RD exchange or an RD exchange sequence. HT stations, VHT stations, HE stations, EHT stations, DMG stations, and S1G (Sub 1 GHz) stations can assist in RD exchange.

[0110] A station can signal whether or not it can operate as an RD responder. Specifically, a station can signal whether or not it can operate as an RD responder using a subfield of the HT Extended Capabilities field of the HE Capabilities element. In this case, the subfield can be called the RD Responder field. In yet another specific embodiment, a station can signal whether or not it can operate as an RD responder using the 6GHz Band Capabilities element or a subfield of the 6GHz Band Capabilities element. If a station signals that it cannot operate as an RD responder, it is not permissible to send an RD grant to the station.

[0111] A station can signal information regarding RD exchange using at least one of the RDG / More PPDU subfield and the AC constraint subfield. In this case, the RDG / More PPDU subfield and the AC constraint subfield may be included in the HTC field. The HTC field may be a high throughput control field. A frame containing the HTC field may be called a +HTC frame. An MPDU corresponding to a frame containing the HTC field may be called a +HTC MPDU. The CAS Control subfield may contain at least one of the RDG / More PPDU subfield and the AC Constraint subfield.

[0112] RD replacement may be performed as follows:

[0113] An RD initiator can send a PPDU containing an RDG to an RD responder. In this case, the RD initiator may be a TXOP holder or a Service Period (SP) source. Whether or not an RDG is included may be signaled by the RDG / More PPDU subfield described above. When the value of the RDG / More PPDU subfield is 1, the RDG / More PPDU subfield indicates that the PPDU containing the RDG / More PPDU subfield contains an RDG. When the value of the RDG / More PPDU subfield is 0, the RDG / More PPDU subfield indicates that the PPDU containing the RDG / More PPDU subfield does not contain an RDG.

[0114] A station that receives an RDG can transmit a PPDU immediately after the PPDU containing the RDG. That is, a station that receives an RDG can transmit a PPDU without separate conflicting procedure-based channel access. In this case, the interval between the PPDU containing the RDG and the PPDU transmitted by the station that received the RDG may be SIFS (short interframe space) or RIFS (reduced interframe space). In this specification, "immediately after" and "immediately after" can represent a predetermined time interval. In this case, the predetermined time interval may be SIFS or RIFS.

[0115] In these embodiments, a station that receives an RDG can send a PPDU to the RD initiator. That is, the PPDU sent by a station that receives an RDG may include a frame to which the RD initiator is the intended recipient. Furthermore, a station that receives an RDG can send multiple PPDUs. One or more PPDUs sent by a station that receives an RDG after receiving a PPDU containing an RDG can be called an RD response or an RD response burst. A station that receives an RDG and sends PPDUs, i.e., an RD response or a station that sends an RD response, can be called an RD responder. As mentioned above, an RD responder can send multiple PPDUs in succession after receiving an RDG. An RD responder can send one PPDU and then immediately send another PPDU. In this case, the RD responder can signal in the frame contained in the PPDU whether or not another PPDU will be sent immediately after the PPDU containing the frame. That is, the RD responder can signal in the frame contained in the PPDU whether or not another PPDU will be sent at an interval of SIFS or RIFS between the PPDU containing the frame and the PPDU containing the frame. In this case, the aforementioned RDG / More PPDU subfield may be used. Specifically, the RDG / More PPDU subfield sent by the RD initiator can indicate the RDG, and the RDG / More PPDU subfield sent by the RD responder can indicate whether an additional PPDU is sent after the PPDU containing the RDG / More PPDU. Furthermore, an RD response may contain at most one immediate BlockACK frame or ACK frame.

[0116] Upon receiving an RD response, the RD initiator can send an ACK (acknowledgment) to the RD responder. Specifically, the RD initiator can send an ACK to the RD responder immediately after receiving the RD response.

[0117] A single TXOP or SP may contain multiple RD exchange sequences. In this case, the RD initiators of the multiple RD exchange sequences may be the same, while the RD responders of the multiple RD exchange sequences may be different. In such an embodiment, one RD responder can participate in multiple RD exchange sequences.

[0118] An RD responder can send a PPDU to multiple stations as an RD response. For example, if the RD responder is a VHT AP, the RD response may include a VHT MU PPDU. If the RD responder is an HE AP, the RD response may include an HE MU PPDU. If the RD responder is an EHT AP, the RD response may include an EHT MU PPDU. The RD responder can also send an RD response that includes a trigger frame. In this case, the trigger frame may be limited to a trigger frame that triggers the RD initiator's transmission. In this specification, a trigger frame may represent a frame that includes a TRS (triggered response scheduling) field in addition to a trigger frame. A station that receives a trigger frame can send a trigger-based (TB) PPDU as a response to the PPDU containing the trigger frame. In this case, the interval between the PPDU containing the trigger frame and the TB PPDU may be SIFS.

[0119] The AC or TID of frames that an RD responder can send in an RD response may be restricted. In this case, the RD initiator can signal whether or not the AC or TID of frames that an RD responder can send in an RD response or RD response burst is restricted. Specifically, the RD initiator can use the AC Constraint subfield to signal whether or not the AC or TID of frames that an RD responder can send in an RD response is restricted. Also, if the RD initiator obtains a TXOP via EDCA (enhanced distributed channel access), the AC or TID of frames that an RD responder can send in an RD response may be restricted. The RD initiator is not permitted to request frames other than ACK (acknowledgment) frames from the RD responder. Therefore, the RD initiator does not need to request frames other than ACK (acknowledgment) frames from the RD responder. In this case, the ACK (acknowledgment) frame may include at least one of the following: an ACK frame, a compressed BlockAck frame, an Extended Compressed Block frame, and a Multi-STA BlockAck frame.

[0120] If the RD responder signals that it will not send an additional PPDU, the RD initiator may send a PPDU immediately after the RD response. Specifically, if the RD initiator receives a frame from the RD responder that may contain an HT control field, and the frame does not contain an HT control field, the RD initiator may send a PPDU immediately after the RD response. In yet another specific embodiment, if the RD initiator receives a frame from the RD responder requesting an immediate response, the RD initiator may send a PPDU immediately after the RD response.

[0121] Furthermore, if the RD initiator fails to receive an RD response to a PPDU containing an RDG, the RD initiator can send a PPDU. Specifically, if the RD initiator fails to receive a response to a PPDU containing an RDG within a predetermined time, the RD initiator can send a PPDU after a predetermined time has elapsed since the PPDU containing the RDG was sent. Specifically, the RD initiator can send a PPDU after PIFS from the time the PPDU containing the RDG was sent. In addition, the RD initiator can perform channel sensing before sending a PPDU and only send a PPDU if the channel is idle. This may be part of the RD initiator's error recovery operation.

[0122] RD responders can provide RD responses under the following conditions:

[0123] Furthermore, when an RD responder sends an RD response, they can send the RD response regardless of the configured NAV (network allocation vector).

[0124] Furthermore, an RD responder can only make an RD response within the TXOP or SP obtained by the RD initiator. An RD responder can obtain the TXOP duration or SP duration from the MAC header of the frame contained in the PPDU containing the RDG. Specifically, an RD responder can obtain the TXOP duration or SP duration from the Duration / ID field of the MAC header of the frame contained in the PPDU containing the RDG.

[0125] Furthermore, the frames that an RD responder can send as an RD response may be restricted. Specifically, the frames that an RD responder can send as an RD response may be restricted to frames for ACK (acknowledgement), QoS data frames, QoS Null frames, management frames, and basic trigger frames. In this case, frames for ACK (acknowledgement) may include at least one of the following: ACK frames, compressed BlockAck frames, Extended Compressed Block frames, and Multi-STA BlockAck frames.

[0126] Furthermore, the intended recipient of at least one frame included in the RD response may be limited to the RD initiator. The intended recipient of a frame may be indicated by its MAC address. Specifically, the station corresponding to the MAC address indicated by the Address1 field of the frame may be the intended recipient of the frame. In yet another specific embodiment, the station that triggers the transmission of the trigger frame may be the intended recipient of the trigger frame.

[0127] Furthermore, when an RD responder sends an RD response, they can only send PPDUs with a channel width equal to or smaller than the channel width of the PPDU containing the RDG. In this case, the RD responder can determine the channel width of the PPDU containing the RDG from the CH_BANDWIDTH value of the RXVECTOR obtained when receiving the PPDU containing the RDG.

[0128] When a PPDU containing an RDG requests an immediate block ACK response, the RD responder may include a BlockAck frame in the first PPDU of the RD response. As mentioned above, when an RD responder sends multiple PPDUs as an RD response, the RD responder may signal that additional PPDUs will be sent in PPDUs other than the last PPDU of the RD response. Specifically, the RD responder may set the value of the RDG / More PPDU field of PPDUs other than the last PPDU of the RD response to indicate that additional PPDUs will be sent. Alternatively, the RD responder may set the value of the RDG / More PPDU field of PPDUs other than the last PPDU of the RD response to indicate that no additional PPDUs will be sent. In this case, a value of 1 in the RDG / More PPDU field can indicate that additional PPDUs will be sent, and a value of 0 in the RDG / More PPDU field can indicate that no additional PPDUs will be sent. Furthermore, it is not permissible for an RD responder to send additional PPDUs after sending a PPDU containing a frame requesting an immediate response. Therefore, when an RD responder sends a PPDU containing a frame requesting a response, it can signal that no additional PPDUs will be sent. Furthermore, after an RD responder signals that no additional PPDUs will be sent, the RD responder is not required to send additional PPDUs as an RD response.

[0129] When an RD responder sends a trigger frame, the RD responder can configure the fields of the trigger frame so that channel sensing is not required when responding to the trigger frame. Specifically, the RD responder can set the CS Required field of the trigger frame to 1. In this case, the trigger frame may be a basic trigger frame.

[0130] As mentioned above, the TID or AC of frames included in the PPDU sent by the RD responder as an RD response may be restricted. If the RD initiator signals that the AC or TID of frames that the RD responder can send is restricted, the RD responder may include frames with the same AC as the frame containing the RDG in the PPDU of the RD response. Specifically, if the RD initiator sets the RDG / More subfield to 1 and the value of the AC constraint subfield to 1, the RD responder may include frames with the same AC as the frame containing the RDG in the PPDU of the RD response. Also, if the RD initiator signals that the AC or TID of frames that the RD responder can send is restricted, the RD responder may set the Preferred AC subfield of the trigger frame included in the RD response to indicate the same AC as the frame containing the RDG. The Preferred AC subfield can indicate a recommendation for the AC of the MPDU included in the PPDU sent as a response to a frame containing the Preferred AC subfield. Specifically, the Preferred AC subfield can indicate the lowest priority AC among those recommended as the AC for the MPDU included in the PPDU sent as a response to a frame containing the Preferred AC subfield. As mentioned above, the Preferred AC subfield may be included in the trigger frame. Specifically, the Preferred AC subfield may be included in the basic trigger frame.

[0131] In the embodiment shown in Figure 11, the first station (STA A) is the RD initiator. The second station (STA B) and the third station (STA C) may be RD responders. In the embodiment shown in Figure 11, eight PPDU exchanges occur during TXOP.

[0132] In the first PPDU exchange (a), Station 1 (STA A) sends a PPDU containing a QoS data frame to Station 2 (STA B), which is the intended recipient. The Ack Policy field of the QoS data frame, which specifies the response rule for the data frame, may be set to implicit BlockAck Request, indicating that an immediate response using a BlockAck frame is required. The RDG / More PPDU subfields of the two QoS data frames included in the PPDU indicate the RDG. The Duration / ID field of the QoS data frame indicates the duration of the remaining TXOP.

[0133] In the second PPDU exchange (b), Station 2 (STA B) sends a PPDU containing a BlockAck frame, which is a +HTC frame, to Station 1 (STA A). The value of the RDG / More PPDU field in the BlockAck frame is set to 1, signaling that an additional PPDU will be sent immediately after the PPDU containing the BlockAck frame is sent.

[0134] In the third PPDU exchange (c), the second station (STA B) sends a PPDU containing a QoS data frame to the first station (STA A). At this time, the second station (STA B) sets the RDG / More PPDU subfield value of the QoS data frame to 0, signaling that no additional PPDUs will be sent immediately after sending the PPDU containing the BlockAck frame.

[0135] In the fourth PPDU exchange (d), Station 1 (STA A) regains control of the TXOP. Station 1 (STA1) sends a PPDU containing a BlockAck frame to Station 2 (STA B). At this time, the BlockAck frame may contain ACKs for the QoS data frames sent in the second and third PPDU exchanges.

[0136] In the fifth PPDU exchange (e), Station 1 (STA A) sends a PPDU containing a QoS data frame intended for Station 3 (STA C). The Ack Policy field of the QoS data frame may be set to implicit BlockAck Request. Station 1 (STA A) also signals RDG by setting the RDG / More PPDU subfields of the two QoS data frames contained in the PPDU to 1. The Duration / ID field of the QoS data frame indicates the duration of the remaining TXOP.

[0137] In the sixth PPDU exchange (f), the third station (STA C) sends a PPDU to the first station (STA A) that includes a BlockAck frame (which is a +HTC frame) and a QoS data frame. At this time, the third station (STA C) sets the Ack policy field of the QoS data frame to implicit BlockAck Request. The third station (STA C) also sets the RDG / More PPDU subfield value of the QoS data frame to 0, signaling that no additional PPDUs will be sent immediately after sending the PPDU containing the BlockAck frame.

[0138] In the seventh PPDU exchange (g), Station 1 (STA A) regains control of the TXOP. Station 1 (STA A) sends a PPDU containing a BlockAck frame to Station 3 (STA C). The BlockAck frame may contain an ACK for the QoS data frame sent in the sixth PPDU exchange. Station 1 (STA A) signals RDG by setting the RDG / More PPDU subfield of the BlockAck frame contained in the PPDU to 1.

[0139] In the eighth PPDU exchange (h), the third station (STA C) sends a PPDU containing two QoS data frames, which are +HTC frames, to the first station (STA A). At this time, the third station (STA C) sets the Ack policy field of the QoS data frame to implicit BlockAck Request. The third station (STA C) also sets the RDG / More PPDU subfield value of the QoS data frame to 0, signaling that no additional PPDUs will be sent immediately after sending the PPDU containing the BlockAck frame.

[0140] In the ninth PPDU exchange (i), Station 1 (STA A) sends Station 3 (STA C) a PPDU containing a BlockAcK frame that includes an ACK for the QoS data frame sent in the eighth PPDU exchange.

[0141] We have already explained that in the RD protocol, the AC or TID of frames included in the PPDU sent as an RD response is restricted. This may be to ensure fairness with other stations, as a TXOP holder may acquire a TXOP using channel access parameters corresponding to a specific AC. Figure 12 will be used to specifically explain this restriction on the AC or TID of frames included in the PPDU sent as an RD response. For the sake of explanation, we will refer to this restriction on the AC or TID of frames included in the PPDU sent as an RD response as an AC restriction (Constraint).

[0142] Figure 12 shows an AC limiting signaling according to an embodiment of the present invention.

[0143] AC restriction signaling can indicate that the TID of a data frame included in the RDG response PPDU is not restricted. That is, AC restriction signaling can signal that the RDG response PPDU may include a data frame with any TID. Alternatively, AC restriction signaling can indicate that the AC or TID of a frame included in the RDG response PPDU may be restricted. Specifically, AC restriction signaling may indicate that the AC or TID of a frame included in the RDG response PPDU may be restricted to an AC or TID value specified by the RD initiator. In yet another specific embodiment, AC restriction signaling can indicate that the AC or TID of a data frame included in the RDG response PPDU is restricted to a value set based on the TID or AC of the frame received from the RD initiator. For example, AC restriction signaling can indicate that the AC or TID of a data frame included in the RDG response PPDU is restricted to the TID or AC of the frame received from the RD initiator. Furthermore, AC restriction signaling can indicate that the AC or TID of a frame included in the RDG response's PPDU is restricted to a TID or AC with the same priority as, or a higher priority than, the TID or AC of a frame received from the RD initiator. In such an embodiment, the frame received from the RD initiator may represent the last frame received from the RD initiator. In yet another specific embodiment, when an RD responder receives multiple frames from the RD initiator, the frame received from the RD initiator may represent the TID or AC with the lowest priority among the TIDs or ACs of the frames received from the RD initiator.

[0144] An RD responder may consider the AC of a management frame to be a pre-specified value. In this case, the pre-specified value may be AC_VO. Furthermore, an RD responder may determine the AC of a BlockAckReq frame based on the TID field of the BlockAckReq frame, and determine the AC of a BlockAck frame to be the basis indicated by the TID field of the BlockAck frame. Specifically, an RD responder may determine the AC of a BlockAckReq frame to be the AC of the TID indicated by the TID field of the BlockAckReq frame, and the AC of a BlockAck frame to be the AC of the TID indicated by the TID field of the BlockACk frame. In this case, the TID fields of the BlockACk frame and BlockACkReq frame may indicate the TID to which the Ack is sent. Also, when an RD initiator sends a frame for which the AC cannot be determined, the RD initiator is not permitted to set the RDG for that frame. Specifically, when an RD initiator sends a frame for which AC cannot be determined, the RD initiator is not permitted to set the RDG / More PPDU field of that frame to 1.

[0145] AC restriction signaling may be indicated by the AC Constraint subfield described above. Specifically, when the value of the AC Constraint subfield is 0, the AC Constraint subfield can indicate that the TID of the data frame included in the PPDU of the RDG response is not restricted. Also, when the value of the AC Constraint subfield is 1, the AC Constraint subfield can indicate that the TID or AC of the frame included in the PPDU of the RDG response is restricted.

[0146] In the embodiment shown in Figure 12, the RD initiator sends a QoS data frame that is AC_BE to the RD responder using a PPDU containing RDG. At this time, the RD initiator sets the value of the AC restriction field to 1, indicating that the TID or AC of the data frame included in the RD response PPDU is restricted. Since the TID or AC of the data frame included in the RD response PPDU is restricted, the RD responder includes a QoS data frame corresponding to AC_BE in the RD response PPDU.

[0147] Figure 13 shows the frame format and the signaling field format of the frame according to an embodiment of the present invention.

[0148] Figure 13(a) shows the format of a MAC frame. A MAC frame can include a MAC header, a Frame Body, and an FCS. The MAC header can include at least one of the RDG / More PPDU subfield and the AC Constraint subfield described above.

[0149] Specifically, a MAC header can include the Frame Control field, Duration / ID field, MAC address field, Sequence Control field, QoS Control field, and HT Control field. The Frame Control field can include the Type subfield and Subtype subfield. The Type subfield and Subtype subfield can indicate the frame type and subtype, respectively. The Frame Control field also includes the +HTC subfield, which can indicate whether the frame containing the Frame Control field also contains the HT Control field. The Duration / ID field can indicate the duration. The Duration / ID field indicates the duration if the frame containing the Duration / ID field is not a PS-Poll frame. A station receiving a MAC frame can also configure its NAV based on the duration indicated by the Duration / ID field. The Duration / ID field can indicate an ID, such as AID. The Duration / ID field indicates an ID if the MAC frame containing the Duration / ID field is a PS-Poll frame.

[0150] Furthermore, the MAC address field can contain one or more address fields. The address field indicates the MAC address. The address field can also contain at least one of the following fields: BSSID (basic service set identifier), SA (source address), DA (destination address), TA (transmitting STA address or transmitter address), or RA (receiving STA address or receiver address). The Sequence Control field can indicate the fragment number or sequence number corresponding to the MAC frame containing the Sequence Control field. The QoS Control field can indicate at least one of the following: the TID of the MAC frame containing the QoS Control field, the Ack Policy corresponding to the MAC frame containing the QoS Control field, the TXOP limit, the buffer status of the station sending the MAC frame containing the QoS Control field, or the queue size of the station sending the MAC frame containing the QoS Control field. The QoS Control field can also contain at least one of the aforementioned RDG / More PPDU subfield and AC Constraint subfield. For example, the QoS Control field included in the DMG PPDU can contain the aforementioned RDG / More PPDU subfield and AC Constraint subfield.

[0151] The HT Control field may contain at least one of the aforementioned RDG / More PPDU subfield and AC Constraint subfield. The HT Control field may consist of 4 octets, or 32 bits.

[0152] MAC headers and the fields contained within them can have a predetermined length.

[0153] The Frame Body field contains the content of the MAC frame. For example, the Frame Body field can contain information corresponding to the frame type and subtype.

[0154] The FCS field indicates the frame check sequence (FCS) of the MAC frame containing the FCS field. The value of the FCS field may be the FCS obtained based on the values ​​of the MAC header and Frame Body fields. A station that receives an MAC frame can determine whether or not it successfully received the MAC frame based on the value of the FCS field.

[0155] Figure 13(b) shows the format of the HT Control field. The HT Control field may contain at least one of the AC Constraint subfield and the RDG / More PPDU subfield.

[0156] For example, the HT Control field may consist of 32 bits (B0 to B31). In this case, B30 and B31 may be the AC Constraint subfield and the RDG / More PPDU subfield, respectively. The format of the HT Control field may vary depending on the format of the PPDU containing the HT Control field. First, the HT Control field described above may be an HT variant contained in an HT PPDU, or a VHT variant contained in a VHT PPDU. Furthermore, the format of the HT Control field may include an HE variant contained in an HE PPDU, or an EHT variant contained in an EHT PPDU. In this case, the HE variant can represent a variant of the HT Control field contained in a PPDU introduced in versions of the 802.11ax standard and later. The HT Control field may include signaling to indicate what variant the HT Control field is. For example, some bits of the HT Control field may indicate what variant the HT Control field is. When the value of B0 is 0, B0 can indicate that the HT Control field is an HT variant. When the value of B0 is 1, B0 can indicate that the HT Control field is a VHT variant, an HE variant, or an EHT variant. When the value of B0 is 1 and the value of B1 is 0, B0 and B1 can indicate that the HT Control field is a VHT variant. When the value of B0 is 1 and the value of B1 is 1, B0 and B1 can indicate that the HT Control field is an HE variant or an EHT variant.In further specific embodiments, when the B0 value is 1 and the B1 value is 1, B0 and B1 can indicate that the HT Control field is an HE variant, an EHT variant, or a variant of the HT Control field included in a PPDU introduced after the 802.11be standard. Also, when the HT Control field is an HE variant, an EHT variant, or a variant of the HT Control field included in a PPDU introduced after the 802.11be standard, the HT Control field can include an A (aggregated control)-Control subfield. For example, HT Control fields B2 to B31 may be A-Control subfields. The A-Control subfield can include control information.

[0157] Figure 13(c) shows the A-Control subfield of Figure 13(b). The A-Control subfield may include a Control List subfield and a Padding subfield. The Control List subfield may include one or more control information. The Control List subfield may also include one or more Control subfields. Furthermore, the A-Control subfield may or may not include a Padding subfield. For example, the Padding subfield may be the remainder of the length of the pre-set A-Control subfield after excluding the Control List subfield. In a specific embodiment, the Padding subfield may be set to a pre-set value. Alternatively, the Padding subfield may start with a pre-set value.

[0158] Figure 13(d) shows the format of the Control subfield in Figure 13(c). The Control subfield may include a Control ID subfield and a Control Information subfield.

[0159] The Control ID subfield can indicate what content is contained in the Control Information subfield, or what control information is contained in the Control subfield that contains the Control ID subfield. The station can also determine the length of the Control Information subfield based on the value of the Control ID subfield. The length of the Control ID subfield may be 4 bits. The information that the Control subfield may contain may include the aforementioned TRS (triggered response scheduling) Control. The Control subfield may contain a TRS, which is information that triggers transmission by a station that receives the Control subfield. The value of the Control ID corresponding to TRS may be 0. The Control subfield may also contain information about the operating mode (OM). The value of the Control ID corresponding to OM may be 1. The Control subfield may also contain information about link adaptation. The value of the Control ID corresponding to link adaptation information may be 2. The Control subfield may also contain information about buffers. Buffer information may be a buffer status report (BSR). The value of the Control ID corresponding to BSR may be 3. The Control subfield may also contain information regarding the uplink power headroom (UL power headroom). This information may indicate how much additional power is available for transmission or may be a value used for power pre-correction. The Control ID value corresponding to the information regarding the uplink power headroom may be 4. The Control subfield may also contain signaling indicating the state of the subchannel.Signaling indicating the status of a subchannel may include a bandwidth query report (BQR). The Control ID value corresponding to the BQR may be 5. For example, the BQR can indicate whether the subchannel is available or not. The Control subfield may also include information about the command and status (CAS). The Control ID value corresponding to the CAS may be 6.

[0160] Figure 13(e) shows the format of the Control Information subfield when the Control subfield includes a CAS. According to embodiments of the present invention, the A-Control subfield can include an AC Constraint subfield and an RDG / More PPDU subfield. Specifically, when the A-Control subfield includes a CAS, the Control Information subfield corresponding to the CAS can include an AC Constraint subfield and an RDG / More PPDU subfield. For example, the first and second bits of the Control Information subfield corresponding to the CAS may be the AC Constraint subfield and the RDG / More PPDU subfield, respectively. The CAS can also include a PSRT PPDU subfield. The PSRT subfield can indicate whether the PPDU containing the PSRT subfield is a PSRT (parameterized spatial reuse transmission) PPDU. A PSRT PPDU is a PPDU transmitted by a parameterized spatial reuse (PSR) opportunity. Furthermore, when the Control subfield includes a CAS, the Control Information subfield can include a Reserved field.

[0161] The AC Constraint subfield and RDG / More PPDU subfield described in Figure 13 may be the same as the AC Constraint subfield and RDG / More PPDU subfield described in the previous drawing.

[0162] The aforementioned TID-to-link mapping may also be applied when an RD exchange takes place. In this case, AC limitations may also be applied during the RD exchange. Therefore, when an RD exchange takes place on a link to which TID-to-link mapping is applied, the range of frames that the RD responder can transmit in the RD response may become an issue. This will be explained using Figures 14 to 20.

[0163] Figure 14 shows that, according to one embodiment of the present invention, RD exchange is performed on a link to which TID-to-link mapping is applied, without AC limitations.

[0164] When an RD exchange takes place on a link to which TID-to-link mapping is applied, and AC restrictions are not applied in the RD exchange, the RD responder can send an RD response based on the TID or AC mapped to the link. Specifically, when an RD exchange takes place on a link to which TID-to-link mapping is applied, and AC restrictions are not applied in the RD exchange, the RD responder can send a frame in the RD response that corresponds to either the TID or AC mapped to the link. In this case, the RD responder may choose either the AC or TID mapped to the link, and send a data frame in the RD response that corresponds to the selected AC or TID. Specifically, the RD responder does not need to include a data frame corresponding to the TID mapped to the link in the PPDU sent as a response to a PPDU containing an RDG, but does not need to include a data frame corresponding to a TID that is not mapped to the link. In other words, even if AC restrictions are not applied, the RD responder does not need to be permitted to send a frame corresponding to the TID mapped to the link, a TID that is not AC, a TID that is AC, or an AC.

[0165] In further specific embodiments, when an RD exchange is performed on a link to which TID-to-link mapping is applied and AC restrictions are not applied in the RD exchange, the RD responder may send a data frame in the RD response that corresponds to a TID or AC with the same or higher priority than the TID or AC mapped to the link. Specifically, when an RD exchange is performed on a link to which TID-to-link mapping is applied and AC restrictions are not applied in the RD exchange, the RD responder may send a data frame in the RD response that corresponds to a TID or AC with a priority higher than the lowest priority among the TID or AC mapped to the link. Therefore, when an RD exchange is performed on a link to which TID-to-link mapping is applied and AC restrictions are not applied in the RD exchange, the RD responder may not be able to send a data frame in the RD response that corresponds to the lowest priority TID or AC among the TID or AC mapped to the link.

[0166] In the embodiment described above, the TID-to-link mapping can refer to the TID-to-link mapping applied when the RD responder transmits. This is because the TID-to-link mapping applied to the RD initiator does not apply to the RD responder. Furthermore, such an embodiment may also be applied when the RD responder transmits to multiple stations in the RD response.

[0167] In the embodiment shown in Figure 14, 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 first AP (AP1) and the first station (STA1) are connected by a first link (Link1), and the second AP (AP2) and the second station (STA2) are connected by a second link (Link1). All TIDs are mapped to the first link (Link1). The second AP (AP2) can transmit all TIDs on the second link (Link2). However, when the second station (STA2) transmits a data frame on the second link (Link2), TID-to-link mapping allows the second station (STA2) to transmit data frames corresponding to AC_VO and AC_VI on the second link (Link2).

[0168] On the second link (Link2), the second AP (AP2) sends an RDG to the second station. At this time, the second AP (AP2) signals that the AC constraint is not applied by setting the value of the AC Constraint subfield to 0. The second station (STA2) sends a data frame corresponding to AC_VI or AC_VO in its RD response. Furthermore, the second station (STA2) cannot send a data frame that does not correspond to AC_VI or AC_VO in its RD response.

[0169] Figure 15 shows that RD exchanges without AC limitations are performed on a link to which TID-to-link mapping is applied according to yet another embodiment of the present invention.

[0170] When an RD exchange takes place on a link to which TID-to-link mapping is applied, and AC restrictions are not applied in the RD exchange, the RD responder can send an RD response regardless of TID-to-link mapping. Specifically, when an RD exchange takes place on a link to which TID-to-link mapping is applied, and AC restrictions are not applied in the RD exchange, the RD responder can send a data frame in the RD response that corresponds to any TID, regardless of TID-to-link mapping. In a specific example, when an RD exchange takes place on a link to which TID-to-link mapping is applied, and AC restrictions are not applied in the RD exchange, the RD responder can send a data frame in the RD response that corresponds to an AC or TID that is not mapped to the link.

[0171] In the embodiment described above, the TID-to-link mapping can represent the TID-to-link mapping applied when the RD responder transmits. This is because the TID-to-link mapping applied to the RD initiator is not applied to the RD responder. Furthermore, such an embodiment may also be applied when the RD responder transmits to multiple stations in the RD response.

[0172] 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 first AP (AP1) and the first station (STA1) are connected by a first link (Link1), and the second AP (AP2) and the second station (STA2) are connected by a second link (Link1). All TIDs are mapped to the first link (Link1). The second AP (AP2) can transmit all TIDs on the second link (Link2), but due to the TID-to-link mapping applied to the second link (Link2), when the second station (STA2) transmits a data frame on the second link (Link2), the second station (STA2) can transmit data frames corresponding to AC_VO and AC_VI on the second link (Link2).

[0173] On the second link (Link2), the second access point (AP2) sends an RDG to the second station. At this time, the second AP (AP2) signals that the AC constraint is not applied by setting the value of the AC Constraint subfield to 0. The second station (STA2) can send a data frame corresponding to any TID regardless of the TID-to-link mapping applied to the second link (Link2) in its RD response. Therefore, the second station (STA2) sends a QoS data frame corresponding to AC_BE, which is an AC that is not mapped to the second link (Link2), in its RD response.

[0174] Figure 16 shows that no AC limit is set when RD exchange is performed on a link to which TID-to-link mapping is applied according to yet another embodiment of the present invention.

[0175] If the TID or AC of a frame transmitted by an RD initiator using a PPDU containing an RDG is not mapped to the link used by the RD responder for their RD response, the RD initiator may not be permitted to apply the AC restriction. In other words, if the TID or AC of a frame transmitted by an RD initiator using a PPDU containing an RDG is not mapped to the link used by the RD responder for their RD response, the RD initiator may not apply the AC restriction. In this case, the RD initiator may signal that the AC restriction is not applied.

[0176] In another specific embodiment, if a TID or AC with a higher priority than the TID or AC of a frame transmitted by the RD initiator using a PPDU containing an RDG is not mapped to the link used by the RD responder for the RD response, the RD initiator may not be permitted to apply the AC restriction. That is, if a TID or AC with a higher priority than the TID or AC of a frame transmitted by the RD initiator using a PPDU containing an RDG is not mapped to the link used by the RD responder for the RD response, the RD initiator may not be permitted to apply the AC restriction. In this case, the RD initiator may signal that the AC restriction is not applied.

[0177] In the embodiments described above, the TID or AC of a frame transmitted by the RD initiator using a PPDU containing an RDG may be the lowest priority TID or AC among the TIDs or ACs of frames transmitted by the RD initiator using a PPDU containing an RDG. In yet another specific embodiment, the TID or AC of a frame transmitted by the RD initiator using a PPDU containing an RDG may be the lowest priority TID or AC among the TIDs or ACs of frames received by the RD responder from the PPDU containing an RDG. In yet another specific embodiment, the TID or AC of a frame transmitted by the RD initiator using a PPDU containing an RDG may be the TID or AC of the last frame received by the RD initiator using a PPDU containing an RDG. In yet another specific embodiment, the TID or AC of a frame transmitted by the RD initiator using a PPDU containing an RDG may be the TID or AC of the last frame received by the RD responder from the PPDU containing an RDG.

[0178] In the embodiment described above, the TID-to-link mapping can represent the TID-to-link mapping applied when the RD responder transmits. This is because the TID-to-link mapping applied to the RD initiator is not applied to the RD responder. Furthermore, such an embodiment may also be applied when the RD responder transmits to multiple stations in the RD response.

[0179] In the embodiment shown in Figure 16, 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 first AP (AP1) and the first station (STA1) are connected by a first link (Link1), and the second AP (AP2) and the second station (STA2) are connected by a second link (Link1). All TIDs are mapped to the first link (Link1). The second AP (AP2) can transmit all TIDs on the second link (Link2). However, when the second station (STA2) transmits a data frame on the second link (Link2), TID-to-link mapping allows the second station (STA2) to transmit frames corresponding to AC_VO and AC_VI on the second link (Link2).

[0180] On the second link (Link2), the second AP (AP2) transmits an RDG to the second station. At this time, the second AP (AP2) signals that the AC constraint is not applied by setting the value of the AC Constraint subfield to 0. This is because the second AP (AP2) transmits a QoS data frame corresponding to AC_BE using a PPDU containing the RDG, and AC_BE is not mapped to the TID transmitted by the second station (STA2) on the second link (Link2). The second station (STA2) can then respond with an RD using either of the embodiments described earlier in Figures 14 and 15.

[0181] Figure 17 shows that RD exchange occurs when AC limiting is applied to a link to which TID-to-link mapping is applied according to yet another embodiment of the present invention.

[0182] If the RD initiator signals in the RD response that the AC is restricted, the RD responder may be permitted in the RD response to send a frame that corresponds to a TID or AC not mapped to the link on which the RD response is being made. In this case, the RD responder may determine the TID or AC of the frame they send in the RD response based on the TID or AC of the frame received from the PPDU containing the RDG. Specifically, the RD responder may determine the TID or AC of the frame they send in the RD response to be the same as the TID or AC of the frame received from the PPDU containing the RDG. In yet another specific embodiment, the RD responder may determine the TID or AC of the frame they send in the RD response to be the same as, or have a higher priority than, the TID or AC of the frame received from the PPDU containing the RDG. The TID or AC of the frame received from the PPDU containing the RDG may be the TID or AC of the last frame received from the PPDU containing the RDG. Furthermore, as in the embodiment described above, exceptional transmission of TID-to-link mapping may be permitted only in RD exchanges where AC restriction has been signaled.

[0183] In the embodiment described above, the TID-to-link mapping can represent the TID-to-link mapping applied when the RD responder transmits. This is because the TID-to-link mapping applied to the RD initiator is not applied to the RD responder. Furthermore, such an embodiment may also be applied when the RD responder transmits to multiple stations in the RD response.

[0184] In the embodiment shown in Figure 17, 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 first AP (AP1) and the first station (STA1) are connected by a first link (Link1), and the second AP (AP2) and the second station (STA2) are connected by a second link (Link1). All TIDs are mapped to the first link (Link1). The second AP (AP2) can transmit all TIDs on the second link (Link2), but due to the TID-to-link mapping applied to the second link (Link2), the second station (STA2) can transmit only frames corresponding to AC_VO and AC_VI on the second link (Link2).

[0185] On the second link (Link2), the second access point (AP2) sends an RDG to the second station. At this time, the second AP (AP2) signals that the AC restriction is applied by setting the value of the AC Constraint subfield to 1. The second AP (AP2) also sends a QoS data frame corresponding to AC_BE using a PPDU that includes the RDG. The second station (STA2) does not have AC_BE mapped to the second link (Link2), but sends a frame corresponding to AC_BE in its RD response.

[0186] Figure 18 shows that, according to yet another embodiment of the present invention, RD exchange occurs when AC limiting is applied on a link to which TID-to-link mapping is applied.

[0187] In another embodiment, if the RD initiator signals that AC will be restricted in the RD response, and TID-to-link mapping is applied to the link on which the RD response is made, the RD responder can transmit any TID in the RD response. That is, if the RD initiator signals that AC will be restricted in the RD response, and TID-to-link mapping is applied to the link on which the RD response is made, the RD responder can transmit the RD response as described in the embodiment shown in Figure 15.

[0188] In the embodiment shown in Figure 18, 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 first AP (AP1) and the first station (STA1) are connected by a first link (Link1), and the second AP (AP2) and the second station (STA2) are connected by a second link (Link1). All TIDs are mapped to the first link (Link1). The second AP (AP2) can transmit all TIDs on the second link (Link2). However, when the second station (STA2) transmits a data frame on the second link (Link2), TID-to-link mapping allows the second station (STA2) to transmit data frames corresponding to AC_VO and AC_VI on the second link (Link2).

[0189] On the second link (Link2), the second AP (AP2) sends an RDG to the second station. At this time, the second AP (AP2) signals that the AC restriction is applied by setting the value of the AC Constraint subfield to 1. In the RD response, the second station (STA2) may send a data frame corresponding to any TID, including TIDs that do not correspond to the AC or TID mapped to the second link.

[0190] When an RD exchange takes place on a link to which TID-to-link mapping is applied, and AC restrictions are applied in the RD exchange, the RD responder can send an RD response based on the TID or AC mapped to the link. Specifically, when an RD exchange takes place on a link to which TID-to-link mapping is applied, and AC restrictions are applied in the RD exchange, the RD responder can send a data frame that corresponds to an AC or TID with the same or higher priority as the AC or TID of the frame received from the RD initiator, and that corresponds to one of the TIDs or ACs mapped to the link in the RD response. For convenience of explanation, a PPDU sent as a response to a PPDU containing an RDG is called an RD response PPDU. Specifically, when an RD responder sends a data frame in an RD response, the RD responder does not need to include in the RD response PPDU any data frames that correspond to a TID or AC with a lower priority than the TID or AC of the frame received from the RD initiator, or to a TID or AC that is not mapped to the link. At this time, the RD responder may include in the PPDU sent as a response to the PPDU containing the RDG (RD response PPDU) a data frame that corresponds to a TID or AC that is the same as or has a higher priority than the TID or AC of the frame received from the RD responder, and that corresponds to a TID or AC mapped to the link.

[0191] A frame received from an RD initiator may represent the last frame received by the RD responder from the RD initiator. In another specific embodiment, if the RD responder receives multiple frames from the RD initiator, the frame received from the RD initiator may represent the TID or AC of the frame received from the RD initiator that has the lowest priority. In this case, the multiple frames may be multiple frames included in the last PPDU received by the RD responder from the RD initiator.

[0192] Figure 19 shows an embodiment of the present invention that signals information regarding AC limits used in the RD initiator RD response.

[0193] The RD initiator can signal information about AC constraints applied in the RD exchange. For convenience of explanation, such signaling is referred to as AC constraint information signaling. Based on the AC constraint information signaling, the RD responder can determine whether the frame to send in the RD response is AC or TID. The information about AC constraints applied in the RD exchange may be the information used in the embodiments described in Figures 11 to 18. For example, the AC constraint information can indicate the AC constraint method in the embodiments described in Figures 11 to 18. For example, the AC constraint information signaling can indicate whether TID-to-link mapping should be applied in the RD response. If the AC constraint information signaling is a pre-specified first value and the AC Constraint subfield indicates that TID or AC is not restricted, the RD responder can send the RD response regardless of TID-to-link mapping. If the AC constraint information signaling is a pre-specified second value and the AC Constraint subfield indicates that TID or AC is not restricted, the RD responder can send the RD response by TID-to-link mapping. Specifically, if the AC restriction information signaling is a pre-specified second value and the AC Constraint subfield indicates that the TID or AC is not restricted, the RD responder can use only the TID or AC mapped to the link where the RD response is made via TID-to-link mapping to make the RD response.

[0194] If the AC Constraint subfield indicates that the TID or AC is restricted, the RD responder can decide whether or not to apply the TID-to-link mapping to make an RD response based on the AC restriction information signaling.

[0195] AC restriction information signaling may be included in the A-Control subfield. In other specific embodiments, AC restriction information signaling may be included in the CAS. Figure 19 shows the Control Information subfield of a CAS according to one embodiment of the present invention. In this case, the Control Information subfield includes AC restriction information signaling (AC Indication subfield). In yet another specific embodiment, AC restriction information signaling may be included in the Reserved field of the Control Information subfield described in Figure 13(e).

[0196] Figure 20 shows that, according to an embodiment of the present invention, RD exchange occurs when a PPDU with synchronized transmission termination is transmitted across multiple links.

[0197] A single multilink device can synchronize PPDUs transmitted across multiple links. Specifically, a single multilink device can synchronize the ends of PPDUs transmitted across multiple links. In further specific embodiments, a single multilink device can synchronize the beginnings of PPDUs transmitted across multiple links. Such operation may be applied when there are limitations on the transmit / receive capabilities of a multilink device that receives PPDUs on at least one of the multiple links. Such operation may be applied when a multilink device that receives PPDUs on at least one of the multiple links cannot simultaneously receive and transmit on either link. When a multilink device can receive on one link while transmitting on another, it is called an STR (simultaneous transmit and receive; simultaneous transmission and reception) multilink device. When a multilink device cannot receive on one link while transmitting on another, it is called a non-STR multilink device. Therefore, a multilink device that transmits to a non-STR multilink device on multiple links can transmit synchronized PPDUs.

[0198] RD exchange may be configured depending on whether or not a synchronized PPDU is sent.

[0199] When a PPDU synchronized across multiple links is transmitted, the multilink device may transmit an RDG on only one of the multiple links. In this case, an RD response may be transmitted only on the link on which the RDG was transmitted. For example, when a multilink device transmits a PPDU synchronized across two links, the multilink device may include an RDG in the PPDU transmitted on the first link. In this case, the PPDU transmitted in response to the PPDU synchronized on the first link is the first PPDU, and the PPDU transmitted in response to the PPDU synchronized on the second link is the second PPDU. The first PPDU contains a first frame, and the second PPDU contains a second frame, with the length of the first frame being longer than the length of the second frame. For example, the first frame may contain a data frame, and the second frame may contain an ACK. In this case, the second PPDU may need to include padding to synchronize the first and second PPDUs. This may increase the inefficiency of transmission.

[0200] When a synchronized PPDU is transmitted across multiple links, the RDG may or may not be transmitted across all links. When a multilink device transmits a synchronized PPDU across multiple links, the multilink device may set the value of the RDG / More PPDU subfield transmitted across all links to be the same. When a multilink device transmits a synchronized PPDU across multiple links, the multilink device may set the value of the RDG / More PPDU subfield transmitted across all links to 1 or to 0. This can improve transmission efficiency.

[0201] In other specific embodiments, RDGs may be sent on all of the links, or none of them may be sent, regardless of whether or not a synchronized PPDU is sent.

[0202] In further specific embodiments, if a multilink device receiving PPDUs on multiple links is a non-STR multilink device, then RDGs may be transmitted on all of the links, or none of the links may be transmitted. If a multilink device receiving PPDUs on multiple links is a non-STR multilink device, the multilink device may set the value of the RDG / More PPDU subfield transmitted on all of the links to be the same. If a multilink device receiving PPDUs on multiple links is a non-STR multilink device, the multilink device may set the value of the RDG / More PPDU subfield transmitted on all of the links to 1, or to 0. This is because if RD exchange is performed with a non-STR multilink device on only one link, transmission on the other links may be restricted.

[0203] In the embodiment shown in Figure 20, the AP multilink device includes a first AP (AP1) and a second AP (AP2). The No-AP multilink device includes a first station (STA1) and a second station (STA2). The first AP (AP1) and the first station (STA1) are connected by a first link (Link1), and the second AP (AP2) and the second station (STA2) are connected by a second link (Link2). At this time, the first AP (AP1) and the second AP (AP2) transmit synchronized PPDUs and set the value of the RDG / More PPDU subfield to be the same. Specifically, the first AP (AP1) and the second AP (AP2) set the value of the RDG / More PPDU subfield to 1 and transmit synchronized PPDUs. Also, the first station (STA1) and the second station (STA2) set the value of the RDG / More PPDU subfield to 1 and transmit synchronized PPDUs. Station 1 (STA1) and Station 2 (STA2) set the value of the RDG / More PPDU subfield to 0 and send the synchronized additional PPDU.

[0204] Furthermore, when a multilink device initiates RD exchange on multiple links and error recovery is performed on multiple links, error recovery may be performed simultaneously on multiple links. That is, error recovery may be performed on all of the links, or not on all of the links. Such embodiments may be applied when the RD initiator is a non-STR multilink device or the RD responder is a non-STR device. This is because it is difficult to transmit a synchronized PPDU on multiple links if error recovery is performed on only one of the links.

[0205] When the RD initiator is a multilink device and the RD responder is also a multilink device, and the RD exchange signaling is transmitted on one of the links, the RD exchange signaling may also be applied to the remaining links of the multiple links in addition to that link. In this case, the RD exchange signaling may include at least one of the aforementioned RDG, information regarding additional PPDUs, and AC limit signaling information. In this case, the information regarding the RDG and additional PPDUs may be transmitted by the aforementioned RDG / More PPDU subfield. For example, an RD initiator and an RD responder, both multilink devices, may be coupled on the first and second links. In this case, when an RDG is transmitted on the first link, it may be considered that an RDG has been transmitted from the second link. Also, when it is signaled that an additional PPDU is being transmitted on the first link, it may be considered that an additional PPDU is also being transmitted on the second link. Such embodiments may be applied when synchronized PPDUs are being transmitted. Furthermore, if frame reception is successful on one link but fails on another, the signaling for RD exchange may be applied not only to the link in question but also to the remaining links of the multiple links. This ensures that RD exchange can be performed stably on multiple links even if transmission fails on one link.

[0206] The IEEE 802.11be standard supports a bandwidth of 320 MHz, which is twice as wide as the 160 MHz maximum bandwidth supported by the previous 802.11 standard. Furthermore, in standards prior to IEEE 802.11be, preamble puncturing was only permitted to a limited extent in DL (downlink) MU PPDU, and the resource units (RUs) assigned to each station were limited to one consecutive RU (996 x 2 tone size). In IEEE 802.11be, preamble puncturing is permitted even in UL (uplink) transmission, and each station may be assigned two or more non-contiguous RUs. In this case, some RU combinations may not be permitted due to their difficulty of implementation and efficiency.

[0207] Figure 21 shows the RU configuration that can be assigned to one station using IEEE 802.11ax and the RU configuration that can be assigned to one station using an embodiment of the present invention.

[0208] Furthermore, the IEEE 802.11be standard also supports small RUs, which are RUs smaller than 20MHz 242 tone sizes. Specifically, the IEEE 802.11be standard allows stations to be assigned 26+52 tone size RUs, 26+52 tone size RUs, and 26+52 tone size RUs. Figure 21 omits the small RUs.

[0209] Figure 21(a) shows 996-tone-size RUs in an 80MHz channel and 996×2-tone-size RUs in a 160MHz channel according to the IEEE 802.11ax standard. In IEEE 802.11ax, when an AP uses a trigger frame to trigger a station to perform a UL transmission using a bandwidth greater than 40MHz, it can only allocate a station to a continuous 80MHz RU or a continuous 160MHz RU. In this case, when the AP triggers a station to perform a UL OFDMA transmission and allocates a bandwidth greater than 40MHz to the station, the AP can only allocate an 80MHz RU to the station. Also, in IEEE 802.11ax, when an AP uses a RU greater than 40MHz while performing DL OFDMA, only an 80MHz RU is permitted.

[0210] Figure 21(b) shows four types of 60MHz (242+484 tone size) RUs permitted within the 80MHz channel and four types of 120MHz (484+996 tone size) RUs permitted within the 160MHz channel in the IEEE 802.11be standard. In the IEEE 802.11be standard, when an AP assigns a station an RU greater than 40MHz using a trigger frame, the AP can assign the station four forms of 60MHz RUs in addition to 80MHz RUs. The AP can also assign the station four forms of 120MHz RUs or four forms of 160MHz RUs. Furthermore, these various forms of RUs may be used not only in UL transmission but also in DL PPDU using OFDMA. The effects obtained when these various forms of RUs are used will be explained with reference to Figure 22.

[0211] Figure 22 shows the IEEE 802.11ax standard and the OFDMA DL PPDU used in the embodiment of the present invention.

[0212] Figure 22 shows that the AP transmits OFDMA DL PPDUs to the first station (STA1) and the second station (STA2). In this case, the OFDMA DL PPDU consists of a first PPDU (PPDU1) and a second PPDU (PPDU2). The figure illustrates a case where the frequency bandwidth allocated to the first PPDU (PPDU1) and the second PPDU (PPDU2) differs due to differences in the MCS (modulation & coding scheme) used when encoding them. Thus, when the available frequency bandwidths for multiple PPDUs transmitted together differ, it is efficient to use minimal padding for each PPDU. However, if the selectable RUs are limited, it may be necessary to either abandon transmission to one of the stations or require excessive padding.

[0213] Figure 22(a) shows that the AP transmits an OFDMA DL PPDU using only the RU allocations permitted by the IEEE 802.11ax standard. The AP transmits the first PPDU (PPDU1) and the second PPDU (PPDU2) to both the first station (STA1) and the second station (STA2) using an 80MHz RU. Therefore, a large amount of padding is used when transmitting the first PPDU (PPDU1).

[0214] Figure 22(b) shows that the AP transmits an OFDMA DL PPDU using only RU allocations permitted by the IEEE 802.11ax standard. Since RUs with various bandwidths can be allocated, less padding is used in Figure 22(b) compared to Figure 22(a). In addition to the OFDMA DL PPDU described in Figure 22, transmission efficiency can also be improved in TB PPDU when RUs with various bandwidths are used.

[0215] The existing 802.11 standard performs a backoff procedure based on the CCA of the 20MHz primary channel (in this specification, the 20MHz primary channel refers to a primary channel with a bandwidth of 20MHz). Specifically, even when accessing channels exceeding 20MHz, access to channels other than the 20MHz primary channel is only possible if the CCA result of the 20MHz primary channel is idle. As the maximum bandwidth available to the station increases, the inefficiency of this channel access method can become greater. Therefore, a method is needed that allows channel access on channels other than the 20MHz primary channel even when the 20MHz primary channel is busy.

[0216] In a specific embodiment, a station can perform the backoff procedure using a subchannel instead of the 20MHz main channel. In this case, the station can perform the backoff procedure using the subchannel instead of the 20MHz main channel only if the 20MHz main channel is detected as busy. Specifically, if the 20MHz main channel is detected as busy and the target station of the PPDU transmitted on the 20MHz main channel is not the station, the station can perform the backoff procedure using the subchannel instead of the 20MHz main channel. Therefore, the station can perform the backoff procedure using the subchannel instead of the 20MHz main channel only if it decodes the preamble of the PPDU received on the 20MHz main channel. Furthermore, the station can decode the preamble of the PPDU to determine the STA-ID of the EHT-SIG. In yet another specific embodiment, the station can decode the first MAC frame of the PPDU to determine the intended recipient of the MAC frame. Furthermore, if a station confirms that a PPDU received on the 20MHz main channel was transmitted from a BSS other than the one to which the station belongs, that is, if it is determined to be an Inter-BSS PPDU, the station may perform the backoff procedure using a subchannel instead of the 20MHz main channel. To this end, the station can decode the PPDU's preamble to determine the BSS color, either HE-SIG or U-SIG. If the station determines that a PPDU transmitted on the 20MHz main channel is an Inter-BSS PPDU, the station may omit the procedure described above to determine whether the intended recipient of the PPDU is the station itself.

[0217] Furthermore, if the subchannel on which channel access is performed is idle in DIFS, the station can initiate the backoff procedure using the subchannel instead of the 20MHz main channel.

[0218] Embodiments may be applied to compensate for the time required to decode the preamble of a PPDU transmitted on the 20MHz main channel. Using a subchannel instead of the 20MHz main channel, the backoff procedure can be initiated by decrementing the backoff counter by a predetermined number. In this case, the predetermined number may be determined based on the time required to decode the PPDU preamble. For example, if the time required to decode the PPDU preamble is 3 slots (e.g., 27us), the predetermined number may be 3. In further specific embodiments, the backoff procedure may be performed without such compensation. The backoff procedure method using a subchannel instead of the 20MHz main channel will be explained with reference to Figures 23 to 27.

[0219] Figure 23 shows that, according to an embodiment of the present invention, the backoff procedure is performed using a subchannel instead of a 20MHz main channel.

[0220] In the backoff procedure, the station performs a CCA on a slot-by-slot basis. If the CCA reveals that a channel is idle, the station decrements the backoff counter value by 1. If the CCA reveals that a channel is not idle, the station maintains the backoff counter value. As mentioned above, a slot-by-slot CCA may also be performed when the backoff procedure is carried out on a subchannel rather than the 20MHz main channel. Furthermore, the bandwidth of subchannels other than the 20MHz main channel may also be 20MHz.

[0221] There may be two or more channels other than the 20MHz main channel on which the station performs backoff procedures. For example, if the station operates on an 80MHz channel, the station can access channels based on backoff procedures on three 20MHz subchannels. The number of subchannels other than the 20MHz main channel on which the station can perform backoff procedures may be determined by the station's capability. Furthermore, in other specific embodiments, the number of subchannels other than the 20MHz main channel on which the station can perform backoff procedures may be a predetermined number. In this case, the predetermined number may be 1 or 2.

[0222] The station can set and manage separate backoff counters for the 20MHz main channel and for subchannels other than the 20MHz main channel. Specifically, the station can change the backoff counter for each channel based on the channel access results for each channel. That is, if the station successfully transmits on a channel, the station can acquire a new backoff counter for that channel within CW_min for that channel's backoff counter. If the station fails to transmit on a channel, the station can either double the CW value for that channel's backoff counter or acquire a new backoff counter for that channel within CWmax. Figure 23(b) shows how the backoff counter values ​​are set and managed separately for each subchannel. In Figure 23(b), the station sets the initial value of the backoff counter to 4 for the 20MHz main channel (P20) and sets the initial value of the backoff counter to 5 for the first subchannel (S20_1). After the station transmits the PPDU on the first subchannel (S20_1), second subchannel (S20_2), and third subchannel (S20_3), the station performs channel access again on the 20MHz main channel. At this time, the station continues to use the backoff counter for the 20MHz main channel.

[0223] The station can set and manage a single backoff counter that is used in common for the 20MHz main channel and the subchannels other than the 20MHz main channel. Figure 23(a) shows that the station uses a single common backoff counter for the 20MHz main channel and the subchannels other than the 20MHz main channel in this way. In Figure 23(a), the station sets the initial value of the backoff counter to 5 for the 20MHz main channel (P20). Since the 20MHz main channel (P20) is idle in 3 slots on the main channel, the station decreases the backoff counter by 3. Subsequently, since the 20MHz main channel (P20) is not idle and the first subchannel (S20_1) is idle due to DIFS, the station starts the backoff procedure on the first subchannel (S20_1). At this time, the first subchannel (S20_1) is idle with 3 slots, and the second subchannel (S20_2) and third subchannel (S20_3) are idle with PIFS, so the station transmits PPDU on the first subchannel (S20_1), second subchannel (S20_2), and third subchannel (S20_3). After that, the station acquires a new backoff counter and performs channel access. Unlike the embodiment in Figure 20(a), if the first subchannel (S20_1) is also detected as not idle, and the station can perform the backoff procedure on the second subchannel (S20_2), the station can perform the backoff procedure on the second subchannel (S20_2). At this time, if the station cannot perform the backoff procedure on the second subchannel (S20_2), the station may wait until the 20MHz main channel (P20) or the first subchannel (S20_1) becomes idle.

[0224] When a station successfully accesses a channel on a subchannel other than the 20MHz main channel and transmits a PPDU, the length of the PPDU may be limited. First, while the station accesses and transmits via a subchannel instead of the 20MHz main channel, the AP coupled to the station cannot transmit or receive on the 20MHz main channel either. Therefore, scanning and other operations performed via the 20MHz main channel do not need to be performed. Also, it is not possible to receive Inter-BSS PPDUs transmitted via the 20MHz main channel, and NAV cannot be configured based on Inter-BSS PPDUs. Therefore, when a station successfully accesses a channel on a subchannel instead of the 20MHz main channel and transmits a PPDU, the length of the PPDU needs to be limited. Furthermore, for fairness with stations that adhere to existing standards, it is necessary to limit the length of the PPDU when a station successfully accesses a channel on a subchannel instead of the 20MHz main channel and transmits a PPDU. In addition, as mentioned above, the number of subchannels on which a station can perform backoff procedures may be limited. These embodiments will be explained in detail using Figure 24.

[0225] Figure 24 shows that, according to an embodiment of the present invention, the length of the PPDU is limited when the station successfully accesses the channel on a subchannel instead of the 20MHz main channel and transmits the PPDU.

[0226] When a station successfully accesses a channel on a subchannel instead of the 20MHz main channel and transmits a PPDU, the station can terminate the transmission of the PPDU within a timeframe determined based on the transmission of the Inter-BSS PPDU on the 20MHz main channel. In this case, the timeframe determined based on the transmission of the Inter-BSS PPDU may be the termination time of the Inter-BSS PPDU. In other specific embodiments, the timeframe determined based on the transmission of the Inter-BSS PPDU may be the time when the ACK for the transmission of the Inter-BSS PPDU is completed. The station can determine the timeframe determined based on the transmission of the Inter-BSS PPDU based on the value of the length field of the L-SIG of the Inter-BSS PPDU. Alternatively, the station can determine the timeframe determined based on the transmission of the Inter-BSS PPDU based on the value of the TXOP field of the signaling field of the Inter-BSS PPDU.

[0227] In the embodiment shown in Figure 24, the station transmits the PPDU via the first subchannel (S20_1), the second subchannel (S20_2), and the third subchannel (S20_3) within the length of the Inter-BSS PPDU (OBSS PPDU) transmitted on the 20MHz main channel (P20).

[0228] If a station allows channel access on subchannels other than the 20MHz main channel, the AP must perform PPDU detection on subchannels in addition to the 20MHz main channel in order to receive the PPDU. Specifically, when an Inter-BSS PPDU is transmitted on the 20MHz main channel, the AP can perform PPDU detection on subchannels in addition to the 20MHz main channel. PPDU detection may involve searching for the PPDU preamble. In such an embodiment, the AP can search for the PPDU on subchannels where no Inter-BSS PPDU is transmitted. In this case, the order of subchannels on which the AP searches for the PPDU may be predetermined. For example, when an Inter-BSS PPDU with a 40MHz bandwidth is transmitted on the 20MHz main channel, the AP can search for the PPDU on subchannels 40MHz away from the 20MHz main channel.

[0229] Thus, additional processing is required at the station to receive PPDUs transmitted on channels that do not include the 20MHz main channel. Therefore, the station does not need to support the reception of PPDUs transmitted on channels that do not include the 20MHz main channel. The station can signal whether or not it will support the reception of PPDUs transmitted on channels that do not include the 20MHz main channel. Specifically, the station can signal to the AP using the Capability element whether or not it will support the reception of PPDUs transmitted on channels that do not include the 20MHz main channel. When the AP sets up a PPDU on a channel that does not include the 20MHz main channel, the AP can include in the PPDU only frames that are received by stations that have signaled that they will support the reception of PPDUs transmitted on channels that do not include the 20MHz main channel.

[0230] The IEEE 802.11be standard allows segments to be divided into 80MHz units, which can be called 80MHz segments. It also specifies that different signaling fields, such as EHT-SIG or U-SIG, may be transmitted within a single PPDU for each 80MHz segment. Figure 25 illustrates how a station performs channel access in a segment that does not include the 20MHz primary channel.

[0231] Figure 25 shows an embodiment of the present invention in which, when the 20MHz main channel is not idle, the station accesses the channel on a subchannel of a segment that is not the main segment.

[0232] As mentioned above, a station can access channels in segments that do not contain the 20MHz main channel. Specifically, if the 20MHz main channel is not idle, a station can access channels in segments that do not contain the 20MHz main channel.

[0233] In another specific embodiment, the station may be configured by the AP to receive and decode the preamble via a subchannel other than the 20MHz main channel. In this case, the station can access the channel on a segment that does not include the 20MHz main channel. In such an embodiment, the station does not need to know if the PPDU is being transmitted on the 20MHz main channel and can access the channel on a segment that does not include the 20MHz main channel. Transmission using a segment that does not include the 20MHz main channel in this way can be called SST (subchannel selective transmission). Furthermore, a station that receives the PPDU preamble and PPDU on a segment that does not include the 20MHz main channel can be called a parked station.

[0234] For each segment, one subchannel may be designated for channel access. If the 20MHz main channel is not idle, the station can perform channel access on the subchannel designated for channel access in segments that do not include the 20MHz main channel.

[0235] In the embodiment shown in Figure 25, the AP detects an Inter-BSS PPDU with a 40MHz bandwidth transmitted on the 20MHz main channel (P20). The AP performs a backoff procedure on the first subchannel (S20_1) of the second segment (Segment2). At this time, the first subchannel (S20_1) may be the channel designated as the channel on which the backoff procedure is performed when the backoff procedure is performed on the second segment (Segment2). A station parked on the second segment (Segment2) detects the PPDU preamble on the first subchannel (S20_1). At this time, a station parked on the second segment (Segment2) can wait for reception of the PPDU on the first subchannel (S20_1) regardless of whether the channel on which the AP performed the backoff procedure is the 20MHz main channel (P20) or the first subchannel (S20_1). Furthermore, if a station parked in Segment 2 detects a preamble for HE MU PPDU or EHT MU PPDU in the first subchannel (S20_1), the station parked in Segment 2 can decode the PPDU preamble in a subchannel other than the first subchannel (S20_1) of Segment 2 in order to determine the special stream and RU of the PPDU to be transmitted to the station.

[0236] The AP can send PPDUs not only in Segment 2, but also via subchannels that were idle during the PIFS prior to the completion of the backoff procedure in Segment 2. In this case, the AP can decide whether or not to send PPDUs in each segment depending on whether the channels designated for backoff procedures in each segment during the PIFS prior to the completion of the backoff procedure are idle. Specifically, if the channels designated for backoff procedures in each segment during the PIFS prior to the completion of the backoff procedure are idle, the AP can send PPDUs in that segment. If the channels designated for backoff procedures in each segment during the PIFS prior to the completion of the backoff procedure are not idle, the AP does not need to send PPDUs in that segment.

[0237] In the embodiment shown in Figure 25, during the PIFS before the completion of the backoff procedure in the second segment (Segment 2), it is detected that the second subchannel (S20_2), which is the subchannel where the backoff procedure is performed in the third segment (Segment 3), is not idle. Also, during the PIFS before the completion of the backoff procedure in the second segment (Segment 2), it is detected that the third subchannel (S20_3), which is the subchannel where the backoff procedure is performed in the fourth segment (Segment 4), is idle. Therefore, the AP transmits PPDUs in the second segment (Segment 2) and the fourth segment (Segment 4).

[0238] Thus, constraints may be applied to the length of the transmitted PPDU, the intended recipients of the MAC frames contained in the PPDU, and the RUs assigned to the station that receives the PPDU.

[0239] In the previously described embodiment, AP transmission was used as an example, but the above embodiment may also be applied to non-AP stations. This will be explained in detail in Figure 26.

[0240] Figure 26 shows that, according to an embodiment of the present invention, the first AP of a multilink device signals via the second AP that the first AP can receive on a subchannel other than the 20 MHz main channel.

[0241] When the first access point (AP) of a multilink device detects that its 20MHz main channel is not idle, the first AP can signal to perform a backoff procedure on a subchannel other than the 20MHz main channel via the second AP, another AP in the multilink device. At this time, the first AP can specify the subchannel on which to perform the backoff procedure via the second AP. In yet another specific embodiment, the first AP does not need to signal the subchannel on which to perform the backoff procedure via the second AP. In this case, the station can perform the backoff procedure on a pre-specified subchannel.

[0242] Furthermore, the first AP can signal, via the second AP, the time during which the first AP waits for reception on a subchannel other than the 20MHz main channel. The station can determine the length of the UL PPDU based on the signaled waiting time. Specifically, the station can determine the length of the UL PPDU so that the transmission of the UL PPDU does not persist beyond the signaled waiting time. In yet another specific embodiment, the station can determine the length of the UL PPDU so that a response to the UL PPDU, such as an ACK, is completed beyond the signaled waiting time.

[0243] In such an embodiment, the second AP can transmit a control frame containing information regarding reception standby, such as information regarding subchannels other than the 20MHz main channel of the first AP, and information regarding the standby time. In this case, the receiver address of the control frame may be the MAC address of a specific station. In this case, only the station corresponding to the receiver address can perform the backoff procedure on a subchannel instead of the 20MHz main channel. In yet another specific embodiment, the receiver address may be a group address. In this case, only the station corresponding to the group address can perform the backoff procedure on a subchannel instead of the 20MHz main channel. In this case, multiple stations can compete for channel access. In yet another specific embodiment, the receiver address may be a broadcast address. Stations that do not correspond to the receiver address can maintain a power-saving state with power-saving operation during the reception standby time.

[0244] In the embodiments described above, only one control frame containing information about waiting to receive may be transmitted, or multiple control frames may be transmitted. The control frame containing information about waiting to receive may be transmitted alone. In yet another specific embodiment, the control frame containing information about waiting to receive may be transmitted together with a data frame, another control frame, or a management frame.

[0245] Furthermore, the second AP can signal regarding TIDs that can be transmitted based on the backoff procedure of subchannels other than the 20MHz main channel. Specifically, the control frame described above may include information about TIDs available for uplink transmissions transmitted based on the backoff procedure of subchannels other than the 20MHz main channel. In this case, the TID information may be indicated by an 8-bit field. Specifically, each bit of the 8-bit field may correspond to a TID value from 0 to 7. If the value of each bit is 1, it indicates that the TID corresponding to that bit is acceptable. The value of the subfield is 11111111 2b In this case, it can be shown that the TID value is allowed to range from 0 to 7. Furthermore, in another specific embodiment, the value of the subfield is 11111111 2b In this case, it can be indicated that the transmission of all TIDs is permitted. In yet another specific embodiment, information about the TID may be indicated by a 16-bit field. Specifically, each bit in the 16-bit field may correspond to a TID value from 0 to 15. If the value of each bit is 1, it can be indicated that the TID corresponding to that bit is permitted.

[0246] Furthermore, the second AP can signal EDCA parameters used in backoff procedures for subchannels other than the 20MHz main channel. Specifically, the control frame described above can include information regarding EDCA parameters used in backoff procedures for subchannels other than the 20MHz main channel. The first station (STA1) uses the signaled backoff parameters to perform the backoff procedure on a subchannel instead of the 20MHz main channel. In a specific embodiment, even if the first station (STA1) is using MU EDCA parameters, the first station (STA1) can use the signaled backoff parameters to perform the backoff procedure on a subchannel instead of the 20MHz main channel. At this time, after the first station (STA1) completes the backoff procedure on a subchannel other than the 20MHz main channel, or when performing the backoff procedure on the 20MHz main channel, the first station (STA1) can again use MU-EDCA parameters to perform the backoff procedure.

[0247] In the embodiment shown in Figure 26, 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 first AP (AP1) and the first station (STA1) are connected by a first link (Link1), and the second AP (AP2) and the second station (STA2) are connected by a second link (Link1). At this time, it is detected that the 20MHz main channel of the first AP (AP1) is not idle. The second AP (AP2) transmits information regarding the reception standby status of the first AP (AP1), such as information regarding the reception standby subchannel and reception standby time, to the second station (STA2). At this time, the second AP (AP2) transmits information regarding the reception standby status using a control frame over the second link (Link2). At this time, the receiver address of the control frame may be the first station (STA1). In yet another specific embodiment, the receiver address of the control frame may be the MAC address of a non-AP multilink device including the first station (STA1) and the second station (STA2). In yet another specific embodiment, the receiver address of the control frame may be a group address. The first station (STA1) performs a backoff procedure on a subchannel other than the 20MHz main channel (P20). After the backoff procedure is successful, it sends a PPDU to the first AP (AP1).

[0248] In an embodiment of the present invention, an AP may park a station coupled to the AP on a segment other than the 80MHz main channel. In this case, the station coupled to the AP can operate the subchannel within the segment where the station is parked as if it were the 20MHz main channel. Specifically, the station coupled to the AP can search for the PPDU preamble in the segment where the station is parked. Furthermore, even if the AP transmits a PPDU with a 320MHz bandwidth, the station coupled to the AP can receive it as if it were a PPDU with an 80MHz bandwidth or a PPDU with a 160MHz bandwidth. This is because, as mentioned above, the signaling fields of the PPDU, such as the U-SIG field and the EHT-SIG field, can be transmitted with different content for each segment. Also, since the signaling fields can be transmitted with different content for each segment, it is possible to prevent the length of the signaling fields from becoming excessively long.

[0249] A subchannel used by a station connected to an AP as a 20MHz primary channel within a parked segment is called a virtual primary channel. In this case, preamble puncturing does not need to be performed on the virtual primary channel. Furthermore, one virtual primary channel may be designated for each segment. Specifically, the lowest 20MHz channel in a segment may be designated as the virtual primary channel. If the AP cannot transmit the PPDU preamble on the virtual primary channel in any one segment, the AP can puncture that segment. In yet another specific embodiment, if the AP cannot transmit the PPDU preamble on the virtual primary channel in any one segment, the AP can transmit the PPDU to stations not parked in that segment. That is, if the AP cannot transmit the PPDU preamble on the virtual primary channel in any one segment, stations parked in that segment do not need to receive the PPDU. Also, if the AP punctures any one segment, the AP does not need to trigger uplink transmissions from stations parked in that segment. Specifically, the AP does not need to send a trigger frame to assign a RU for uplink transmission to a station parked in that segment.

[0250] If a station parked on a segment other than the 80MHz main channel is restricted to accessing the channel on a 20MHz main channel other than the virtual main channel, the AP may use different channels for transmitting and for detecting the PPDU preamble. Similarly, the station may use different channels for performing backoff for uplink transmission and for detecting the PPDU preamble. Therefore, the AP may perform backoff for a station parked on a segment other than the 80MHz main channel, but may not receive the PPDU transmitted by that station. Consequently, the AP may allow a station parked on a segment other than the 80MHz main channel to perform backoff procedures for uplink transmission on the segment in which it is parked. This will be explained using Figure 27.

[0251] Figure 27 shows that the AP of the AP multilink device according to an embodiment of the present invention allows a station parked on a segment other than the 80MHz main channel to perform a backoff procedure for uplink transmission on the segment in which the station is parked.

[0252] When a station detects that an Inter-BSS PPDU is being transmitted on the 20MHz main channel, it can allow stations parked on segments other than the 80MHz main channel to perform a backoff procedure for uplink transmission on the virtual main channel. In this case, the AP can determine which segment the station should perform the backoff procedure for uplink transmission on, based on the bandwidth of the Inter-BSS PPDU transmitted on the 20MHz main channel. Specifically, the AP can determine which segments the station should perform the backoff procedure for uplink transmission on are those on which no Inter-BSS PPDU is transmitted. In this case, the AP can allow stations parked on the determined segment to perform the backoff procedure using the virtual main channel of the determined segment. In this case, the AP can allow only some of the stations parked on the determined segment to perform the backoff procedure using the virtual main channel. For example, if an Inter-BSS PPDU with a bandwidth of 160MHz is transmitted on two segments, the AP can allow stations parked on the remaining two segments to perform the backoff procedure using the virtual main channel. In this case, the AP can only allow backoff using the virtual main channel for stations parked in one of the two segments.

[0253] Furthermore, the AP can signal segments for which backoff procedures are permitted using the virtual main channel using a 2-bit subfield. For convenience of explanation, segments for which backoff procedures are permitted using the virtual main channel are called designated segments. In this case, the subfield can indicate the index of the designated segment. For example, if the value of the subfield is 0, the subfield can indicate that the segment corresponding to the lowest frequency band is the designated segment. If the value of the subfield is 3, the subfield can indicate that the segment corresponding to the highest frequency band is the designated segment. In another specific embodiment, if the value of the subfield is 0, the subfield can indicate that the segment corresponding to the 80MHz main channel is the designated segment. In this case, if the value of the subfield is 1, the subfield can indicate that the segment corresponding to the 80MHz subchannel is the designated segment. Also, if the value of the subfield is 2 or 3, the subfield can indicate that each of the two segments corresponding to the 160MHz subchannel is the designated segment.

[0254] Furthermore, the AP can signal to the station PPDU reception waiting time information, which is information about the time the AP waits for PPDU reception on the virtual primary channel. Specifically, the AP can signal PPDU reception waiting time information to the station along with a specified segment. At this time, the station can determine the length of the PPDU to transmit based on the PPDU reception waiting time information. Specifically, the station can determine the length of the PPDU so that the PPDU transmission completion time does not exceed the PPDU reception waiting time. In yet another specific embodiment, the station can determine the length of the PPDU so that the completion time of the PPDU and the response to the PPDU does not exceed the PPDU reception waiting time. At this time, the response to the PPDU may be an ACK, for example, an ACK frame and a BlockACK frame.

[0255] Furthermore, the AP can signal to the station the type of traffic transmitted based on the backoff procedure on the virtual main channel. The specific operation of the AP and station may be the same as that of the AP and station in the embodiment described in Figure 26. The AP can also signal to the station the EDCA parameters that the station will use when performing the backoff procedure on the virtual main channel. The specific operation of the AP and station may be the same as that of the AP and station in the embodiment described in Figure 26. In this case, the EDCA parameters used when the station performs the backoff procedure on the 20MHz main channel and the EDCA parameters used when the station performs the backoff procedure on the virtual main channel may be independent. For example, the backoff counter used when the station performs the backoff procedure on the 20MHz main channel and the backoff counter used when the station performs the backoff procedure on the virtual main channel may be independent.

[0256] Furthermore, the AP multilink device can transmit the aforementioned information to a station coupled with the first AP via the second AP of the AP multilink device.

[0257] Furthermore, stations parked in segments other than the segment containing the virtual primary channel for which the AP is permitted to perform a backoff procedure can enter a power-saving state based on the aforementioned receive waiting time information. Specifically, stations parked in segments other than the segment containing the virtual primary channel for which the AP is permitted to perform a backoff procedure can maintain a power-saving state during the receive waiting time.

[0258] In the embodiment shown in Figure 27, the AP multilink device includes a first AP and a second AP. At this time, the first AP senses that an Inter-BSS PPDU is being transmitted on the first AP's 20MHz main channel (P20). The first AP (AP1) signals via the second AP (AP2) that a backoff procedure for uplink transmission is permitted on the virtual main channel of the second segment (Segment2), which is not the first segment (Segment1) containing the 20MHz main channel (P20). At this time, in addition to indicating that a backoff procedure for uplink transmission is permitted in the second segment (Segment2), the first AP (AP1) also signals the link on which the first AP (AP1) operates, the uplink transmission waiting time (Time limit), the TID of the traffic transmitted in the uplink, and the EDCA parameters used in the backoff procedure for uplink transmission.

[0259] 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.

[0260] 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.

[0261] 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.

Claims

1. A multilink device using multiple links, Transmitting and receiving unit; and Including the processor, The processor is configured to receive a first PPDU (physical layer protocol data unit) on the first link of the plurality of links from a station that is a TXOP (transmission opportunity) holder or an SP (service period) source, including an RD (reverse direction) grant and an AC (access category) restriction signaling. An AC or TID (traffic identifier) ​​is mapped to the transmission of the multilink device on the first link of the plurality of links, and the multilink device transmits a frame on the first link based on the mapped AC or TID. The aforementioned processor, The AC limiting signaling indicates that any TID of a data frame included in the second PPDU is acceptable, and when the multilink device includes a data frame in the second PPDU, it does not include a data frame in the second PPDU that corresponds to a TID not mapped to the transmission of the multilink device in the first link, and does include a data frame in the second PPDU that corresponds to a TID mapped to the transmission of the multilink device in the first link. The first link is configured to transmit the second PPDU to the station as a response to the first PPDU, The AC limiting signaling is included in the command and status Control subfield of the frame included in the first PPDU, in a multilink device.

2. The aforementioned processor, The AC limiting signaling indicates that the AC or TID of a frame included in the second PPDU is limited, and when the multilink device includes a data frame in the second PPDU, it does not include in the second PPDU any data frame that is not mapped to the transmission of the multilink device in the first link or that corresponds to a TID or AC with a lower priority than the AC or TID of a frame included in the first PPDU, but it does include in the second PPDU any data frame that is mapped to the transmission of the multilink device in the first link and that corresponds to a TID or AC with the same priority as or higher than the AC or TID of a frame included in the first PPDU. The multilink device according to claim 1, configured as described above.

3. The multilink device according to claim 2, wherein when the first PPDU includes a plurality of frames, the priority of the AC or TID of the frames included in the second PPDU is the lowest priority among the priorities of the plurality of frames.

4. The aforementioned processor, When the second PPDU includes a BlockAck frame, the AC of the BlockAck frame is determined based on the TID field of the BlockAck frame. When the second PPDU includes a BlockAckReq frame, the AC of the BlockAckReq frame is determined based on the TID field of the BlockAckReq frame. The multilink device according to claim 1, configured as described above.

5. A method for operating a multilink device that uses multiple links, A step in which a first link of the plurality of links receives a first PPDU (physical layer protocol data unit) including a reverse direction (RD) grant and access category (AC) restriction signaling from a station that is a TXOP (transmission opportunity) holder or an SP (service period) source, wherein an AC or TID (traffic identifyr) is mapped to the transmission of the multilink device on the first link of the plurality of links, and the multilink device transmits a frame on the first link based on the mapped AC or TID; The AC limiting signaling indicates that any TID of a data frame included in the second PPDU is acceptable, and when the multilink device includes a data frame in the second PPDU, it does not include in the second PPDU any data frame corresponding to a TID not mapped to the transmission of the multilink device in the first link, and includes in the second PPDU any data frame corresponding to a TID mapped to the transmission of the multilink device in the first link; and The first link includes the step of transmitting the second PPDU to the station as a response to the first PPDU, The AC limit signaling is a method in which the command and status control subfield of the frame included in the first PPDU is included.

6. The step of transmitting the second PPDU to the station is: The method according to claim 5, wherein the AC limiting signaling indicates that the AC or TID of a frame included in the second PPDU is limited, and when the multilink device includes a data frame in the second PPDU, the second PPDU does not include data frames that are not mapped to the transmission of the multilink device in the first link or that correspond to a TID or AC with a priority lower than the priority of the AC or TID of a frame included in the first PPDU, and the second PPDU includes data frames that are mapped to the transmission of the multilink device in the first link and that correspond to a TID or AC with the same priority as or higher than the priority of the AC or TID of a frame included in the first PPDU.

7. The method according to claim 6, wherein when the multilink device receives a plurality of frames from the station, the priority of the AC or TID of the frame included in the first PPDU is the lowest priority among the priorities of the plurality of frames.

8. The step of transmitting the second PPDU to the station is: When the second PPDU includes a BlockAck frame, the steps include determining the AC of the BlockAck frame based on the TID field of the BlockAck frame, The method according to claim 5, further comprising the step of determining the AC of the BlockAckReq frame based on the TID field of the BlockAckReq frame when the second PPDU includes a BlockAckReq frame.

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