Wireless communication method using multi-link and wireless communication terminal using the same

Abstract

A method for a station (STA) to transmit a frame in a wireless communication system is disclosed. The STA according to the present invention receives a trigger frame instructing uplink transmission from an access point (AP), and transmits a physical layer protocol data unit (PPDU) to the AP and / or other STAs in the shared TXOP based on the trigger frame. At this time, the trigger frame is used to share a part or all of a transmission opportunity (TXOP) acquired by the AP to the STA. In addition, the PPDU includes duration information instructing a TXOP for transmitting the PPDU, and the duration information is set based on the shared TXOP.

Description

Technical Field

[0001] The present invention relates to a wireless communication method using multi-links and a wireless communication terminal using the same, and more particularly, to a method and a terminal for setting a TXOP to transmit and receive data.

Background Art

[0002] Recently, as the popularity of mobile devices has expanded, wireless LAN (Local Area Network) technology that can provide fast wireless Internet services to these devices 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 band, various technology standards have been put into practical use or are under development. First, IEEE 802.11b uses the frequency band of 2.4 GHz and supports a communication speed of up to 11 Mbps. IEEE 802.11a, which was commercialized after IEEE 802.11b, uses the frequency band of 5 GHz instead of the 2.4 GHz band, thereby reducing the impact on interference compared to the relatively congested 2.4 GHz band frequency, and improving the communication speed up to 54 Mbps using OFDM (Orthogonal Frequency Division Multiplexing) technology. However, IEEE 802.11a has a disadvantage in that its communication distance is shorter than that of IEEE 802.11b. And IEEE 802.11g uses the frequency band of 2.4 GHz like IEEE 802.11b to implement a communication speed of up to 54 Mbps, satisfies backward compatibility, and has received considerable attention, but it is also superior to IEEE 802.11a in terms of communication distance.

[0004] And, as a technical standard established to overcome the limitations regarding communication speed pointed out as vulnerabilities in Wi-Fi, there is IEEE 802.11n. The purpose of IEEE 802.11n is to increase the speed and reliability of the network and extend the operating distance of the wireless network. Specifically, IEEE 802.11n supports a high throughput (HT) with a maximum data processing speed of 540 Mbps or more, and is based on the MIMO (Multiple Inputs and Multiple Outputs) technology that uses multiple antennas at both the transmitting and receiving ends to minimize transmission errors and optimize the data speed. Also, this standard uses a coding method that transmits multiple copies of redundant transcripts to increase the reliability of the data.

[0005] As the popularity of wireless LANs has been activated and the applications using them have become diversified, there is a growing need for a new wireless LAN system that supports a processing rate (Very High Throughput, VHT) higher than the data processing speed supported by IEEE 802.11n. Among them, IEEE 802.11ac supports a wide bandwidth (80 MHz to 160 MHz) at the 5 GHz frequency. Although the IEEE 802.11ac standard is defined only in the 5 GHz band, the initial 11ac chipset is considered to support operation in the 2.4 GHz band for backward compatibility with conventional 2.4 GHz band products. Theoretically, according to this standard, the speed of a wireless LAN with multiple stations can be up to 1 Gbps at minimum and the maximum single-link speed can be up to 500 Mbps at minimum. This is achieved by expanding the concepts of wireless interfaces accepted in 802.11n, such as a wider wireless frequency bandwidth (up to 160 MHz), more MIMO spatial streams (up to 8), multi-user MIMO, and high-density modulation (up to 256QAM). Also, as a method of transmitting data using the 60 GHz band instead of the conventional 2.4 GHz / 5 GHz bands, there is IEEE 802.11ad. IEEE 802.11ad is a transmission standard that uses beamforming technology to provide a speed of up to 7 Gbps and is suitable for streaming high-bitrate videos such as large-capacity data and uncompressed HD videos. However, the 60 GHz frequency band has the disadvantage that it is difficult for obstacles to pass through and it can only be used between devices in a short-distance space.

[0006] On the other hand, as a wireless LAN standard after 802.11ac and 802.11ad, the IEEE 802.11ax (High Efficiency WLAN, HEW) standard has been developed and is in the completion stage to provide high-efficiency and high-performance wireless LAN communication technology in a high-density environment where APs and terminals are concentrated. In an 802.11ax-based wireless LAN environment, it is necessary to provide high-frequency efficiency communication indoors / outdoors in the presence of a high density of stations and APs (Access Points), and various technologies have been developed to implement this.

[0007] In addition, in order to support new multimedia applications such as high-quality videos and real-time games, a new Wi-Fi standard for increasing the maximum transmission speed has been started to be developed. In the 7th generation Wi-Fi standard IEEE 802.11be (Extremely High Throughput, EHT), standard development is in progress with the goal of supporting a maximum transmission rate of 30 Gbps through a wider bandwidth, increased spatial streams, and multi-AP cooperation in the 2.4 / 5 / 6 GHz bands. In IEEE 802.11be, technologies such as a 320 MHz bandwidth, multi-link operation, multi-access point (multi-AP) operation, and hybrid automatic repeat request (HARQ) have been proposed.

[0008] The multi-link operation can be operated in various forms depending on its operation method and implementation method. At this time, there is a possibility that problems that did not occur in the conventional IEEE 802.11-based Wi-Fi communication operation may occur, so a definition of the detailed operation method in the multi-link operation is necessary.

[0009] On the other hand, the background art of the invention is created to enhance the understanding of the background of the invention, and includes content that is not prior art already known to those having ordinary knowledge in the field to which this technology belongs.

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] An object of the present invention is to provide a method and apparatus for transmitting and receiving data using the setting of a transmission opportunity (TXOP) in a multi-link operation.

[0011] Furthermore, an object of the present invention is to provide a method and apparatus for a non-AP STA to transmit and receive data by sharing a TXOP (Transmission Opportunity) set by an AP (Access Point).

[0012] In addition, an object of the present invention is to provide a method and apparatus for setting a NAV (Network Allocation Vector) for a non-AP STA to transmit and receive data within a shared TXOP.

[0013] The technical problems to be solved in this specification are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those with ordinary knowledge in the technical field to which the present invention pertains from the following description.

Means for Solving the Problems

[0014] A STA (Station) in a wireless communication system includes a transceiver; and a processor for controlling the transceiver. The processor receives a trigger frame for instructing uplink transmission from an AP (Access Point). The trigger frame is used to share part or all of a transmission opportunity (TXOP) acquired by the AP with the STA. Based on the trigger frame, a PPDU (Physical layer Protocol Data Unit) is transmitted to the AP and / or other STAs within the shared TXOP. The PPDU includes duration information indicating a TXOP for transmitting the PPDU, and the duration information is set based on the shared TXOP.

[0015] In addition, in the present invention, the end point of the duration indicated by the duration information is the same as the end point of the shared TXOP.

[0016] Also, in the present invention, the duration indicated by the duration information ends before the end of the shared TXOP.

[0017] Also, in the present invention, when a NAV (network allocation vector) is set by a frame transmitted by the AP within the TXOP, the PPDU is transmitted regardless of the set NAV within the shared TXOP.

[0018] Also, in the present invention, when a NAV and a NAV timeout period indicating the end time of the NAV are set within the shared TXOP based on the trigger frame by yet another STA, even when the NAV timeout period expires within the shared TXOP, the NAV set by the yet another STA within the shared TXOP is not released due to the expiration of the NAV timeout period.

[0019] Also, in the present invention, the trigger frame includes a subfield indicating whether or not the TXOP is shared by the trigger frame.

[0020] Also, in the present invention, when the subfield indicates sharing of the TXOP, the value of the subfield indicates whether or not communication is possible with the other STA within the shared TXOP.

[0021] Also, in the present invention, the trigger frame includes a type field indicating the type of the trigger frame, and sharing of part or all of the TXOP is set by the type of the trigger frame according to the type field.

[0022] The present invention also provides a method including: receiving a trigger frame for instructing uplink transmission from an AP (Access Point), where the trigger frame is used to share part or all of a transmission opportunity (TXOP) obtained by the AP with the STA; and based on the trigger frame, transmitting a PPDU (Physical layer Protocol Data Unit) to the AP and / or another STA within the shared TXOP, where the PPDU includes duration information for instructing a TXOP for transmitting the PPDU, and the duration information is set based on the shared TXOP.

Advantages of the Invention

[0023] According to an embodiment of the present invention, by sharing a TXOP set by an AP with a non-AP STA, there is an effect that the non-AP STA can efficiently transmit and receive data.

[0024] Also, according to an embodiment of the present invention, by setting a NAV for a non-AP STA to transmit and receive data within a shared TXOP based on the shared TXOP, or by interpreting a set NAV by the shared TXOP, there is an effect that data can be efficiently transmitted.

[0025] The effects obtained from the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those of ordinary skill in the technical field to which the present invention pertains from the following description.

Brief Description of the Drawings

[0026]

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Mode for Carrying Out the Invention

[0027] The terms used in this specification are selected as generally widely used terms as much as possible considering the functions in the present invention. However, this may vary depending on the intentions, conventions of those skilled in the relevant technical field, or the emergence of new technologies. In addition, in certain cases, there are terms arbitrarily selected by the applicant. In such cases, the meaning thereof is described in the explanatory part of the corresponding invention. Therefore, it is clarified that the terms used in this specification should not be merely the names of the terms, but should be interpreted based on the substantial meanings of the terms and the content throughout this specification.

[0028] Throughout the specification, if a certain configuration is described as "connected" to another configuration, this includes not only the case of "directly connected", but also the case of being "electrically connected" with other components interposed therebetween. Also, if a certain component "includes" a specific component, this means that it may further include other components rather than excluding other components, unless otherwise stated to the contrary. In addition, the limiting terms "above" or "below" based on a specific critical value may be appropriately replaced by "exceeding" or "less than" respectively according to the embodiments. Hereinafter, in the present invention, a field and a sub-field may be used in the same meaning.

[0029] FIG. 1 is a diagram showing a wireless LAN system according to an embodiment of the present invention.

[0030] The wireless LAN system includes one or more basic service sets (BSSs), and a BSS indicates 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). FIG. 1 shows an infrastructure BSS among them.

[0031] As shown in FIG. 1, infrastructure BSSs BSS1 and BSS2 include one or more stations STA1, STA2, STA3, STA4, STA5, access points AP-1 and AP-2 which are stations providing a distribution service, and a distribution system DS that connects the plurality of access points AP-1 and AP-2.

[0032] A station (STA) is any device including a Medium Access Control (MAC) according to the provisions of the IEEE 802.11 standard and a physical layer interface for a wireless medium. In a broad sense, it includes not only non-access point non-AP stations but also all access points AP. Also, in this specification, the term "terminal" is used to refer to a non-AP or an AP, or both. A station for wireless communication includes a processor and a communication unit, and further includes a user interface unit, a display unit, etc. according to embodiments. The processor generates a frame to be transmitted via a wireless network, or processes a frame received via the wireless network, and performs various processes for controlling the station. Then, the communication unit is functionally connected to the processor and transmits and receives frames via the wireless network for the station. In the present invention, the terminal is used as a term including a user equipment (UE).

[0033] An Access Point (AP) is an entity that provides a connection to a Distribution System (DS) via a wireless medium for stations associated with it. In an Infrastructure BSS, communication between non-AP stations is generally done via the AP, but direct communication between non-AP stations is possible if a direct link is set up. On the other hand, in the present invention, the AP is used as a concept that includes a PCP (Personal BSS Coordination Point), but in a broad sense, it includes concepts such as a centralized controller, a Base Station (BS), a Node B, a BTS (Base Transceiver System), or a site controller. In the present invention, the AP is also referred to as a base wireless communication terminal, and the base wireless communication terminal is used as a term that includes, in a broad sense, an AP, a base station, an eNB (eNodeB), and a Transmission Point (TP). Moreover, the base wireless communication terminal includes various forms of wireless communication terminals that allocate communication medium resources and perform scheduling in communication with a plurality of wireless communication terminals.

[0034] A plurality of Infrastructure BSSs are connected to each other via a Distribution System (DS). At this time, a plurality of BSSs connected via the distribution system are called an Extended Service Set (ESS).

[0035] FIG. 2 is a diagram showing an Independent BSS, which is a wireless LAN system according to another embodiment of the present invention. In the embodiment of FIG. 2, the same or corresponding parts as those in the embodiment of FIG. 1 are not described repeatedly.

[0036] Since the BSS3 shown in FIG. 2 is an independent BSS and does not include an AP, all stations (STA6, STA7) are not connected to the AP. An independent BSS does not allow connection to a distribution system and forms a self - contained network. In an independent BSS, each station (STA6, STA7) is directly connected to each other.

[0037] FIG. 3 is a block diagram showing the configuration of a station 100 according to an embodiment of the present invention. As shown, the station 100 according to the embodiment of the present invention includes a processor 110, a communication unit 120, a user interface unit 140, a display unit 150, and a memory 160.

[0038] First, the communication unit 120 transmits and receives wireless signals such as wireless LAN packets, and may be incorporated into or externally attached to the station 100. According to an embodiment, the communication unit 120 can include at least one communication module using different frequency bands. For example, the communication unit 120 can include communication modules for different frequency bands such as 2.4 GHz, 5 GHz, 6 GHz, and 60 GHz. According to one embodiment, the station 100 can be provided with 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 perform wireless communication with an AP or an external station based on the wireless LAN standard of the frequency band supported by the communication module. The communication unit 120 can operate only one communication module at a time or operate a plurality of communication modules together according to the performance and requirements of the station 100. When the station 100 includes a plurality of communication modules, each communication module may be provided in an independent form, or a plurality of modules may be integrated as one chip. In an embodiment of the present invention, the communication unit 120 can represent an RF (Radio Frequency) communication module that processes RF signals.

[0039] Next, the user interface 140 includes various forms of input / output means provided in the station 100. That is, the user interface unit 140 receives the user's input using various input means, and the processor 110 controls the station 100 based on the received user input. Also, the user interface unit 140 performs an output based on the instruction of the processor 110 using various output means.

[0040] Next, the display unit 150 outputs an image on the display screen. The display unit 150 outputs various display objects such as content performed by the processor 110 or a user interface based on the control instruction of the processor 110. Also, the memory 160 stores a control program used in the station 100 and various data thereby. Such a control program includes a connection program necessary for the station 100 to connect to an AP or an external station.

[0041] The processor 110 of the present invention performs various instructions or programs and processes the data inside the station 100. Also, the processor 110 controls each unit of the station 100 described above and controls the transmission and reception of data between the units. According to an embodiment of the present invention, the processor 110 executes a program for connection with the AP stored in the memory 160 and receives a communication setting message transmitted by the AP. Also, the processor 110 reads information regarding the priority conditions of the station 100 included in the communication setting message and requests a connection regarding the AP based on the information regarding 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 may refer to a control unit for individually controlling some configurations of the station 100, for example, the communication unit 120, etc., according to an embodiment. That is, the processor 110 may be a modem, or a modulator and / or demodulator, for modulating and demodulating the radio signals transmitted and received from the communication unit 120. The processor 110 controls various operations of the radio signal transmission and reception of the station 100 according to an embodiment of the present invention. Detailed embodiments thereof will be described later.

[0042] The station 100 shown in FIG. 3 is a block diagram according to an embodiment of the present invention, and the separately shown blocks logically distinguish the elements of the device. Therefore, the above-described elements of the device may be attached to one chip or a plurality of chips according to the design of the device. For example, the processor 110 and the communication unit 120 may be integrated and implemented on one chip, or may be implemented on separate chips. Also, in an embodiment of the present invention, some configurations of the station 100, for example, the user interface unit 140 and the display unit 150, etc., may be selectively provided in the station 100.

[0043] FIG. 4 is a block diagram showing the configuration of AP200 according to an embodiment of the present invention. As shown, AP200 according to the embodiment of the present invention includes a processor 210, a communication unit 220, and a memory 260. In FIG. 4, redundant descriptions are omitted for parts of the configuration of AP200 that are the same as or corresponding to the configuration of station 100 in FIG. 3.

[0044] Referring to FIG. 4, AP 200 according to the present invention includes a communication unit 220 for operating a BSS in at least one frequency band. As described above in the embodiment of FIG. 3, the communication unit 220 of the AP 200 can also include a plurality of communication modules using different frequency bands. That is, AP 200 according to the embodiment of the present invention can include two or more communication modules using different frequency bands, for example, any of 2.4 GHz, 5 GHz, 6 GHz, and 60 GHz. Preferably, 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 perform wireless communication with a station based on the wireless LAN standard of the frequency band supported by the communication module. The communication unit 220 can operate only one communication module at a time or operate a plurality of communication modules simultaneously according to the performance and requirements of AP 200. In the embodiment of the present invention, the communication unit 220 can represent an RF (Radio Frequency) communication module that processes RF (Radio Frequency) signals.

[0045] Next, the memory 260 stores the control program used in the AP200 and various data thereby. Such a control program includes a connection program for managing the connection of the stations. Further, the processor 210 controls each unit of the AP200 and controls the transmission and reception of data between the units. According to an embodiment of the present invention, the processor 210 executes a program for connection to the stations stored in the memory 260 and transmits a communication setting message for one or more stations. At this time, the communication setting message includes information regarding the connection priority conditions of each station. Further, the processor 210 performs connection setting in response to a connection request from the station. According to one embodiment, the processor 210 is a modem or a modulation / demodulation unit that modulates and demodulates a radio signal transmitted and received from the communication unit 220. The processor 210 controls various operations of the radio signal transmission and reception of the AP200 according to an embodiment of the present invention. Detailed embodiments thereof will be described later.

[0046] FIG. 5 is a diagram schematically showing a process in which a STA sets a link with an AP.

[0047] Referring to FIG. 5, the link between the STA100 and the AP200 is set through three major steps: scanning, authentication, and association. First, the scanning step is a step in which the STA100 obtains connection information of the BSS operated by the AP200. As a method for performing scanning, there are a passive scanning method of obtaining information by utilizing only the beacon message S101 periodically transmitted by the AP200, and an active scanning method in which the STA100 transmits a probe request to the AP (S103), receives a probe response from the AP (S105), and obtains connection information.

[0048] The STA100 that has successfully received the wireless connection information in the scanning step transmits an authentication request to S107a, receives an authentication response from the AP200 to S107b, and performs an authentication step. After the authentication step is performed, the STA100 transmits an association request to S109a, receives an association response from the AP200 to S109b, and performs an association step. In this specification, "association" basically means a wireless connection, but the present invention is not limited to this, and the broad meaning of "association" includes all wireless connections and wired connections.

[0049] On the other hand, an additional 802.1X-based authentication step S111 and an IP address acquisition step S113 via DHCP are performed. In FIG. 5, the server 300 is a server that processes 802.1X-based authentication with the STA100, and may be physically connected to the AP200 or exist as a separate server.

[0050] FIG. 6 is a diagram showing the CSMA (Carrier Sense Multiple Access) / CA (Collision Avoidance) method used in wireless LAN communication.

[0051] A terminal performing wireless LAN communication checks whether a channel is in an occupied state (busy) by performing carrier sensing before transmitting data. If a wireless signal with a certain intensity or higher is sensed, the corresponding channel is determined to be in an occupied state, and the terminal delays access to the corresponding channel. Such a process is called Clear Channel Assessment (CCA), and the level for determining the presence or absence of sensing of the corresponding signal is called the CCA threshold. If a wireless signal equal to or higher than the CCA threshold received by the terminal has the corresponding terminal as the receiver, the terminal processes the received wireless signal. On the other hand, if no wireless signal is sensed from the corresponding channel or a wireless signal with an intensity lower than the CCA threshold is sensed, the channel is determined to be in an idle state.

[0052] If the channel is determined to be in an idle state, each terminal having data to transmit performs a backoff procedure after a time of IFS (Inter Frame Space) according to the situation of each terminal, for example, AIFS (Arbitration IFS), PIFS (PCF IFS), etc. According to an embodiment, the AIFS is used as a configuration to replace the conventional DIFS (DCF IFS). Each terminal waits while decreasing the slot time by the random number determined for the corresponding terminal during the interval of the idle state of the channel, and the terminal that has exhausted all the slot times attempts access to the corresponding channel. Thus, the section in which each terminal performs the backoff procedure is called a contention window section.

[0053] If a specific terminal successfully accesses the channel, the corresponding terminal transmits data via 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. According to one embodiment, the new random number newly assigned to each terminal is determined within a range (2*CW) that is twice the range (contention window, CW) of the random number previously assigned to the corresponding terminal. On the other hand, each terminal performs a further backoff procedure in the next contention window period to attempt access. At this time, each terminal performs the backoff procedure from the slot time remaining in the previous contention window period. In this way, each terminal performing wireless LAN communication can avoid mutual collisions with respect to a specific channel.

[0054] Hereinafter, in the present invention, a terminal can be referred to as a non-AP STA, AP STA, AP, STA, receiving device, or transmitting device, and the present invention is not limited thereto. Also, in the present invention, an AP STA can be referred to as an AP.

[0055] <Examples of Various PPDU Formats>

[0056] FIG. 7 shows an example of various standard-generation PPDU (PLCP Protocol Data Unit) formats. More specifically, FIG. 7(a) shows an embodiment of a legacy PPDU format based on 802.11a / g, FIG. 7(b) shows an embodiment of a HE PPDU format based on 802.11ax, and FIG. 7(c) shows an embodiment of a non-legacy PPDU (i.e., EHT PPDU) format based on 802.11be. Also, FIG. 7(d) shows the detailed field configurations of L-SIG and RL-SIG commonly used in the PPDU formats.

[0057] Referring to FIG. 7(a), the preamble of the legacy PPDU includes an L-STF (Legacy Short Training field), an L-LTF (Legacy Long Training field), and an L-SIG (Legacy Signal field). In an embodiment of the present invention, the L-STF, L-LTF, and L-SIG can be referred to as the legacy preamble.

[0058] Referring to FIG. 7(b), the preamble of the HE PPDU further includes the legacy preamble, an RL-SIG (Repeated Legacy Short Training field), an HE-SIG-A (High Efficiency Signal A field), an HE-SIG-B (High Efficiency Signal B field), an HE-STF (High Efficiency Short Training field), and an HE-LTF (High Efficiency Long Training field). In an embodiment of the present invention, the RL-SIG, HE-SIG-A, HE-SIG-B, HE-STF, and HE-LTF can be referred to as the HE preamble. The specific configuration of the HE preamble may be deformed according to the HE PPDU format. For example, the HE-SIG-B may be used only in the HE MU PPDU format.

[0059] Referring to FIG. 7(c), the preamble of the EHT PPDU further includes, in the legacy preamble, 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 an embodiment of the present invention, the 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 deformed according to the EHT PPDU format. For example, EHT-SIG-A and EHT-SIG-B may be used only in some formats of the EHT PPDU format.

[0060] The L-SIG field included in the preamble of the PPDU applies 64 FFT OFDM and is composed of a total of 64 subcarriers. Among these, 48 subcarriers excluding the guard subcarriers, DC subcarriers, and pilot subcarriers are used for data transmission of L-SIG. Since BPSK and MCS (Modulation and Coding Scheme) with a rate of 1 / 2 are applied to L-SIG, it can include a total of 24 bits of information. FIG. 7(d) shows the 24-bit information configuration of L-SIG.

[0061] Referring to FIG. 7(d), the L-SIG includes an L_RATE field and an L_LENGTH field. The L_RATE field is composed of 4 bits and indicates the MCS used for data transmission. Specifically, the L_RATE field indicates one value among the transmission speeds of 6 / 9 / 12 / 18 / 24 / 36 / 48 / 54 Mbps, which is a combination of modulation methods such as BPSK / QPSK / 16-QAM / 64-QAM and coding rates such as 1 / 2, 2 / 3, 3 / 4. Combining the information of the L_RATE field and the L_LENGTH field can indicate the total length of the PPDU. In the non-legacy PPDU format, the L_RATE field is set to the minimum speed of 6 Mbps.

[0062] The unit of the L_LENGTH field is bytes. A total of 12 bits are allocated and can signal up to 4095, and in combination with the L_RATE field, it can indicate the length of the corresponding PPDU. At this time, the legacy terminal and the non-legacy terminal can interpret the L_LENGTH field in different ways.

[0063] First, the method for a legacy terminal or a non-legacy terminal to interpret the length of the corresponding PPDU using the L_LENGTH field is as follows. When the value of the L_RATE field is set to indicate 6 Mbps, 3 bytes (i.e., 24 bits) may be transmitted during the 4 us of one symbol duration of 64 FFT. Therefore, adding the 3 bytes corresponding to the SVC field and the Tail field to the L_LENGTH field value and dividing this by 3 bytes, which is the transmission amount of one symbol, the number of 64 FFT reference symbols after L-SIG is obtained. After multiplying the obtained number of symbols by 4 us, which is one symbol duration, and then adding the 20 us required for transmitting L-STF, L-LTF, and L-SIG, the length of the corresponding PPDU, that is, the reception time (RXTIME) is obtained. Expressed as a mathematical formula, it is as shown in Equation 1 below.

[0064]

Equation

Number

[0065]

Number

[0066] Here, TXTIME is the total transmission time that constitutes the PPDU and is as shown in Equation 3 below. At this time, TX represents the transmission time of X.

[0067]

Number

[0068] Referring to the above equations, the length of the PPDU is calculated based on the ceiling value of L_LENGTH / 3. Therefore, for any k value, three different values of L_LENGTH = {3k + 1, 3k + 2, 3(k + 1)} indicate the same PPDU length.

[0069] Referring to FIG. 7(e), the U-SIG (Universal SIG) field persists in the EHT PPDU and subsequent generations of wireless LAN PPDUs and serves to distinguish which generation of PPDU it is, including 11be. U-SIG is two symbols of 64FFT-based OFDM and can transmit a total of 52 bits of information. Of these, 43 bits excluding the CRC / Tail 9 bits are roughly divided into a VI (Version Independent) field and a VD (Version Dependent) field.

[0070] The VI bit continues to maintain the current bit configuration later, and even if subsequent generations of PPDUs are defined, current 11be terminals can obtain information about the PPDU from the VI field of the PPDU. For this purpose, the VI field is composed of a PHY version, UL / DL, BSS color, TXOP, and Reserved field. The PHY version field is 3 bits and is responsible for sequentially differentiating the 11be and subsequent generations of wireless LAN standards by version. 11be has a value of 000b. The UL / DL field differentiates whether the PPDU is an uplink / downlink PPDU. The BSS color means the BSS identifier defined in 11ax and has a value of 6 bits or more. The TXOP means the transmit opportunity duration that was transmitted in the MAC header, but by adding it to the PHY header, the length of the TXOP included in the PPDU can be inferred without decoding the MPDU and has a value of 7 bits or more.

[0071] The VD field may be composed of signaling information useful only for the 11be version PPDU, fields commonly used in any PPDU format such as the PPDU format and BW, and fields defined differently for each PPDU format. The PPDU format is a discriminator that distinguishes EHT SU (Single User), EHT MU (Multiple User), EHT TB (Trigger-based), EHT ER (Extended Range) PPDUs, etc. The BW field mainly signals five basic PPDU BW options of 20, 40, 80, 160 (80 + 80), 320 (160 + 160) MHz (BW that can be expressed in the form of 20 * power of 2 can be called the basic BW), and various remaining PPDU BWs constituted by preamble puncturing. Also, after being signaled at 320 MHz, a part of 80 MHz may be signaled in a punctured form. Also, the channel form that has been punctured and deformed may be directly signaled in the BW field, or 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 the puncturing mode can signal a maximum of 3. If the BW field is 4 bits, a total of 16 BW signalings are possible, so the puncturing mode can signal a maximum of 11.

[0072] The fields located after the BW field vary depending on the form and format of the PPDU. The MU PPDU and the SU PPDU may be signaled in the same PPDU format. Before the EHT-SIG field, a field for distinguishing between the MU PPDU and the SU PPDU may be located, and additional signaling for that purpose may be performed. Both the SU PPDU and the MU PPDU contain the EHT-SIG field, but some fields that are unnecessary in the SU PPDU may be compressed. At this time, the information of the fields to which compression is applied may be omitted or may have a size smaller than the size of the original fields included in the MU PPDU. For example, in the case of the SU PPDU, the common fields of the EHT-SIG may be omitted or replaced, the user-specific fields may be replaced, or it may have different configurations such as being reduced to one.

[0073] Alternatively, the SU PPDU may further include a compression field indicating whether it is compressed, and some fields (e.g., the RA field, etc.) may be omitted depending on the value of the compression field.

[0074] When part of the EHT-SIG field of an SU PPDU is compressed, the information contained in the compressed field may be signaled together with uncompressed fields (such as common fields). In the case of an MU PPDU, since it is a PPDU format for simultaneous reception by multiple users, the EHT-SIG field must be transmitted obligatorily after the U-SIG field, and the amount of information to be signaled may be variable. That is, since a plurality of MU PPDUs are transmitted to a plurality of STAs, each STA must recognize the position of the RU to which the MU PPDU is transmitted, the STA to which each RU is assigned, and whether the transmitted MU PPDU is transmitted to itself. Therefore, the AP must transmit the EHT-SIG field including the above information. For this purpose, the U-SIG field signals information for efficiently transmitting the EHT-SIG field, which may be the number of symbols of the EHT-SIG field and / or the MCS which is the modulation method. The EHT-SIG field can include the size and position information of the RUs assigned to each user.

[0075] In the case of an SU PPDU, a plurality of RUs may be assigned to an STA, and the plurality of RUs may be consecutive or non-consecutive. When the RUs assigned to an STA are not consecutive, the STA can efficiently receive the SU PPDU only by recognizing the RUs punctured in the middle. Therefore, the AP can transmit the SU PPDU including information on the punctured RUs among the RUs assigned to the STA (such as the RU puncturing pattern). That is, in the case of an SU PPDU, a puncturing mode field including information indicating whether the puncturing mode is applied and the puncturing pattern in a bitmap format or the like may be included in the EHT-SIG field, and the puncturing mode field can signal the form of the discontinuous channels appearing within the bandwidth.

[0076] The form of the discontinuous channel signaled is restricted and indicates the BW of the SU PPDU and the discontinuous channel information in combination with the value of the BW field. For example, in the case of an SU PPDU, which is a PPDU transmitted only to a single terminal, the STA can recognize the bandwidth assigned to itself from the BW field included in the PPDU, and can recognize the punctured resources among the assigned bandwidths from the puncturing mode field of the U-SIG field or the EHT-SIG field included in the PPDU. In this case, the terminal can receive the PPDU with the resource units other than the specific channels of the punctured resource units. At this time, the plurality of RUs assigned to the STA may be composed of different frequency bands or tones from each other.

[0077] The reason why only the restricted form of the discontinuous channel form is signaled is to reduce the signaling overhead of the SU PPDU. Since puncturing may be performed for each 20 MHz subchannel, when puncturing is performed for a BW having a plurality of 20 MHz subchannels such as 80, 160, and 320 MHz, in the case of 320 MHz, it is necessary to signal the form of the discontinuous channel (including the case where only the end 20 MHz is punctured as discontinuous) by expressing the availability of each of the remaining 15 20 MHz subchannels excluding the primary channel. Using 15 bits to signal the discontinuous channel form of single-user transmission can result in excessive signaling overhead when considering the low transmission rate of the signaling part.

[0078] The present invention proposes a method for signaling the discontinuous channel form of the SU PPDU and shows the discontinuous channel form determined by the proposed method. In addition, a method for signaling the puncturing forms of the primary 160 MHz and the secondary 160 MHz in the 320 MHz BW configuration of the SU PPDU is proposed.

[0079] Also, in one embodiment of the present invention, a method is proposed to vary the configuration of the PPDU according to the preamble puncturing BW value indicated by the PPDU format signaled in the PPDU format field. Assuming that the length of the BW field is 4 bits, in the case of an EHT SU PPDU or a TB PPDU, since it is possible to further signal one symbol of EHT-SIG-A after U-SIG or not signal EHT-SIG-A at all, considering this, it is necessary to signal all up to 11 puncturing modes using only the BW field of U-SIG. However, in the case of an EHT MU PPDU, since EHT-SIG-B is further signaled after U-SIG, up to 11 puncturing modes may be signaled in a different way from the SU PPDU. In the case of an EHT ER PPDU, the BW field can be set to 1 bit to signal whether the PPDU uses a 20 MHz or 10 MHz bandwidth.

[0080] FIG. 7(f) shows the configuration of the format-specific field of the VD field when indicated as an EHT MU PPDU in the PPDU format field of U-SIG. In the case of a MU PPDU, SIG-B, which is a signaling field for simultaneous reception by multiple users, is essential, and SIG-B may be transmitted without a separate SIG-A after U-SIG. Therefore, U-SIG must signal information for decoding SIG-B. Such fields include the SIG-B MCS, SIG-B DCM, Number of SIG-B Symbols, SIG-B Compression, Number of EHT-LTF Symbols fields, etc.

[0081] FIG. 8 shows an example of various EHT (Extremely High Throughput) PPDU (Physical Protocol Data Unit) formats according to an embodiment of the present invention and a method for indicating the same.

[0082] Referring to FIG. 8, the PPDU may be composed of a preamble and a data part, and the format of one type of EHT PPDU may be distinguished by the U-SIG field included in the preamble. Specifically, based on the PPDU format field included in the U-SIG field, whether the format of the PPDU is an EHT PPDU may be indicated.

[0083] FIG. 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 an EHT-SIG-A field for additional signaling may be located after the U-SIG field.

[0084] FIG. 8(b) shows an example of the EHT trigger-based PPDU format, which is an EHT PPDU transmitted based on a trigger frame. The EHT trigger-based PPDU is an EHT PPDU transmitted based on a trigger frame and is an uplink PPDU used for responding to the trigger frame. Different from the EHT SU PPDU, the EHT-SIG-A field is not located after the U-SIG field in the EHT PPDU.

[0085] FIG. 8(c) shows an example of the EHT MU PPDU format, which is an EHT PPDU for multiple users. The EHT MU PPDU is a PPDU used to transmit the PPDU to one or more STAs. The EHT MU PPDU format may have an HE-SIG-B field located after the U-SIG field.

[0086] (d) of FIG. 8 shows an example of the EHT ER SU PPDU format used for single-user transmission with STAs in an extended range. The EHT ER SU PPDU may be used for single-user transmission with a wider range of STAs than the EHT SU PPDU described in (a) of FIG. 8, and the U-SIG field may be repeatedly positioned on the time axis.

[0087] The EHT MU PPDU described in (c) of FIG. 8 can be used by the AP for downlink transmission to multiple STAs. At this time, the EHT MU PPDU can include scheduling information so that multiple STAs can receive the PPDU transmitted from the AP simultaneously. The EHT MU PPDU can transmit the AID information of the recipient and / or transmitter of the PPDU to the STA through the user specific field of the EHT-SIG-B. Therefore, multiple terminals that receive the EHT MU PPDU can perform a spatial reuse operation 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 of the HE-SIG-B field included in the HE MU PPDU can include information regarding the configuration of resource units (e.g., the division form of resource units) in a specific bandwidth on the frequency axis (e.g., 20 MHz, etc.). That is, the RA field can indicate the configuration of resource units divided by the bandwidth for the transmission of the HE MU PPDU for the STA to receive the PPDU. The information of the STA assigned (or designated) to each divided resource unit may be included in the user specific field of the EHT-SIG-B and transmitted to the STA. That is, the user specific field can include one or more user fields corresponding to each divided resource unit.

[0089] For example, among a plurality of divided resource units, a user field corresponding to at least one resource unit used for data transmission can include the AID of the recipient or the sender, and a user field corresponding to the remaining resource units not used for data transmission can include a pre-set Null STA ID.

[0090] Two or more PPDUs shown in FIG. 8 can be indicated by a value indicating the same PPDU format. That is, two or more PPDUs can be indicated with the same PPDU format by the same value. For example, an EHT SU PPDU and an EHT MU PPDU can be indicated by the same value using a U-SIG PPDU format subfield. At this time, the EHT SU PPDU and the EHT MU PPDU can be distinguished by the number of STAs receiving the PPDU. For example, a PPDU received by only one STA can be identified as an EHT SU PPDU, and when the number of STAs is set so that two or more STAs receive it, it can be identified as an EHT MU PPDU. In other words, two or more PPDU formats shown in FIG. 8 can be indicated using the same subfield value.

[0091] Also, some of the fields shown in FIG. 8 or part of the information of the fields may be omitted, and the case where some of the fields or part of the information of the fields are omitted can be defined as a compression mode or a compressed mode.

[0092] FIG. 9 is a diagram showing a multi-link device according to an embodiment of the present invention.

[0093] Referring to FIG. 9, a concept of a device with one or more STAs affiliated may be defined. Further, as another example, according to one embodiment of the present invention, a device with more than one (i.e., two or more) STAs affiliated may be defined. At this time, the device may be a logical concept. Therefore, a device with one or more or more than one STA of such a concept can be called a multi-link device (MLD), a multi-band device, or a multi-link logical entity (MLLE).

[0094] Alternatively, the device of the above concept can be called a multi-link entity (MLE). Also, the MLD may have one MAC SAP (medium access control service access point) up to LLC (logical link control), and the MLD may have one MAC data service.

[0095] The STAs included in the MLD can operate on one or more links or channels. That is, the STAs included in the MLD can operate on a plurality of different channels from each other. For example, the STAs included in the MLD can operate using channels in different frequency bands of 2.4 GHz, 5 GHz, and 6 GHz. Thereby, the MLD can obtain a gain in channel access and improve the performance of the entire network. Existing wireless LANs operated on a single link, but MLD operation can obtain more channel access opportunities using a plurality of links, or the STAs can operate efficiently on a plurality of links considering the channel situation.

[0096] Also, when the STA affiliated with the MLD is an AP, the MLD affiliated with the AP may be an AP MLD. However, when the STA affiliated with the MLD is a non-AP STA, the MLD affiliated with the non-AP may be a non-AP MLD.

[0097] Also, an AP MLD (Multi-link Device) may be a device that includes one or more wireless access points (APs), and may be a device connected to the upper layer via one interface. That is, the AP MLD may be connected to the LLC (Logical Link Control) layer via one interface. The plurality of APs included in the AP MLD may share some functions at the MAC layer. Each AP within the AP MLD may operate on an individual link. A STA MLD may be a device that includes one or more non-AP STAs, and may be a device connected to the upper layer via one interface.

[0098] That is, the STA MLD may be connected to the LLC layer via one interface. The plurality of STAs included in the STA MLD may share some functions at the MAC layer. Also, the STA MLD can be called a non-AP MLD. At this time, the AP MLD and the STA MLD can perform a multi-link operation of communicating using a plurality of individual links. That is, when the AP MLD includes a plurality of APs, each AP constitutes a separate link and can perform frame transmission and reception operations using a plurality of links with each terminal included in the STA MLD. At this time, each link can operate in a band of 2.4 GHz, 5 GHz, or 6 GHz, and bandwidth expansion operations can be performed on each link. For example, when the AP MLD sets one link in the 2.4 GHz band and two links in the 5 GHz band, frame transmission can be performed with a bandwidth of 40 MHz using the bandwidth expansion method in the 2.4 GHz band, and frame transmission can be performed with a maximum bandwidth of 320 MHz using discontinuous bandwidths on each link using the 5 GHz band.

[0099] On the one hand, due to interference problems within the device, it may be that while one terminal in the MLD is performing a transmission operation, other terminals cannot perform a reception operation. When one AP or terminal in the MLD performs a transmission operation in this way, the operation of other APs or terminals in the MLD receiving during this process is called STR (Simultaneous Transmit and Receive). The AP MLD is capable of performing the STR operation for all links. Or, the STR operation is not possible for some links of the AP MLD. There may be a terminal MLD capable of performing the STR operation connected to the AP MLD, or an MLD that is not capable of performing the STR operation for some or all links may be connected. In addition, there may be a terminal (for example, an IEEE 802.11a / b / g / n / ac / ax terminal) that does not belong to the MLD further connected to the AP included in the AP MLD.

[0100] The AP MLD and the STA MLD can perform a negotiation process for the multi-link utilization operation in the scanning and connection process described in FIG. 5. For example, in the scanning process described in FIG. 5, the AP included in the AP MLD can transmit by including an indicator indicating that the multi-link operation is available, the number of available links, and information on a plurality of available links in the beacon frame. Or, a terminal belonging to the STA MLD can transmit by including an indicator indicating that the multi-link operation is available in the probe request frame, and the AP belonging to the AP MLD can include an indicator indicating that the multi-link operation is available in the probe response frame. At this time, the AP can further transmit by including the number of available links, link information, etc. during the multi-link operation.

[0101] Whether to perform the multi-link operation of AP MLD in the scanning process and the STA MLD that has confirmed the link information to be used can perform the connection process with AP MLD. At this time, AP MLD and STA MLD can start the negotiation process for the multi-link operation. At this time, the negotiation process for the multi-link operation may be performed in the connection process between the AP belonging to AP MLD and the terminal belonging to STA MLD. That is, while any terminal (for example, STA1) belonging to STA MLD sends a connection request frame to any AP (for example, AP1) belonging to AP MLD, an indicator indicating that the multi-link operation of the terminal is available and a request indicator requesting to perform the multi-link operation can be sent. The AP that has received the connection request frame from the terminal can confirm the indicator requesting the multi-link operation, and when the AP is capable of the multi-link operation, can send a connection response frame allowing the multi-link operation including the link information used for the multi-link operation and the parameters used for each link to the terminal. The parameters for the multi-link operation may include one or more of the bandwidth of each link used, the bandwidth expansion direction, TBTT (Target Beacon Transmission Time), and the presence or absence of the STR operation. After the connection process, AP MLD and STA MLD for which the use of the multi-link operation has been confirmed by the exchange of the connection request frame and the response frame can perform the frame transmission operation on a plurality of links via the plurality of APs included in AP MLD and the plurality of terminals included in STA MLD.

[0102] Referring to FIG. 9, there may be an MLD including a plurality of STAs, and the plurality of STAs included in the MLD may operate on a plurality of links. In FIG. 9, the MLD including APs AP1, AP2, and AP3 can be called AP MLD, and the MLD including non-AP STAs non-AP STA1, non-AP STA2, and non-AP STA3 can be called non-AP MLD. The STAs included in the MLD can operate on Link 1 (Link1), Link 2 (Link2), Link 3 (Link3), or some of Links 1 to 3.

[0103] According to an embodiment of the present invention, the multi-link operation may include a multi-link setup operation. The multi-link setup operation may be an operation corresponding to an association performed in a single-link operation. In order to exchange frames in a multi-link, a multi-link setup is required to precede. The multi-link setup operation may be performed using a multi-link setup element. Here, the multi-link setup element may include capability information related to the multi-link, and the capability information may include information regarding whether an STA included in the MLD can receive a frame on one link while another STA included in the MLD can transmit a frame on another link at the same time. That is, the capability information may include information regarding whether an STA (non-AP STA and / or AP (or, AP STA) included in the MLD can transmit / receive frames in different transmission directions simultaneously with each other through the links included in the MLD. Further, the capability information may further include information regarding available links or operating channels. The multi-link setup may be set by negotiation between peer STAs, and the multi-link operation may be set through one link.

[0104] According to an embodiment of the present invention, a mapping relationship may exist between a TID and a link of the MLD. For example, when a TID and a link are mapped, the TID may be transmitted on the mapped link. The mapping between the TID and the link may be made based on the transmission direction. For example, the mapping may be made for each direction in both directions between MLD1 and MLD2. Further, the mapping between the TID and the link may have a default setting. For example, the mapping between the TID and the link may basically be that all TIDs are mapped to a certain link.

[0105] FIG. 10 is a diagram showing an example of a TID-to-link mapping method according to an embodiment of the present invention.

[0106] Referring to FIG. 10, there may be a mapping relationship between the TID and the link as described in FIG. 9. Also, in the present invention, the mapping relationship between the TID and the link can be referred to as TID-to-link mapping, TID-to-link mapping, TID mapping, link mapping, etc. The TID may be a traffic identifier. Also, the TID may be an ID (identifier) for classifying traffic, data, etc. to support QoS (quality of service).

[0107] Also, the TID may be an ID used or assigned at a layer higher than the MAC layer. The TID can indicate TC (traffic categories) and TS (traffic streams). Also, the TID can have 16 values, for example, it may be indicated by values from 0 to 15. Also, individual TID values can be used according to the access policy or the channel connection and medium access method. For example, when using EDCA (HCF (hybrid coordination function)-based channel connection, extended distributed channel connection), the possible TID values may be 0 to 7. Also, when using EDCA, the TID value may indicate UP (user priority), and the UP may be related to TC or TS. Also, the UP may be a value assigned to a layer higher than the MAC. Also, when using HCCA (HCF controlled channel access) or SPCA, the possible TID values may be 8 to 15. Also, when using HCCA or SPCA, the TID may indicate TSID. Also, when using HEMM or SEMM, the possible TID values may be 8 to 15. Also, when using HEMM or SEMM, the TID may indicate TSID.

[0108] In addition, there may be a mapping relationship between the UP and the access category (AC). The AC may be a label for providing QoS in EDCA or a label indicating a set of EDCA parameters. The EDCA parameters or the set of EDCA parameters may be those used for channel concatenation. The AC may be used in a QoS STA.

[0109] The value of the AC may be set to one of AC_BK, AC_BE, AC_VI, and AC_VO. AC_BK, AC_BE, AC_VI, and AC_VO may respectively indicate background, best effort, video, and voice. In addition, it is possible to subdivide AC_BK, AC_BE, AC_VI, and AC_VO. For example, AC_VI may be subdivided into AC_VI primary and AC_VI alternate. Also, AC_VO may be subdivided into AC_VO primary and AC_VO alternate. Also, the UP value or the TID value may be mapped to the AC value. For example, the UP value or the TID values 1, 2, 0, 3, 4, 5, 6, 7 may be respectively mapped to AC_BK, AC_BK, AC_BE, AC_BE, AC_VI, AC_VI, AC_VO, AC_VO. Or, the UP value or the TID values 1, 2, 0, 3, 4, 5, 6, 7 may be respectively mapped to AC_BK, AC_BK, AC_BE, AC_BE, AC_VI alternate, AC_VI primary, AC_VO primary, AC_VO alternate. Also, the UP value or the TID values 1, 2, 0, 3, 4, 5, 6, 7 may be in order of higher priority. That is, 1 may have a lower priority and 7 may have a higher priority. Therefore, the priorities may increase in the order of AC_BK, AC_BE, AC_VI, AC_VO. Also, AC_BK, AC_BE, AC_VI, and AC_VO may respectively correspond to ACI (AC index) 0, 1, 2, 3.

[0110] Therefore, it is possible that there is a relationship between TID and AC. Therefore, the TID-to-link mapping of the present invention may be a mapping relationship between AC and a link. Further, in the present invention, the fact that a TID is mapped may mean that an AC is mapped, or vice versa.

[0111] According to an embodiment of the present invention, there may be a TID mapped to each link of multi-link. For example, there may be a mapping for which link among a plurality of links allows transmission and reception of a specific TID or a specific AC. Further, such a mapping may be defined individually for each direction of both directions of the link. Also, as described above, there may be a basic (default) setting for the mapping between TID and link. For example, basically, all TIDs may be mapped to a certain link. Further, according to an embodiment, at a specific time point, a certain TID or a certain AC may be mapped to at least one link. Also, a management frame or a control frame may be transmitted on all links.

[0112] In the present invention, a data frame corresponding to a TID or an AC mapped to any direction of a link may be transmitted. Also, a data frame corresponding to a TID or an AC not mapped to any direction of a link may not be transmitted.

[0113] According to an embodiment, the TID-to-link mapping may also be applied to an acknowledgment. For example, a block ack agreement may be based on the TID-to-link mapping. Or, the TID-to-link mapping may be based on a block ack agreement. For example, it is possible that there is a block ack agreement for a TID mapped by the TID-to-link mapping.

[0114] It is possible to provide QoS services by performing TID-to-link mapping. For example, by mapping a high-priority AC or TID to a link with good channel conditions or few STAs, it is possible to quickly transmit data for the AC or TID. Alternatively, by performing TID-to-link mapping, it is possible to help the STAs on a specific link save power (or enter the doze state).

[0115] Referring to FIG. 10, there may be an AP MLD including AP1 and AP2. Also, there may be a Non-AP MLD including STA1 and STA2. Also, there may be two links, Link1 and Link2, in the AP MLD. AP1 and STA1 may be associated via Link1, and AP2 and STA2 may be associated via Link2.

[0116] Therefore, Link1 may include a link for transmitting from AP1 to STA1 and / or a link for transmitting from STA1 to AP1, and Link2 may include a link for transmitting from AP2 to STA2 and / or a link for transmitting from STA2 to AP2. At this time, each link may have a TID and / or an AC mapped thereto.

[0117] For example, all TIDs and all ACs may be mapped to the link for transmitting from AP1 to STA1 on Link1 and the link for transmitting from STA1 to AP1 on Link1. Also, only AC_VO or the TIDs corresponding to AC_VO may be mapped to the link for transmitting from STA2 to AP2 on Link2. Also, only the data of the mapped TID and / or AC can be transmitted on the link. Also, the data of the TID or AC not mapped to the link cannot be transmitted on the link.

[0118] FIG. 11 is a diagram showing an example of a multi-link NAV setting operation according to an embodiment of the present invention.

[0119] The operation for the MLD to transmit or receive simultaneously (STR; simultaneous transmit and receive; simultaneous transmission and reception) may be restricted, which may be related to the frequency interval between a plurality of links operating in a multi-link.

[0120] Therefore, according to an embodiment of the present invention, when the interval between links is m MHz, it is restricted to transmit or receive simultaneously, and when the interval between links is n MHz for n greater than m, it may not be restricted to transmit or receive simultaneously. This embodiment may be for solving the problem that it is restricted to transmit or receive simultaneously, and duplicate descriptions may be omitted. Further, this embodiment can be applied to an MLD that does not support STR.

[0121] According to an embodiment of the present invention, duration information may be shared between links operating as a multi-link. As an example, the duration information may be TXOP duration information transmitted in a signaling field of a preamble. The signaling field may be the U-SIG field described above. Alternatively, the signaling field may be the HE-SIG-A field described above. As yet another example, the duration information may be the duration information indicated by a Duration / ID field included in a MAC header. As yet another example, the duration information may be the duration information indicated by a Length field (L Length field) included in an L-SIG field. According to an embodiment, the duration information indicated by the U-SIG field or HE-SIG-A or Duration / ID field may be a value indicating a TXOP duration. According to an embodiment, the duration information indicated by the L-SIG field may be the length of a PPDU (physical layer protocol data unit) including the L-SIG field or a value indicating the end of the PPDU including the L-SIG field.

[0122] Also, according to an embodiment of the present invention, it is possible to restrict transmission or channel connection during a period based on period information shared between links. A method of restricting transmission or channel connection may include setting a NAV. Alternatively, the NAV can be reset to resume transmission or channel connection. At this time, the NAV may be an intra-BSS NAV. The intra-BSS NAV may be a NAV set by an intra-BSS frame (or, PPDU). That is, a STA belonging to an MLD can set a NAV based on a frame (or, PPDU) directed to another STA belonging to the MLD.

[0123] According to an embodiment of the present invention, an inter-link NAV may exist. The inter-link NAV may be a NAV used by STAs of a plurality of links belonging to a certain MLD when operating in a multi-link. For example, transmission on link 2 may not be necessary based on an inter-link NAV set based on period information received on link 1. Also, the inter-link NAV can exist or be used for an MLD that is not STR-capable. For example, when an inter-link NAV is set, the MLD that set the inter-link NAV does not have to perform transmission or channel connection on a plurality of links (or, all links used by the MLD).

[0124] Also, in addition to the intra-BSS NAV, a basic NAV may exist as a type of NAV. The basic NAV may be a NAV set by an inter-BSS frame (or, PPDU), and the basic NAV may also be set by a frame (or, PPDU) for which it is not determined whether it is intra-BSS or inter-BSS.

[0125] When using the inter-link NAV separately, it may have advantages in situations where the NAV settings are updated compared to when not using the inter-link NAV. For example, a situation may occur where it is possible to reset the NAV set by other links. For example, although the inter-link NAV is set based on a certain frame (or PPDU), it may be determined that the frame (or PPDU) is not directed to the same MLD, and it may be acceptable to reset the set inter-link NAV. Suppose there is an MLD operating on Link 1 and Link 2. The NAV for Link 1 may be set based on the frame received on Link 1. Subsequently, the NAV for Link 1 may be updated based on the frame of Link 2. And when it is no longer necessary to maintain the NAV by Link 2, if the NAV of Link 1 is reset, there is a problem of losing the NAV information set based on the frame received on Link 1. If the inter-link NAV is used together with the NAV for each link, even if the inter-link NAV is reset, the NAV for each link is maintained, and the above problem can be solved.

[0126] Although the setting of the NAV has been taken up in the embodiments of the present invention, the embodiments of the present invention are not limited thereto and are also applicable to instructing to interrupt the channel connection at the physical layer or instructing that the channel state is busy. Also, it is not limited to resetting the NAV, and it is also applicable to instructing to continue the channel connection at the physical layer or instructing that the channel state is idle. At this time, primitives exchanged between the physical layer and the MAC layer may be used. Or, primitives exchanged between one STA of the MLD and other STAs may be used. Or, primitives exchanged between one MAC layer of the MLD and other MAC layers may be used.

[0127] According to an embodiment of the present invention, when a STA belonging to an MLD starts receiving a PPDU, other STAs belonging to the MLD may have to stop channel connection. As described above, the channel connection may be stopped based on the received period information. However, due to the position of the field including the period information or the time required for decoding or the like, there may be a time from when the PPDU starts to be received until the period information is obtained. Therefore, accessing the channel and starting transmission during this time may lead to the above-mentioned problem. For this reason, according to an embodiment of the present invention, a STA of an MLD can interrupt the channel connection from the time when other STAs of the MLD start receiving. Also, when it is confirmed that the frame received after other STAs of the MLD start receiving is not directed to the other STAs, the channel connection can be started again.

[0128] FIG. 12 is a diagram showing still another example of a multi-link NAV setting operation according to an embodiment of the present invention.

[0129] FIG. 12 is a specific implementation of the method described in the embodiment illustrated in FIG. 11, and redundant descriptions may be omitted.

[0130] As described above, based on the frame or PPDU received by a certain STA belonging to the MLD, other STAs belonging to the same MLD can suspend or resume channel connection or transmission. In the present invention, suspending channel connection or transmission may include operations such as setting (updating) the NAV, determining that the channel is busy, or suspending the CCA. Further, resuming channel connection or transmission may include operations such as resetting the NAV, canceling the NAV setting, determining that the channel is idle, or performing the CCA. In the following, such operations can be instructed as suspending and resuming the channel connection. Further, hereinafter, it can be described that STA1 and STA2 belong to the MLD, and STA1 and STA2 operate on Link1 and Link2, respectively. Further, the frame and the PPDU can be interchangeably instructed. Further, the NAV at this time may be the intra-BSS NAV or the inter-link NAV as described in FIG. 11.

[0131] According to an embodiment of the present invention, when STA1 starts receiving a frame, STA2 may interrupt the channel connection. Further, when STA1 obtains the duration information from the L-SIG, STA2 may maintain the state of interrupting the channel connection. At this time, the state in which STA2 interrupts the channel connection can be determined until the end of the frame received by STA1. Further, when STA1 cannot surely decode the L-SIG (when it is an invalid L-SIG), STA2 can resume the channel connection.

[0132] In addition, STA1 can receive TXOP duration and BSS color from the U-SIG of the frame it receives. If the received BSS color indicates that it is intra-BSS or the BSS color corresponds to the BSS color of STA1, the channel connection can be interrupted. As an example, the period for interrupting the channel connection at this time may be until the end of the received frame. In this case, after the received frame ends, there is an advantage that the channel connection can be started earlier. As another example, the period for interrupting the channel connection at this time may be the TXOP duration. In this case, the period of the channel connection interrupted based on the L-SIG may be updated. In this case, there is an advantage that the sequence following the received frame can be better protected.

[0133] Alternatively, STA1 may receive TXOP duration and BSS color from the U-SIG of the frame it receives, and the received BSS color may not indicate intra-BSS or may not correspond to the BSS color of STA1. Or, there may be a case where STA1 fails to successfully decode the U-SIG. In such a case, STA2 can resume the channel connection.

[0134] Or, when the information obtained by STA1 from the U-SIG of the received frame indicates that the frame is a frame that STA1 does not receive, STA2 can resume the channel connection. For example, when the PHY identifier obtained from the U-SIG is an ID corresponding to a future standard or an unrecognizable ID, STA2 can resume the channel connection.

[0135] Also, although the case of receiving the U-SIG has been described, the same example can also be applied when receiving the HE PPDU or when receiving the HE-SIG-A. For example, the HE-SIG-A may include the TXOP duration and the BSS color, and thus, the operations as described above can be performed.

[0136] In addition, STA1 may receive a STA-ID from the EHT-SIG of the frame it receives. If the received STA-ID is an indicator that STA1 should receive, for example, when the STA-ID indicates STA1, indicates the group to which STA1 belongs, or indicates broadcast, STA2 can maintain the state of interrupting the channel connection.

[0137] Alternatively, STA1 may receive a STA-ID from the EHT-SIG of the frame it receives. If the received STA-ID is an indicator that does not correspond to STA1, for example, when the STA-ID does not indicate an indicator corresponding to STA1, does not indicate the group to which STA1 belongs, or does not indicate broadcast, STA2 can resume the channel connection. Or, STA2 can also resume the channel connection when STA1 fails to successfully decode the EHT-SIG.

[0138] In addition, although the case of receiving the EHT-SIG has been described, this embodiment can also be applied when receiving an HE PPDU or when receiving an HE-SIG-B. For example, the HE-SIG-B may include a STA-ID, and thus, the operations as described above can be performed.

[0139] In addition, STA1 may receive the MAC header of the frame it receives. If the RA (receiver address) or DA (destination address) included in the received MAC header indicates the value that STA1 should receive, for example, when the RA or DA indicates STA1, indicates the group to which STA1 belongs, or indicates broadcast, STA2 can maintain the state of interrupting the channel connection. At this time, the period of interrupted channel access can be obtained based on the period information included in the received MAC header. More specifically, the period of interrupted channel access can be obtained based on the period information indicated by the Duration / ID field included in the received MAC header.

[0140] Also, STA1 may be receiving the MAC header of the frame it receives. If the RA or DA included in the received MAC header is an indicator that does not correspond to STA1, for example, if the RA or DA does not indicate an indicator corresponding to STA1, does not indicate the group to which STA1 belongs, or does not indicate broadcast, STA2 can resume the channel connection. Or, STA1 may not be receiving all MAC headers. For example, STA1 may fail to receive all MPDUs included in an A-MPDU. In this case, STA2 can resume the channel connection.

[0141] The channel connection interruption and resumption described in FIG. 12 may operate in the order of decoding as the frame (or PPDU) is received by STA1 and sequentially decoded. The decoding order may be based on the PPDU format, frame format, etc. For example, it can be decoded in the order of L-SIG, U-SIG, EHT-SIG, MAC header (in the case of EHT PPDU). Or, it can be decoded in the order of L-SIG, HE-SIG-A, MAC header (in the case of HE SU PPDU, HE TB PPDU). Or, it can be decoded in the order of L-SIG, HE-SIG-A, HE-SIG-B, MAC header (in the case of HE MU PPDU). Or, it can be decoded in the order of L-SIG, MAC header (in the case of 11a / g PPDU).

[0142] According to an embodiment of the present invention, the aforementioned STA-ID may be a value indicating the intended receiver of the PPDU or RU (resource unit). Also, the STA-ID may be included in the EHT-SIG field or HE-SIG-B field, etc. Also, the STA-ID can indicate a value corresponding to a single STA. For example, when multiple STAs are included in an MLD, the STA-ID can indicate a value corresponding to one of the multiple STAs. Also, the STA-ID may be a value based on the AID or MAC address of the STA.

[0143] FIG. 13 is a diagram showing an example of BSS classification according to an embodiment of the present invention and operations based thereon.

[0144] According to an embodiment of the present invention, a STA can classify (or determine) a BSS based on a received frame or a received PPDU. Classifying a BSS may include an operation of classifying whether a received frame or a received PPDU corresponds to a BSS to which the STA belongs. Or, classifying a BSS may mean an operation of classifying whether a received frame or a received PPDU is transmitted from a BSS to which the STA belongs. Also, classifying a BSS may include an operation of classifying whether a received frame or a received PPDU corresponds to a BSS to which the STA does not belong. Or, classifying a BSS may mean an operation of classifying whether a received frame or a received PPDU is transmitted from a BSS to which the STA does not belong. Also, classifying a BSS may include an operation of classifying to which BSS a received frame or a received PPDU belongs. Or, classifying a BSS may mean an operation of classifying from which BSS a received frame or a received PPDU is transmitted. According to an embodiment of the present invention, the BSS to which the STA to be classified belongs can be called an intra-BSS. Or, a BSS including the BSS to which the STA to be classified belongs can be called an intra-BSS. Also, a BSS that is not an intra-BSS can be called an inter-BSS. Or, a BSS that is not an intra-BSS may be an inter-BSS or a BSS that is not classified. Or, an inter-BSS may include a BSS that is not classified. Also, a BSS to which the STA to be classified does not belong can be called an inter-BSS.

[0145] According to one embodiment, when it is determined that the received frame or the received PPDU belongs to an intra-BSS or is transmitted from an intra-BSS, the received frame or the received PPDU can be referred to as an intra-BSS frame and an intra-BSS PPDU, respectively. Also, when it is determined that the received frame or the received PPDU belongs to an inter-BSS or is transmitted from an inter-BSS, the received frame or the received PPDU can be referred to as an inter-BSS frame and an inter-BSS PPDU, respectively. Also, a PPDU including an intra-BSS frame may be an intra-BSS PPDU. Also, a PPDU including an inter-BSS frame may be an inter-BSS PPDU.

[0146] According to one embodiment of the present invention, a BSS can be classified based on one or more BSS classification conditions. For example, a BSS can be classified according to whether or not at least one of the one or more BSS classification conditions is satisfied.

[0147] The BSS classification condition may include a condition based on the BSS color. The BSS color may be an identifier for the BSS. Also, the BSS color may be included in the preamble of the PPDU, more specifically, in the signaling field (e.g., the HE-SIG-A field or the U-SIG field or the VHT-SIG-A field). Also, the BSS color may be included in the TXVECTOR transmitted from the MAC layer of the sender to the PHY layer. Also, the BSS color may be included in the RXVECTOR transmitted from the PHY layer of the receiver to the MAC layer. The parameters included in the TXVECTOR and the RXVECTOR can be called TXVECTOR parameters and RXVECTOR parameters, respectively. Also, the BSS color may be included in the TXVECTOR parameters or the RXVECTOR parameters. Also, the AP can notify the STA of the BSS color set by the AP. According to one embodiment, the BSS can be classified based on the BSS color included in the received PPDU. If the BSS color included in the PPDU received by the STA is different from the BSS color of the BSS corresponding to the STA, the received PPDU can be classified as an inter-BSS PPDU. Or, if the BSS color included in the PPDU received by the STA is different from the BSS color of the BSS corresponding to the STA and its value is not 0, the received PPDU can be classified as an inter-BSS PPDU. Also, if the BSS color included in the PPDU received by the STA is the same as the BSS color of the BSS corresponding to the STA, the received PPDU can be classified as an intra-BSS PPDU.

[0148] The BSS classification condition may include a condition based on the MAC address. The MAC address may be included in the MAC header of the frame. Also, the MAC address may include the RA (receiver address), TA (transmitter address), BSSID, SA (source address), DA (destination address), etc. According to one embodiment, the BSS can be classified based on the MAC address included in the received frame. If the MAC address included in the received frame is different from the BSSID of the BSS corresponding to the STA, the received frame can be classified as an inter-BSS frame. More specifically, if all the MAC addresses included in the received frame are different from the BSSID of the BSS corresponding to the STA, the received frame can be classified as an inter-BSS frame. Also, if the MAC address included in the received frame is the same as the BSSID of the BSS corresponding to the STA, the received frame can be classified as an intra-BSS frame. More specifically, if at least one of the MAC addresses included in the received frame is the same as the BSSID of the BSS corresponding to the STA, the received frame can be classified as an intra-BSS frame.

[0149] The corresponding BSS may include the BSS with which the STA is associated. Also, the corresponding BSS may include the BSS included in the same multiple BSSID set as the BSS with which the STA is associated. Also, the corresponding BSS may include the BSS included in the same co-hosted BSSID set as the BSS with which the STA is associated. Also, information regarding the one or more BSSs included in the same multiple BSSID set or the same co-hosted BSSID set may be transmitted through one frame to the one or more BSSs.

[0150] The BSS classification condition may include a condition based on the Partial AID field value included in the VHT PPDU. The Partial AID field may be included in the preamble of the VHT PPDU. Also, the Partial AID field may be included in the VHT-SIG-A field included in the VHT PPDU. According to one embodiment, the Partial AID field can indicate a part of the BSS color. For example, when using the partial BSS color function, the Partial AID field can indicate a part of the BSS color. Or, when using an AID assignment rule, the Partial AID field can indicate a part of the BSS color. The AID assignment rule may be a method of assigning an AID based on the BSS color. Also, when the Group ID field included in the VHT-SIG-A field of the VHT PPDU is a preset value (for example, when the Group ID field is set to 63), the Partial AID field can indicate a part of the BSS color. According to one embodiment, when the Partial AID field of the received PPDU indicates a part of the BSS color, if the received Partial AID field value is different from the part of the BSS color corresponding to the received STA, the received PPDU can be classified as an inter-BSS PPDU.

[0151] Also, when the Partial AID field of the received PPDU indicates a part of the BSS color, if the received Partial AID field value is the same as a part of the BSS color corresponding to the received STA, the received PPDU can be classified as an intra-BSS PPDU. At this time, a part of the BSS color can be the 4 LSBs of the BSS color. According to another embodiment, the Partial AID field can indicate a part of the BSSID. For example, when the Group ID field included in the VHT-SIG-A field of the VHT PPDU is a set value (for example, when the Group ID field is set to 0), the Partial AID field can indicate a part of the BSSID. According to one embodiment, when the Partial AID field of the received PPDU indicates a part of the BSSID, if the received Partial AID field value is different from a part of the BSSID corresponding to the received STA, the received PPDU can be classified as an inter-BSS PPDU. Also, when the Partial AID field of the received PPDU indicates a part of the BSSID, if the received Partial AID field value is the same as a part of the BSSID corresponding to the received STA, the received PPDU can be classified as an intra-BSS PPDU. At this time, a part of the BSSID can be the 9 MSBs of the BSSID. Also, the Partial AID field value may be included in the TXVECTOR parameter PARTIAL_AID or the RXVECTOR parameter PARTIAL_AID. Also, the Group ID field value may be included in the TXVECTOR parameter GROUP_ID or the RXVECTOR parameter GROUP_ID.

[0152] The BSS classification conditions may include the condition that the AP receives a PPDU of the already set conditions. For example, the PPDU of the already set conditions may include a downlink PPDU. According to one embodiment, the downlink PPDU may include a VHT MU PPDU. Also, the downlink PPDU may include a PPDU in which the signaling indicating whether it is an uplink or a downlink is set to the already set value. The signaling indicating whether it is an uplink or a downlink may be included in the signaling field of the HE PPDU. Or, the signaling indicating whether it is an uplink or a downlink may be included in the U-SIG. The U-SIG may be included in the preamble of the EHT PPDU or a PPDU after the EHT standard.

[0153] Also, there may be cases where it cannot be classified into an intra-BSS PPDU or an inter-BSS PPDU. For example, when neither the conditions for classifying into the aforementioned intra-BSS PPDU nor the conditions for classifying into the inter-BSS PPDU can be satisfied, it cannot be classified into an intra-BSS PPDU or an inter-BSS PPDU.

[0154] Also, when classifying the BSS, if the classification results based on multiple conditions do not match, it is possible to determine the final result according to the already set conditions. For example, when the result based on the condition based on the BSS color and the result based on the condition based on the MAC address do not match, the result based on the condition based on the MAC address may be prioritized, or the result based on the condition based on the MAC address may be determined as the final result. Or, when both the conditions for classifying into the intra-BSS PPDU and the conditions for classifying into the inter-BSS PPDU are satisfied, it can be classified into the intra-BSS PPDU.

[0155] According to an embodiment of the present invention, the STA can perform operations based on the classified BSS. The operations based on the classified BSS may include intra-PPDU power save operations. The intra-PPDU power save operation may be a power save operation based on the received PPDU. It is possible to perform the intra-PPDU power save operation when the already set conditions are satisfied. The already set conditions may include the conditions for classifying the received PPDU as an intra-BSS PPDU. Also, the already set conditions may include the condition that the intended receiver of the received PPDU is not the STA that received the PPDU. For example, when the ID or address included in the PPDU does not correspond to the STA that received the PPDU, the intended receiver of the PPDU may not be the STA that received the PPDU. The ID may be included in the preamble of the PPDU. For example, the ID may be the STA_ID included in the preamble of the PPDU. Also, the STA_ID may be included in the HE MU PPDU or the EHT PPDU. Also, the address may be the MAC address described above. Also, when the signaling indicating whether the received PPDU is an uplink or a downlink indicates an uplink, the intended receiver of the PPDU may not be the STA that received the PPDU. Also, when the setting of the received PPDU is set to something that the STA that received the PPDU does not support, the intended receiver of the PPDU may not be the STA that received the PPDU. The setting of the received PPDU may include the MCS of the PPDU, the number of spatial streams, the channel width, etc. Also, when the setting of the received PPDU is not supported by the STA that received the PPDU, the PHY-RXEND.indication(UnsupportedRate) primitive may be received. Also, when the received PPDU is in the already set format, the intended receiver of the PPDU may not be the STA that received the PPDU. The already set format may include the TB PPDU.The TB PPDU may include the HE TB PPDU and the EHT TB PPDU. Also, the TB PPDU may be a PPDU transmitted as a response to a triggering frame. The triggering frame may include a trigger frame. The triggering frame may include a frame containing triggering information. The triggering information may be included in the MAC header, for example, the A-control field. Also, the information included in the triggering information or the trigger frame may include the length of the responding PPDU, the RU used during response, the PHY configuration used during response, the MAC configuration, etc. The intra-PPDU power saving operation may be an operation that can enter the doze state until the end of the received PPDU. As yet another example, when it is determined that the intended recipient of the PPDU or frame received by the STA is not the STA, the reception or decoding of the PPDU or frame can be interrupted.

[0156] Operations based on the classified BSS may include the operation of setting (or updating) the NAV. According to one embodiment, a STA can operate one or more NAVs. Also, when a STA receives a PPDU or a frame, it is possible to set the NAV corresponding to the BSS classified based on the received PPDU or the received frame. For example, the intra-BSS NAV may be the NAV corresponding to the intra-BSS PPDU. Also, the basic NAV may be the NAV corresponding to a PPDU that is not an intra-BSS PPDU. Or, the basic NAV may be the NAV corresponding to an inter-BSS PPDU. Also, when setting the NAV based on the received PPDU or the received frame, it is possible to use the duration information included in the received PPDU or the received frame. The duration information may include a TXOP. The TXOP can mean the value included in the TXOP field. The TXOP field may be included in the preamble of the PPDU. For example, the TXOP field may be included in the HE-SIG-A field of the HE PPDU. Or, the TXOP field may be included in the U-SIG field of the EHT PPDU or a PPDU of a standard after EHT. Also, the duration information may be included in the MAC header. For example, the duration information may be included in the Duration / ID field included in the MAC header.

[0157] Operations based on the classified BSS may include spatial reuse operations. Also, operations based on the classified BSS may include channel connection operations. The spatial reuse operation may be a channel connection operation. When a STA receives a PPDU or a frame, if the already set conditions are satisfied, it is possible to perform a spatial reuse operation. The already set conditions may include the condition that the received PPDU or the received frame corresponds to an inter-BSS. Also, the already set conditions may include the condition that the signal strength of the received PPDU or the received frame is smaller than a threshold. For example, the threshold may be variable. Also, the threshold may be a threshold for OBSS PD-based Spatial reuse operation. Also, the threshold may be a value equal to or greater than the CCA threshold. Also, the threshold may be a value based on the power to be transmitted. The spatial reuse operation may include the operation of transmitting a PPDU. Also, the spatial reuse operation may include the operation of resetting the PHY. For example, the operation of resetting the PHY may be the operation of issuing a PHY-CCARESET.request primitive. Also, the spatial reuse operation may include the operation of not setting the NAV based on the received PPDU or the received frame. If the STA performs a spatial reuse operation, it is possible for the STA to transmit a PPDU while the received PPDU or the received frame is being transmitted or received.

[0158] Referring to FIG. 13, BSS A and BSS B may exist, and BSS A and BSS B may be different BSSs from each other. Also, BSS A and BSS B may correspond to inter-BSS with each other. That is, a PPDU or frame transmitted by a STA associated with BSS B in BSS A may be classified as an inter-BSS PPDU or an inter-BSS frame. Also, there may be STAs STA1 and STA2 belonging to (or associated with an AP operating BSS A). There may be STAs STA3 and STA4 belonging to (or associated with an AP operating BSS B). Referring to FIG. 13, STA1 can transmit a PPDU. Also, the PPDU transmitted by STA1 may include information about the BSS. For example, the information about the BSS may be information for classifying the BSS described above. Also, the PPDU transmitted by STA1 may include Duration information.

[0159] STA2 can receive the PPDU transmitted by STA1 and classify the BSS for this PPDU. Also, since STA2 and STA1 belong to BSS A, the PPDU received by STA2 may be classified as an intra-BSS PPDU. Also, the PPDU received by STA2 may be an UL PPDU or a PPDU that is not the intended recipient of the STA. Therefore, according to the above-described embodiment, STA2 can perform intra-PPDU power saving. Referring to FIG. 13, STA2 can enter the doze state until the time at the end of the received PPDU. Also, STA2 can set the NAV based on the Duration information included in the received PPDU. Since STA2 classifies the received PPDU as an intra-BSS PPDU, it is possible to set the intra-BSS NAV.

[0160] STA3 can receive the PPDU transmitted by STA1 and classify the BSS for this PPDU. Also, since STA3 and STA1 belong to BSS B and BSS A respectively, the PPDU received by STA3 may be classified as an inter-BSS PPDU. Also, STA3 can set the NAV based on the Duration information included in the received PPDU. Since STA3 classifies the received PPDU as an inter-BSS PPDU, it is possible to set the basic NAV.

[0161] STA4 can receive the PPDU transmitted by STA1 and classify the BSS for this PPDU. Also, since STA4 and STA1 belong to BSS B and BSS A respectively, the PPDU received by STA4 may be classified as an inter-BSS PPDU. Also, the signal strength of the PPDU received by STA4 may be less than the threshold value. Therefore, since the PPDU received by STA4 is classified as an inter-BSS PPDU and the signal strength of the PPDU received by STA4 is less than the threshold value, STA4 can perform a spatial reuse operation. Therefore, STA4 can perform a channel connection and a backoff procedure and start transmission. For example, it is possible for STA4 to start transmission when the PPDU transmitted by STA1 has not ended.

[0162] FIG. 14 shows the functions of the STA according to the embodiment of the present invention.

[0163] According to an embodiment of the present invention, a STA compliant with a certain wireless LAN standard may include functions of a previous wireless LAN standard. This is for backward compatibility. For example, a STA that supports a specific wireless LAN standard can support the functions of a previous generation of wireless LAN standards and can further support new functions. For example, an HT STA can support the basic functions of an OFDM PHY STA. Therefore, an HT STA may be classified as an OFDM PHY STA. In addition to the functions of an OFDM PHY STA, an HT STA can also support additional functions that an OFDM PHY STA does not support. A VHT STA can support the basic functions of an HT STA and can also support functions that an HT STA does not support. A VHT STA may be classified as an HT STA. In addition to the basic functions of a VHT STA, an HE STA can also support functions that a VHT STA does not support. An HE STA may be classified as a VHT STA. Also, an EHT STA may be an HE STA. In addition to the basic functions of an HE STA, an EHT STA can also support functions that an HE STA does not support. Also, an EHT STA may be classified as an HE STA. Also, a wireless LAN standard after the EHT standard may be newly defined. In the present invention, a standard after the EHT standard is called a NEXT standard, and a STA compliant with the NEXT standard is called a NEXT STA. A NEXT STA can support the basic functions of an EHT STA and can also support functions that an EHT STA does not support. A NEXT STA may be classified as an EHT STA.

[0164] FIG. 14 is a diagram showing the relationship between STAs that support each wireless LAN standard. Referring to FIG. 14, an EHT STA may be an HE STA, a VHT STA, an HT STA, or an OFDM PHY STA. Also, a NEXT STA may be an EHT STA, an HE STA, a VHT STA, an HT STA, or an OFDM PHY STA.

[0165] FIG. 15 shows an uplink (UL) multi-user (MU) operation according to an embodiment of the present invention.

[0166] In one embodiment of the present invention, an access point can transmit a frame that solicits multi-user (MU) transmission. Such a frame is called a triggering frame. At this time, one or more STAs that receive the triggering frame can perform uplink transmission based on the triggering frame. Specifically, one or more STAs that receive the triggering frame can transmit a response frame to the frame. At this time, the inter-space between the PPDU including the triggering frame and the PPDU used for uplink transmission may be SIFS. Specifically, a plurality of STAs can receive the triggering frame and simultaneously transmit an immediate response. The immediate response indicates that the interval between the previously received PPDU and the PPDU including the response is SIFS.

[0167] The triggering frame may be a type of control frame and may be a trigger frame including trigger information. Also, the triggering frame may be a frame including trigger information in the MAC header. At this time, the trigger information may be TRS (triggered response scheduling) included in the HT Control field, Control subfield, or A-Control subfield of the MAC header. Also, the trigger information may be information that solicits the transmission of a TB PPDU.

[0168] The TB PPDU is a PPDU format that includes a response frame for a triggering frame. The TB PPDU may include a HE TB PPDU and an EHT TB PPDU. Also, the TB PPDU may include a NEXT TB PPDU defined by the NEXT wireless LAN standard. The HE TB PPDU includes a preamble that sequentially includes L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG-A, HE-STF, HE-LTF, and may include data and a packet extension (PE) following the preamble. Also, the EHT TB PPDU and NEXT TB PPDU include a preamble that sequentially includes L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, (EHT- / NEXT-)STF, (EHT- / NEXT-)LTF, and may include data and a packet extension (PE) following the preamble.

[0169] The triggering frame may include information necessary for TB PPDU transmission. When the value of the Type subfield (B3B2) of the MAC frame is 01 b and the value of the Subtype subfield (B7 B6 B5 B4) is 0010 b it may indicate that the MAC frame is a trigger frame.

[0170] When multiple STAs responding to a trigger frame transmit TB PPDUs in different formats, it may be difficult for the access point to receive the TB PPDUs. Also, when the preambles of the PPDUs transmitted by multiple STAs are different from each other, it may be difficult for the access point to receive the TB PPDUs. In particular, when the RUs in which TB PPDUs of different formats are transmitted overlap, it may be difficult for the access point to receive the TB PPDUs. Therefore, multiple STAs transmitting responses to one triggering frame can use TB PPDUs of the same format. Also, the preamble information of the TB PPDUs transmitted by multiple STAs transmitting responses to one triggering frame may be the same.

[0171] As described with reference to FIG. 14, a HE STA can transmit a HE TB PPDU. Also, an EHT STA can transmit an EHT TB PPDU or a HE TB PPDU. Also, a NEXT STA can transmit a NEXT TB PPDU, an EHT TB PPDU, or a HE TB PPDU.

[0172] In the embodiment of FIG. 15, the AP transmits a trigger frame that schedules the transmissions of the HE STA (HE STA) and the EHT STA (EHT STA). At this time, when the trigger frame does not indicate the format of the TB PPDU transmitted in response to the trigger frame, the HE STA (HE STA) and the EHT STA (EHT STA) or different EHT STAs (EHT STAs) from each other may transmit TB PPDUs in different formats. For this reason, the transmission of the TB PPDU may fail and the transmission opportunity may be wasted. For the sake of convenience of explanation, the trigger frames defined in the HE, EHT, and NEXT standards are referred to as HE trigger frames, EHT trigger frames, and NEXT trigger frames, respectively. Also, the TRSs defined in the HE, EHT, and NEXT standards are referred to as HE TRS, EHT TRS, and NEXT TRS. The format of the trigger frame will be described with reference to FIG. 16.

[0173] FIG. 16 shows the format of the trigger frame according to an embodiment of the present invention and the subfields included in the trigger frame.

[0174] Specifically, FIG. 16(a) shows the format of the trigger frame, FIG. 16(b) shows the Common Info field of the trigger frame, and FIG. 16(c) shows the User Info field of the trigger frame. The MAC header of the trigger frame includes a Frame Control field, a Duration field, and an Address field. At this time, the Address field includes an RA field and a TA field. Also, the trigger frame includes a Common Info field and a User Info List field. The Common Info field includes information for all stations triggered by the trigger frame. Also, the User Info List field may include a User Info field. In a specific embodiment, a specific type of trigger frame may not include a User Info List field. Also, the trigger frame may include a Padding field and an FCS field. The Padding field can play a role in increasing the frame length to ensure the time required for the STA receiving the trigger frame to prepare a response, and may optionally exist.

[0175] The Common Info field may include a Trigger Type subfield. The Trigger Type subfield identifies the trigger frame variant. The trigger frame can indicate the type of the trigger frame with the value of the Trigger Type subfield. Also, the information included in the Trigger Dependent Common Info subfield, the Trigger Dependent User Info subfield, and the lengths of the Trigger Dependent Common Info subfield and the Trigger Dependent User Info subfield may be determined by the Trigger Type subfield. For example, the Trigger Type subfield can be indicated by bits B0 to B3 of the Common Info field.

[0176] Also, the Common Info field may include a UL Length subfield. The UL Length subfield may include information regarding the length of the TB PPDU that responds to the Trigger frame. Alternatively, the UL Length subfield may include information regarding the length of the frame that responds to the Trigger frame. Also, the UL Length subfield may indicate the value included in the Length subfield of the L-SIG of the TB PPDU that responds to the Trigger frame. Therefore, the STA that responds with a TB PPDU can set the Length subfield of the L-SIG of the TB PPDU based on the value of the UL Length subfield included in the received Trigger frame. More specifically, the STA that responds with a TB PPDU can set the Length subfield of the L-SIG of the TB PPDU with the value of the UL Length subfield included in the received Trigger frame. For example, the UL Length subfield can be indicated by bits B4 to B15 of the Common Info field.

[0177] Also, the Common Info field may include a UL BW subfield. The UL BW subfield can indicate the bandwidth (BW) value included in the signaling field of the TB PPDU that responds to the trigger frame, for example, the HE-SIG-A field or the U-SIG field. Also, the UL BW subfield can indicate the maximum bandwidth of the TB PPDU that responds to the Trigger frame.

[0178] Also, the Common Info field may include information such as that included in the signaling field of the TB PPDU that responds to the trigger frame, for example, the HE-SIG-A field or the U-SIG field.

[0179] The User Info field may include the AID12 subfield. The AID12 subfield can serve to indicate the intended recipient of the User Info field that includes the AID12 subfield or the function of the User Info field. Thus, the AID12 subfield can serve to indicate the intended recipient of the trigger frame that includes the AID12 subfield or the function of the trigger frame. For example, when the value of the AID12 subfield is a preset value, the User Info field can indicate that it is an instruction for an RA-RU (random access resource unit). More specifically, when the value of the AID12 subfield is 0, the User Info field can indicate an RA-RU for an associated STA. Also, when the value of the AID12 subfield is 2045, the User Info field can indicate an RA-RU for an unassociated STA. Also, the User Info field or the trigger frame that includes the AID12 subfield and includes the STAID indicated by the value of the AID12 subfield, for example, an AID (association ID), can indicate that it triggers a response. For example, the AID12 subfield can indicate an AID or the 12 LSBs of an AID. The STA corresponding to the value of the AID12 subfield can respond to the trigger frame with a TB PPDU. Also, the value of the AID12 subfield may be in the range from 1 to 2007 (including 1 and 2007). Also, when the AID12 subfield has a preset value, for example, 2046, it can indicate that the corresponding RU is not assigned to any STA. Also, when the AID12 subfield has a preset value, for example, 4095, it can indicate the start of padding of the trigger frame.

[0180] Also, the information in the User Info field including the AID12 subfield may be information corresponding to the STA indicated by the AID12 subfield. For example, the RU Allocation subfield can indicate the size and location of the RU. At this time, the value of the RU Allocation subfield of the User Info field including the AID12 subfield may be information corresponding to the STA indicated by the AID12 subfield. Also, the User Info field can indicate the coding method (UL FEC Coding Type), modulation method (UL HE-MCS, UL DCM), and transmission power (UL Target RSSI) used for the response to the trigger frame including the User Info field.

[0181] As described above, it may become a problem depending on in what PPDU format the TB PPDU transmitted simultaneously as a response to the trigger frame is transmitted. The triggering frame transmission method related to this will be described with reference to FIG. 17.

[0182] FIG. 17 shows the information indicated by the value of the AID12 subfield of the trigger frame according to an embodiment of the present invention.

[0183] The EHT STA according to an embodiment of the present invention can selectively transmit HE TB PPDU and EHT TB PPDU. Also, the NEXT STA can selectively transmit HE TB PPDU, EHT TB PPDU, and NEXT TB PPDU. Thereby, multiple wireless LAN standard STAs can be scheduled in one frame or one PPDU. Thereby, the usage efficiency of the transmission medium can be increased. For example, a HE STA that does not support the EHT standard and an EHT STA can respond with a HE TB PPDU in one frame.

[0184] Also, the information for selecting the TB PPDU format may be included in the trigger frame or the TRS or the PPDU including the trigger frame or the PPDU including the TRS.

[0185] According to an embodiment of the present invention, information regarding the responding TB PPDU format may exist at the MAC level. According to an embodiment of the present invention, the trigger frame may be classified into an HE trigger frame, an EHT trigger frame, and a NEXT trigger frame. Also, responses triggered by the HE trigger frame, the EHT trigger frame, and the NEXT trigger frame can be responded to with an HE TB PPDU, an EHT TB PPDU, and a NEXT TB PPDU, respectively.

[0186] Also, distinguishing the HE trigger frame, the EHT trigger frame, and the NEXT trigger frame may be the same as distinguishing the TB PPDU format responding to the trigger frame into an HE TB PPDU, an EHT TB PPDU, and a NEXT TB PPDU, respectively. That is, the format of the TB PPDU corresponding thereto may change according to the format of the trigger frame, and the next-generation trigger frame can also instruct the transmission of the previous-generation TB PPDU. That is, the EHT trigger frame can instruct the transmission of the HE TB PPDU and the EHT TB PPDU at the same time. However, the HE trigger frame cannot instruct the transmission of the EHT TB PPDU.

[0187] In a specific embodiment, it may be determined which trigger frame among the HE trigger frame, the EHT trigger frame, and the NEXT trigger frame the trigger frame corresponds to by the Frame Control field of the MAC header included in the trigger frame. For example, it may be determined which trigger frame among the HE trigger frame, the EHT trigger frame, and the NEXT trigger frame the trigger frame corresponds to by at least any one of the Type subfield, the Subtype subfield, or the Control Frame Extension subfield of the Frame Control field of the MAC header included in the trigger frame. For example, when the Type subfield, the Subtype subfield, or the Control Frame Extension subfield of the Frame Control field of the MAC header included in the trigger frame is a first value, the trigger frame may be classified as an HE trigger frame. Also, when the Type subfield, the Subtype subfield, or the Control Frame Extension subfield of the Frame Control field of the MAC header included in the trigger frame is a second value, the trigger frame may be classified as an EHT trigger frame. Also, when the Type subfield, the Subtype subfield, or the Control Frame Extension subfield of the Frame Control field of the MAC header included in the trigger frame is a third value, the trigger frame may be classified as a NEXT trigger frame. The value of the Type subfield of the Frame Control field of the MAC header is 01 b and the value of the Subtype subfield is 0010 bWhen it is the case, the trigger frame may be classified as a HE trigger frame. Each of the Type subfield, Subtype subfield, and Control Frame Extension subfield is limited to 2 bits, 4 bits, and 4 bits, respectively. For this reason, such an embodiment has the disadvantage of restricting the types that can be used in the future with limited bit field values.

[0188] In still other specific embodiments, the Common Info field included in the trigger frame may determine which trigger frame among the HE trigger frame, EHT trigger frame, and NEXT trigger frame the trigger frame corresponds to. For example, when the value of the Trigger Type subfield in the Common Info field of the trigger frame is the first value, the trigger frame may be classified as a HE trigger frame. When the value of the Trigger Type subfield in the Common Info field of the trigger frame is the second value, the trigger frame may be classified as an EHT trigger frame. When the value of the Trigger Type subfield in the Common Info field of the trigger frame is the third value, the trigger frame may be classified as a NEXT trigger frame. Specifically, when the value of the Trigger Type subfield in the Common Info field of the trigger frame is 0 to 7, the trigger frame may be classified as a HE trigger frame. Also, when the value of the Trigger Type subfield in the Common Info field of the trigger frame is not 0 to 7, the trigger frame may be classified as an EHT trigger frame or a NEXT trigger frame. Since the number of bits of the Trigger Type subfield is limited, such an embodiment has the disadvantage of restricting the trigger types that can be used in the future with limited bit field values.

[0189] In yet another specific embodiment, it may be determined which trigger frame among the HE trigger frame, the EHT trigger frame, and the NEXT trigger frame the trigger frame corresponds to based on the UL Length field included in the trigger frame. For example, when the remainder value obtained by dividing the value of the UL Length field of the trigger frame by 3 is a first value, the trigger frame may be classified as an HE trigger frame. When the remainder value obtained by dividing the value of the UL Length field of the trigger frame by 3 is a second value, the trigger frame may be classified as an EHT trigger frame. When the remainder value obtained by dividing the value of the UL Length field of the trigger frame by 3 is a third value, the trigger frame may be classified as a NEXT trigger frame. When the remainder value obtained by dividing the value of the UL Length field of the trigger frame by 3 is not 0, the trigger frame may be classified as an HE trigger frame. When the remainder value obtained by dividing the value of the UL Length field of the trigger frame by 3 is 1, the trigger frame may be classified as an HE trigger frame. When the remainder value obtained by dividing the value of the UL Length field of the trigger frame by 3 is 0, the trigger frame may be classified as an EHT trigger frame or a NEXT trigger frame. Also, in addition to the value of the UL Length field of the trigger frame, it may be determined which trigger frame among the HE trigger frame, the EHT trigger frame, and the NEXT trigger frame the trigger frame corresponds to based on at least one of the Format Identifier, the PHY Identifier, and the TB PPDU format signaling of the trigger frame.

[0190] In yet another specific embodiment, it may be determined which trigger frame among the HE trigger frame, the EHT trigger frame, and the NEXT trigger frame the trigger frame corresponds to based on the User Info field included in the trigger frame. Specifically, it may be determined which trigger frame among the HE trigger frame, the EHT trigger frame, and the NEXT trigger frame the trigger frame corresponds to based on the value of the AID12 subfield of the User Info field of the trigger frame. For example, it may be determined which trigger frame among the HE trigger frame, the EHT trigger frame, and the NEXT trigger frame the trigger frame corresponds to based on whether the value of the AID12 subfield of the User Info field of the trigger frame is a pre-specified value. At this time, the User Info field including the AID12 subfield indicating the type of the trigger frame may be the first User Info field in the User Info field list. The User Info field including the AID12 subfield indicating the type of the trigger frame may be located before the User Info field including the AID12 subfield indicating the AID of the STA. Thereby, the STA receiving the trigger frame can determine the type of the trigger frame earlier. In yet another specific embodiment, the User Info field including the AID12 subfield indicating the type of the trigger frame may be located after the User Info field for the HE STA in the User Info field list. Thereby, it is possible to prevent problems caused by the fact that the legacy STA, i.e., the HE STA, cannot determine the meaning of the value of the AID12 subfield. Also, the User Info field including the AID12 subfield indicating the type of the trigger frame may not include subfields other than the AID12 subfield. This is because the User Info field is for indicating the trigger frame type, and there may be no need for information other than the trigger frame type.In such an embodiment, the length of the User Info field varies according to the value of the AID12 subfield. FIG. 17 shows the meaning indicated by the value of the AID12 subfield when such an embodiment is applied. When the value of the AID12 subfield is the first value, the AID12 subfield can indicate that a trigger frame including the AID12 subfield triggers the transmission of an EHT TB PPDU. The first value may be 2047. When the value of the AID12 subfield is the second value, the AID12 subfield can indicate that a trigger frame including the AID12 subfield triggers the transmission of a NEXT TB PPDU. The second value may be 2048.

[0191] In yet other specific embodiments, the STA can determine the format of the TB PPDU to be transmitted as a response to the trigger frame based on the position of the User Info field that triggers the STA. Specifically, the STA can determine the format of the TB PPDU to be transmitted as a response to the trigger frame based on whether the User Info field that triggers the STA is located after a User Info field that includes an AID12 subfield having a pre-specified value. At this time, the STA can determine the format of the TB PPDU to be transmitted as a response to the trigger frame based on whether the User Info field that triggers the STA is located after a User Info field that includes an AID12 subfield having a first value and whether it is located after a User Info field that includes an AID12 subfield having a second value. In the embodiment of FIG. 17, when the User Info field that triggers the STA is located after a User Info field that includes an AID12 subfield having 2047, the STA can transmit an EHT TB PPDU as a response to the trigger frame. Also, when the User Info field that triggers the STA is located after a User Info field that includes an AID12 subfield having 2048, the STA can transmit a NEXT TB PPDU as a response to the trigger frame. Further, when the User Info field that triggers the STA is located after a User Info field that includes an AID12 subfield having 2047 and a User Info field that includes an AID12 subfield having 2048, the STA can transmit a NEXT TB PPDU as a response to the trigger frame. Also, when the User Info field that triggers the STA is located before a User Info field that includes an AID12 subfield having 2047 and a User Info field that includes an AID12 subfield having 2048, the STA can transmit a HE TB PPDU as a response to the trigger frame.

[0192] Depending on sub-fields of the User Info field other than the AID12 sub-field, it may be determined which trigger frame among the HE trigger frame, the EHT trigger frame, and the NEXT trigger frame the trigger frame corresponds to.

[0193] Depending on the Padding field of the trigger frame, it may be determined which trigger frame among the HE trigger frame, the EHT trigger frame, and the NEXT trigger frame the trigger frame corresponds to. For example, depending on whether the Padding field of the trigger frame contains a pre-specified value, it may be determined which trigger frame among the HE trigger frame, the EHT trigger frame, and the NEXT trigger frame the trigger frame corresponds to.

[0194] Also, these embodiments may be applied in combination. For example, elements that affect determining whether the above trigger frame is any one of the HE trigger frame, the EHT trigger frame, and the NEXT trigger frame may be determined in combination.

[0195] Also, these embodiments may be used to determine the format of the TB PPDU transmitted as a response to the TRS field.

[0196] FIG. 18 shows UL MU operation according to an embodiment of the present invention.

[0197] As described above, the trigger frame may include a TRS in the MAC frame header. The TRS may be included in the HT Control field as described above. Specifically, when the HT Control field includes the A-Control field, the TRS may be included. Also, the TRS may be included in the TRS Control field. The Control List field may be continuously positioned in the A-Control field. At this time, the Control List field may include the TRS.

[0198] A STA corresponding to the intended recipient of a MAC frame containing a TRS can transmit a PPDU based on the TRS. At this time, the TRS may include information (UL Data Symbols) regarding the length of the PPDU or frame transmitted as a response to the MAC frame containing the TRS by the STA. Information regarding the power for response transmission to the MAC frame containing the TRS (AP Tx Power, UL Target RSSI), the position and size of the RU used when transmitting a response to the MAC frame containing the TRS (RU Allocation), and information regarding the modulation method for response transmission to the MAC frame containing the TRS (UL HE-MCS) may be included.

[0199] The TRS may be defined according to each wireless LAN standard. At this time, a STA that has received a MAC frame containing a TRS can determine the format of the TB PPDU transmitted as a response to the TRS based on the format of the TRS, that is, which wireless LAN standard the TRS is defined in. Specifically, when a STA receives a HE TRS, the STA can transmit a HE TB PPDU as a response to the TRS. Also, when a STA receives an EHT TRS, the STA can transmit an EHT TB PPDU as a response to the TRS. Also, when a STA receives a NEXT TRS, the STA can transmit a NEXT TB PPDU as a response to the TRS. At this time, the STA can determine which wireless LAN standard the TRS is defined in based on the Control ID subfield of the A-Control subfield. The TRS may be distinguished between a HE TRS and a TRS that is not a HE TRS.

[0200] The format of the TRS may be determined by whether the HT Control field containing the TRS is an HE variant, an EHT variant, or a NEXT variant. When the HT Control field containing the TRS is an EHT variant, the TRS may be an EHT TRS. Also, when the HT Control field containing the TRS is a NEXT variant, the TRS may be a NEXT TRS. Further, the format of the TRS may determine whether the HT Control field is an HE variant, an EHT variant, or a NEXT variant based on the value of a pre-specified bit among the bits of the HT Control field containing the TRS. For example, when the values of the first and second bits (B0, B1) of the HT Control field are 11 b the HT Control field may be an HE variant. Also, whether the HT Control field is an HE variant, an EHT variant, or a NEXT variant may be determined based on the first and second bits (B0, B1) of the HT Control field and an additional bit, for example, the 32nd bit (B31).

[0201] In the embodiment of FIG. 18, when the TRS is included in the HE PPDU, the STA that receives the HE PPDU transmits an HE TB PPDU as a response to the TRS. When the TRS is included in the EHT PPDU, the STA that receives the EHT PPDU transmits an EHT TB PPDU as a response to the TRS. When the TRS is included in the NEXT PPDU, the STA that receives the NEXT PPDU transmits a NEXT TB PPDU as a response to the TRS.

[0202] Also, depending on the PPDU format including the TRS, the information indicated by the subfield included in the TRS may change. When the TRS is included in a HE PPDU, a subfield related to the MCS included in the TRS, such as the UL HE-MCS subfield, can indicate a value corresponding to the HE MCS table. Also, when the TRS is included in an EHT PPDU, a subfield related to the MCS included in the TRS, such as the UL HE-MCS subfield, can indicate a value corresponding to the EHT MCS table. Also, when the TRS is included in a NEXT PPDU, a subfield related to the MCS included in the TRS, such as the UL HE-MCS subfield, can indicate a value corresponding to the NEXT MCS table. Also, depending on the PPDU format including the TRS, the information indicated by the RU Allocation subfield may change.

[0203] FIG. 19 is a diagram showing a method for sharing a TXOP according to an embodiment of the present invention.

[0204] Referring to FIG. 19, part or all of the TXOP set by the AP is shared with a non-AP STA, and the non-AP STA can use the shared TXOP to transmit a PPDU (PLCP Protocol Data Unit) to another non-AP STA (third STA) and / or the AP. Hereinafter, in the present invention, sharing the TXOP with other STAs can be referred to as TXOP sharing. Also, the STA may be an AP or an AP-STA that transmits a trigger frame, or a non-AP STA that receives a trigger frame. Also, the STA may share the TXOP or the TXOP may be shared.

[0205] Specifically, after transmitting a frame for setting a TXOP, the STA can set (or acquire) the TXOP by receiving a response thereto. After setting the TXOP, the STA can achieve TXOP sharing by sharing the set TXOP. The response to the frame for setting the TXOP may include information regarding the length of the TXOP, and the length of the TXOP may be greater than 0. At this time, the response to the frame for setting the TXOP may be an immediate response and may be transmitted after a specific time (e.g., SIFS) from the end of the frame for setting the TXOP (e.g., PPDU).

[0206] The length of the TXOP may be indicated based on the duration information included in the frame transmitted by the STA. For example, the duration information may be included in the duration / ID field of the MAC header of the PPDU, and the length of the TXOP can be based on the duration information. The length of the TXOP may be included in the preamble included in the PPDU of the frame transmitted by the STA. That is, the duration information may be included in the TXOP field included in the signaling field of the PPDU, and the signaling field may be the HE-SIG-A field or the U-SIG field.

[0207] TXOP sharing may be shared within the set TXOP, and one or more TXOPs may be shared between the set TXOPs. That is, one or more TXOPs may be shared with other STAs within the TXOP set by the STA.

[0208] A STA that has shared a TXOP can transmit a PPDU to the STA that shared the TXOP or another STA during the shared TXOP. At this time, the transmitted PPDU may be a PPDU that is not a TB PPDU (for example, a non-TB PPDU). That is, a STA that has shared a TXOP can transmit a PPDU without receiving a trigger frame from the AP during the shared TXOP. In other words, a STA that has shared a TXOP can use the allocated RUs by the trigger frame transmitted when the TXOP is shared and transmit a PPDU without receiving an additional trigger frame until the shared TXOP ends, even if a separate RU is not individually allocated by the trigger frame during the shared TXOP. Therefore, examples of PPDUs transmitted by a STA during a shared TXOP can include non-HT PPDU, HE PPDU, VHT PPDU, HE SU PPDU, or EHT MU PPDU.

[0209] In the sharing of a TXOP, during the shared TXOP, a STA that has shared the TXOP can transmit a frame to the STA that shared the TXOP or a third STA (yet another STA). That is, when the AP sets a TXOP and shares part or all of the set TXOP with a STA, the STA that has shared the TXOP can transmit a frame to the AP or a third STA that shared the TXOP. At this time, since the frame transmitted by the STA to the third STA is a frame transmitted between non-AP STAs, it can be a P2P (peer to peer) frame.

[0210] Such sharing of the TXOP may be set by a specific frame. That is, it may be instructed that part or all of the TXOP set by the specific frame is shared, and the STA can receive the frame and use the shared TXOP. At this time, the specific frame may be transmitted by the STA that shares the TXOP. For example, TXOP sharing may be performed by a trigger frame transmitted by the AP. In this case, the trigger frame for TXOP sharing may be a specific type of trigger frame (for example, a MU-RTS frame, or a MU-RTS trigger frame, etc.), and may be identified by the value of the trigger type subfield of the trigger frame described in FIG. 16. That is, when the value of the trigger type subfield is set to a preset value (for example, "3"), the STA that receives the trigger frame can recognize that the TXOP is shared and can transmit a PPDU with the shared TXOP.

[0211] The MU-RTS frame, which is a frame for sharing the TXOP, may be a frame that instructs one or more STAs to transmit a CTS frame. For example, a CTS frame may be transmitted as an immediate response to the MU-RTS frame, and the CTS frame may be a non-HT PPDU. Hereinafter, in the present invention, the MU-RTS frame for sharing the TXOP may be referred to as a modified MU-RTS frame or a MU-RTS TXS trigger frame. However, it is not limited thereto, and the frame for sharing the TXOP may have various names.

[0212] The sharing of part or all of the TXOP may be set only for one STA or for one or more STAs. That is, in the sharing of the TXOP using a frame, one or more STAs for TXOP sharing may be instructed by the frame. At this time, the sharing of the TXOP may be set within the TXOP set by the STA that shares it as described above. That is, the shared TXOP does not exceed the TXOP set by the STA that shares it.

[0213] The duration of the shared TXOP may be indicated through a specific frame (e.g., modified MU-RTS frame) for sharing of the TXOP. For example, the modified MU-RTS frame may include a UL length subfield, and the UL length subfield may include the duration of the shared TXOP. At this time, the UL length subfield may be the UL length subfield described in FIG. 16. The UL length subfield may include information regarding the length of the indicated TB PPDU (or interval information for transmission of the TB PPDU) when the trigger frame indicates transmission of the TB PPDU.

[0214] Whether the transmitted MU-RTS frame is a MU-RTS frame (modified MU-RTS frame) for sharing of the TXOP or a MU-RTS frame not used for sharing of the TXOP may be indicated by a specific field included in the frame. For example, when the value of the specific field included in the frame is a preset value, the MU-RTS frame may be a modified MU-RTS frame for TXOP sharing. At this time, the specific frame may be a GI And HE-LTF type subfield. For example, when the type field included in the trigger frame indicates a MU-RTS frame, whether the MU-RTS frame is a trigger frame for sharing of the TXOP may be identified by the value of the GI And HE-LTF type subfield. That is, when the GI And HE-LTF type subfield is set to a preset value, the trigger frame may be a trigger frame for sharing of the TXOP (e.g., modified MU-RTS frame or MU-RTS TXS trigger frame).

[0215] Alternatively, whether the received frame is a MU-RTS frame (modified MU-RTS frame or MU-RTS TXS trigger frame) for sharing TXOP may be determined based on whether a specific field is included in the MU-RTS frame and / or the number of specific fields. At this time, the specific field may be the user information field (User Info field) or the user information list field (User Info List field) described in FIG. 16. Specifically, based on the number of user information fields included in the MU-RTS frame, it may be determined whether the received MU-RTS frame is a frame for sharing TXOP. For example, when the MU-RTS frame does not include a user information field (when the number of user information fields is "0"), the MU-RTS frame may be a frame for sharing TXOP. At this time, when the MU-RTS frame is not a frame for sharing TXOP, the MU-RTS frame may be a MU-RTS frame that instructs one or more STAs to transmit an existing CTS frame, or the existing MU-RTS frame may be a MU-RTS frame defined in the 802.11ax standard.

[0216] Immediately after a CTS frame is transmitted as a response to an existing MU-RTS frame, the STA (e.g., AP) that transmitted the existing MU-RTS frame can transmit a frame or PPDU. Also, immediately after a CTS frame is transmitted as a response to a modified MU-RTS frame, the STA that transmitted the CTS frame can transmit a frame or PPDU. Alternatively, a STA that has received TXOP sharing as a response to a modified MU-RTS frame can transmit a frame or PPDU that is not a CTS frame. At this time, the frame and PPDU may be, respectively, a frame transmitted by a STA that has received TXOP sharing during the shared TXOP described above and a PPDU including a frame transmitted by a STA that has received TXOP sharing during the shared TXOP. That is, the frame or PPDU may be directed to the AP or may be a P2P frame.

[0217] In the present invention, what is denoted as the MU-RTS frame may be an existing MU-RTS frame. That is, what is denoted as the MU-RTS frame in the present invention may be an MU-RTS frame that is not a modified MU-RTS frame.

[0218] According to an embodiment of the present invention, a CTS frame may be transmitted as a response to the modified MU-RTS frame. The CTS frame may be transmitted by a STA that receives TXOP sharing. In such a case, the STA that receives TXOP sharing can transmit a frame immediately after transmitting the CTS frame. The STA that receives TXOP sharing can transmit a frame immediately after transmitting a PPDU including the CTS frame. The frame transmitted immediately after transmitting the CTS frame may be included in the PPDU transmitted by the STA that received TXOP sharing during the aforementioned shared TXOP. Or, the frame transmitted immediately after transmitting the CTS frame may be transmitted included in the aforementioned non-TB PPDU. Also, in the present invention, transmitting immediately means that it can be transmitted after the SIFS or PIFS time from the end of the PPDU including the CTS frame. The CTS frame can serve to notify that the STA has received TXOP sharing.

[0219] According to still other embodiments, a CTS frame may not need to be transmitted in response to a modified MU-RTS frame. Also, immediately after the modified MU-RTS frame, a STA receiving TXOP sharing can transmit a frame. Or, immediately after a PPDU including the modified MU-RTS frame, a STA receiving TXOP sharing can transmit a PPDU. The frame transmitted at this time may be included in the PPDU transmitted by the STA that received TXOP sharing during the aforementioned shared TXOP. Or, the frame transmitted at this time may be transmitted included in the aforementioned non-TB PPDU. Also, in the present invention, "transmitted immediately afterwards" may mean transmitted after a SIFS or PIFS time from the end of the PPDU including the modified MU-RTS frame.

[0220] According to one embodiment, the modified MU-RTS frame may include signaling as to whether a STA receiving TXOP sharing has to transmit a CTS frame. According to one embodiment, when transmitting a frame that a STA receiving TXOP sharing sends to an AP, it is possible to use a TXOP shared without a CTS frame. Also, when a STA receiving TXOP sharing transmits a P2P frame, it is possible to transmit a CTS frame and use the shared TXOP. Also, when a STA receiving TXOP sharing transmits a P2P frame, the RA field of the CTS frame transmitted immediately after the modified MU-RTS frame can be set as the MAC address of the STA that transmitted the modified MU-RTS frame. This is because when a STA receiving TXOP sharing does not transmit a frame including the address of the STA that transmitted the modified MU-RTS frame after receiving the modified MU-RTS frame, it is difficult for the STA sharing the TXOP to know whether the STA receiving TXOP sharing successfully received the modified MU-RTS frame.

[0221] Referring to FIG. 19, STA1 and STA2 may exist and may be associated with each other. Also, STA1 may be an AP. STA2 may be a non-AP STA. STA1 is capable of transmitting a MU-RTS frame. The MU-RTS frame may be an existing MU-RTS frame. The MU-RTS frame may include duration information regarding the TXOP duration. The MU-RTS frame can solicit a CTS frame from one or more STAs. At this time, the one or more STAs may include STA2. STA2 can transmit a CTS frame as a response to the MU-RTS frame. In this case, STA1 can become the TXOP holder. The TXOP holder may be the STA that has obtained the TXOP. The TXOP holder can transmit the frame to be transmitted during the TXOP. Also, in this case, STA2 can become the TXOP responder. The TXOP responder may be the STA that has transmitted a response to the frame sent by the TXOP holder. The TXOP responder is capable of transmitting a response to the frame transmitted by the TXOP holder during the TXOP. Or, the TXOP responder is capable of transmitting the frame permitted by the TXOP holder during the TXOP. In the embodiment of FIG. 19, an example in which the TXOP is obtained based on the exchange of the MU-RTS frame and the CTS frame has been described, but the present invention is not limited to this, and is also applicable to the case where the TXOP is obtained based on other frame exchanges.

[0222] In FIG. 19, after STA1 obtains a TXOP, it is possible to perform TXOP sharing. For example, STA1 can transmit a modified MU-RTS frame, which is a frame for notifying TXOP sharing. For example, the modified MU-RTS frame can be transmitted to STA2. The TA (transmitter address) of the modified MU-RTS frame may be set to the MAC address of STA1 or a value based on the MAC address of STA1. The RA (receiver address) of the modified MU-RTS frame may be set to the MAC address of STA2 or a value based on the MAC address of STA2. Also, the User Info field included in the modified MU-RTS frame can indicate STA2 with the AID12 sub-field value. That is, the User Info field included in the modified MU-RTS frame can indicate the 12 LSBs of the AID of STA2 with the AID12 sub-field value. The modified MU-RTS frame may include information regarding the duration of the shared TXOP.

[0223] According to one embodiment, STA2 can transmit a CTS frame as a response to the modified MU-RTS frame. Also, after transmitting the CTS frame, STA2 can transmit a frame. The frame transmitted after STA2 transmits the CTS frame does not have to be a CTS frame. According to still other embodiments, STA2 does not have to transmit a CTS frame as a response to the modified MU-RTS frame. In this case, after the modified MU-RTS frame is transmitted, STA2 can transmit a frame that is not a CTS frame. Also, according to one embodiment, the frame that is not a CTS frame transmitted after STA2 receives the modified MU-RTS frame may be a frame transmitted to STA1. According to other embodiments, the frame that is not a CTS frame transmitted after STA2 receives the modified MU-RTS frame may be a frame transmitted to STA3.

[0224] For example, the AP can set its TXOP by sending a trigger frame to a non-AP STA (or STA). At this time, when the AP attempts to share part or all of the TXOP set by the AP with the non-AP STA that sent the trigger frame, the AP can set a specific field of the trigger frame (e.g., the GI And HE-LTF type subfield) to a pre-set value and then send it. At this time, the specific field can be called the GI And HE-LTF type / triggered TXOP sharing mode subfield. Specifically, when the AP does not share the TXOP set by the AP, the GI And HE-LTF type / triggered TXOP sharing mode subfield is set to "0" and can be interpreted as the GI And HE-LTF type subfield. However, when the AP shares the TXOP set by the AP, the GI And HE-LTF type / triggered TXOP sharing mode subfield is set to a value of "1" or "2" and can be interpreted as the triggered TXOP sharing mode subfield. If the value of the GI And HE-LTF type / triggered TXOP sharing mode subfield is "1" or "2", the trigger frame can be called a modified MU-RTS frame or a MU-RTS TXS trigger frame. When the AP shares part or all of the TXOP set by the AP, the GI And HE-LTF type / triggered TXOP sharing mode subfield of the trigger frame for TXOP sharing indicates the TXOP sharing mode. For example, the GI And HE-LTF type / triggered TXOP sharing mode subfield indicates whether the TXOP sharing is shared only in the transmission and reception with the AP that set the TXOP, or is also shared in the transmission and reception with a third STA (or other STA) in addition to the AP. That is, when the value of the GI And HE-LTF type / triggered TXOP sharing mode subfield is "1", the STA can send PPDUs only to the AP during the shared TXOPs.However, when the value of the GI And HE-LTF type / triggered TXOP sharing mode subfield is "2", during the shared TXOP, the STA can transmit PPDUs not only to the AP but also to another STA. That is, when the value of the GI And HE-LTF type / triggered TXOP sharing mode subfield is "2", the STA can also perform P2P communication during the shared TXOP.

[0225] Table 1 below shows an example of the presence or absence of TXOP sharing and the mode according to the value of the GI And HE-LTF type / triggered TXOP sharing mode subfield.

[0226]

Table 1

[0227] FIG. 20 is a diagram showing a method related to the sharing of TXOP and NAV setting according to an embodiment of the present invention.

[0228] The embodiment of FIG. 20 can be an embodiment for explaining the problem that it is difficult to perform the operations described in FIG. 19 and the solution thereto. The content described in FIG. 19 may be omitted.

[0229] According to an embodiment of the present invention, the STA can set the NAV (network allocation vector) based on the duration information included in the received frame or the received PPDU. Based on whether the NAV is set or not, it may be determined whether the virtual CS (carrier sense) result is idle or busy. When the NAV value is 0, the virtual CS result may be idle. When the NAV value is greater than 0, the virtual CS result may be busy. The Physical CS may be CCA (clear channel assessment). If at least one of the virtual CS or the physical CS is busy, the CS result may be busy. If both the virtual CS and the physical CS are idle, the CS result may be idle. Also, there may be a case where the STA includes a large number of NAVs. For example, the STA may include an intra-BSS NAV and a basic NAV. The intra-BSS NAV may be the NAV set by an intra-BSS frame or an intra-BSS PPDU. The Regular NAV may be the NAV set by an inter-BSS frame or an inter-BSS PPDU or a frame or PPDU for which it cannot be determined whether it is intra-BSS or inter-BSS. Also, when at least one of the intra-BSS NAV and the basic NAV is a value greater than 0, the virtual CS may be busy. Or, when at least one of the intra-BSS NAV and the basic NAV is a value greater than 0, it can be said that the NAV is a value greater than 0. When both the intra-BSS NAV and the basic NAV are 0, the virtual CS may be idle. Or, when both the intra-BSS NAV and the basic NAV are 0, it can be said that the NAV is 0.

[0230] For a certain STA, an intra-BSS frame or intra-BSS PPDU may be a frame or PPDU determined to be transmitted from the same BSS as the STA. For a certain STA, an inter-BSS frame or inter-BSS PPDU may be a frame or PPDU determined to be transmitted from a BSS different from the STA. Also, the determination as to whether it is transmitted from the same BSS or from a different BSS may be determined based on the BSS color field included in the preamble of the PPDU, the address field included in the MAC header, etc. For example, when the BSS color field or the address field has a value corresponding to the same BSS, it can be determined as an intra-BSS frame or intra-BSS PPDU. Also, when the BSS color field or the address field does not include a value corresponding to the same BSS, it can be determined as an inter-BSS frame or inter-BSS PPDU. The address field may include an RA field, a TA field, a BSSID field, etc.

[0231] According to one embodiment, when the resource allocation field (Resource Allocation (RA) field) of the received frame is not its own MAC address, the STA can set the NAV based on the received frame. Or, the STA can set the NAV based on the received trigger frame. More specifically, the STA can set the NAV based on a trigger frame that is a received intra-BSS frame. At this time, the NAV may be an intra-BSS NAV. At this time, the NAV can be set regardless of whether the trigger frame triggers the STA. Or, the STA can set the NAV when the received frame or the received PPDU does not instruct an immediate response from the STA.

[0232] According to one embodiment of the present invention, when the CS is busy, the STA may not be able to transmit a frame or PPDU.

[0233] According to an embodiment of the present invention, a STA with a NAV set to a value greater than 0 may not be able to transmit a frame or PPDU. More specifically, a STA with a NAV set to a value greater than 0 may not be able to transmit a frame or PPDU when it does not meet the already set conditions.

[0234] According to an embodiment, a STA can transmit regardless of the NAV (or without considering the NAV) when the received frame is addressed to the STA and requires an immediate response. More specifically, the received frame may not be an RTS frame or a trigger frame. That is, even if the NAV is set to a value greater than 0, a STA can transmit regardless of the NAV when the received frame is addressed to the STA and requires an immediate response. Also, when the frame is addressed to the STA, it may include the case where the RA field of the frame is set as the address of the STA. Or, when the frame is addressed to the STA, it may include the case where the frame includes an identifier corresponding to the STA. The identifier may include a MAC address, an AID (association ID), an ID based on the MAC address, an ID based on the AID, and the like.

[0235] According to still other embodiments, when the received frame is transmitted from the TXOP holder, the STA can transmit a response thereto regardless of the NAV. At this time, the NAV may be the NAV set by the frame or PPDU sent by the TXOP holder. Alternatively, the NAV may be an intra-BSS NAV. Further, the received frame may be an RTS frame. That the frame is transmitted from the TXOP holder can be determined based on the TA field included in the frame. The STA can store the TXOP holder address. If the STA receives an RTS frame transmitted by the TXOP holder and the RTS frame is addressed to the STA, the STA can respond to the RTS frame without considering the NAV. At this time, a CTS frame can be transmitted as a response to the RTS frame.

[0236] According to yet another embodiment, when the STA receives a trigger frame, it can send a response thereto regardless of the NAV. At this time, the NAV may be limited to the intra-BSS NAV. Therefore, when the NAV is set by a STA in the same BSS or an AP in the same BSS, the STA can send a response thereto when instructed by the trigger frame, regardless of the NAV. When the STA receives a trigger frame, it can determine whether to send a response thereto without considering the intra-BSS NAV and not considering the basic NAV. Also, when the STA receives a trigger frame, it can determine whether to send a response to the trigger frame based on the CS result. For example, the trigger frame may include signaling that indicates whether to determine whether to send a response based on the CS result when the trigger frame is received. For example, the signaling may be the CS Required subfield shown in FIG. 16. If the CS Required subfield determines and indicates whether to respond based on the CS result, the STA responds to the trigger frame when the virtual CS and the physical CS indicate idle, and does not have to respond to the trigger frame when the virtual CS or the physical CS indicates busy. At this time, it is possible not to consider the intra-BSS NAV in the virtual CS and to consider the basic NAV. Also, if the CS Required subfield instructs to respond without depending on the CS result, the STA can respond to the trigger frame without confirming the CS result.

[0237] In the embodiment of FIG. 19, since the STA that has received the modified MU-RTS frame has the NAV set, it may be impossible to send a frame other than the CTS frame during the shared TXOP. This will be further described with reference to FIG. 20.

[0238] The content described with reference to FIG. 19 in connection with FIG. 20 may be omitted. Referring to FIG. 20, STA1 and STA2 may exist and may be associated with each other. Also, STA1 may be an AP. STA2 may be a non-AP STA. STA1 can transmit a MU-RTS frame. Also, STA2 can transmit a CTS frame in response to the MU-RTS frame. At this time, the fact that STA2 transmits a CTS frame may be because the physical CS result of STA2 is idle and the basic NAV is not set. Or, the fact that STA2 transmits a CTS frame may be because STA2 has received a frame addressed to itself and requiring an immediate response. At this time, even when another frame exchange occurs in addition to the exchange of the MU-RTS frame and the CTS frame, since the frame is addressed to STA2 and requires an immediate response based on the frame received from STA1, STA2 can transmit a frame to respond. Also, STA2 may set the NAV based on a frame other than the MU-RTS frame or the MU-RTS frame transmitted by STA1. At this time, the NAV may be an intra-BSS NAV.

[0239] In addition, STA1 can perform TXOP sharing with STA2. That is, STA1 can send a modified MU-RTS frame to STA2. At this time, as described above, STA2 can use the shared TXOP to 1) send a CTS frame and then send other frames, or 2) send other frames without sending a CTS frame. However, at this time, since the NAV is set, it may be difficult for STA2 to send a frame. For example, before STA1 allocates the shared TXOP, the NAV may be set by a frame sent by STA2 to obtain the TXOP. That is, STA2 may receive a frame sent before STA1 sends the modified MU-RTS frame, and the NAV may be set. Or, before receiving the modified MU-RTS frame addressed to itself, STA2 may receive a frame sent from another STA during the same TXOP, and the NAV may be set. Or, the NAV may be set based on the modified MU-RTS frame addressed to itself. That is, since STA2 should receive at least the modified MU-RTS frame when using the shared TXOP, the NAV may be set. Therefore, it may be difficult for STA2 to utilize the shared TXOP to send a frame.

[0240] Accordingly, according to one embodiment of the present invention, a STA that has received TXOP sharing can transmit a frame regardless of the NAV. For example, a STA that has received TXOP sharing can transmit a frame during the shared TXOP regardless of the NAV. For example, a STA with shared TXOP can transmit a frame even if the NAV is set (or if the NAV is greater than 0). According to a more specific embodiment, at this time, the NAV can be limited to the intra-BSS NAV. For example, a STA with shared TXOP can transmit a frame regardless of the intra-BSS NAV. Also, a STA with shared TXOP may not be able to transmit a frame when the basic NAV is set. Or, a STA with shared TXOP can transmit a frame regardless of the NAV set by a frame or PPDU sent by the associated AP. For example, when the NAV of a STA with shared TXOP is set by a frame sent by a STA that is not the associated AP, it may not be possible to transmit a frame during the shared TXOP.

[0241] That is, a STA can transmit a PPDU regardless of the NAV set within the shared TXOP when the TXOP is shared. Specifically, when the AP transmits a trigger frame (modified MU-RTS frame or MU-RTS TXS trigger frame) for TXOP sharing, the NAV may be set by the AP within the shared TXOP. In this case, a STA with shared TXOP may not be able to transmit a PPDU because of the NAV set within the shared TXOP. Therefore, a STA with shared TXOP can transmit a PPDU by ignoring the NAV set by the AP that shared the TXOP within the shared TXOP.

[0242] In the present invention, what is shown as a frame can also apply the invention in place of the PPDU including the frame.

[0243] Also, at this time, the frame transmitted by the TXOP - shared STA regardless of the NAV may be transmitted after the SIFS from the previous PPDU.

[0244] According to still other embodiments, when the TXOP - shared STA transmits a frame, if the frame is transmitted after the PIFS from the previous PPDU, it is possible to consider the NAV.

[0245] Referring to FIG. 20, the NAV of STA2 may be set based on the MU-RTS frame or the modified MU-RTS frame. For example, the intra-BSS NAV may be set. Alternatively, the NAV of STA2 may be set based on the intra-BSS frame. Alternatively, the NAV of STA2 may be set based on the frame transmitted by the combined AP. In this embodiment, the NAV may be a general term for the NAV as described above. STA1 can perform TXOP sharing with STA2. STA2 can receive TXOP sharing by the modified MU-RTS frame. When transmitting a frame in the shared TXOP, STA2 can transmit the frame regardless of the NAV. According to one embodiment, the frame transmitted at this time may be the frame transmitted immediately after the CTS frame transmitted immediately after the received modified MU-RTS frame. According to still another embodiment, the frame transmitted at this time may be the frame transmitted immediately after the received modified MU-RTS frame. Also, according to one embodiment, the frame transmitted by STA2 may be the frame sent to the STA that transmitted the modified MU-RTS frame. That is, the RA field of the transmitted frame may be set to the value of the TA field of the received modified MU-RTS frame. Alternatively, the RA field of the transmitted frame may be set to the MAC address of the AP. According to other embodiments, the frame transmitted by STA2 may be the frame transmitted to STA3. Also, the phrase "transmitting a frame immediately afterwards" can mean that the start time of transmission of the PPDU including the frame is after SIFS from the end of the previous PPDU.

[0246] FIG. 21 is a diagram showing TXOP sharing and CTS frame transmission according to an embodiment of the present invention.

[0247] The embodiment of FIG. 21 may be a method for solving the problems described in FIGS. 19 and 20. Therefore, the foregoing content may be omitted from the description.

[0248] According to an embodiment of the present invention, in order to solve the problem that it is difficult to transmit a frame during a shared TXOP considering NAV, the frame sequence can be continued so that the condition for transmitting a response regardless of NAV is satisfied.

[0249] According to an embodiment of the present invention, a STA that has received TXOP sharing can transmit a CTS-to-self frame as a response to a modified MU-RTS frame. The CTS-to-self frame may be a CTS frame in which the RA field is set to the MAC address of the STA that transmits the CTS-to-self frame. In such a case, when the STA that shares the TXOP receives a frame including the MAC address of the STA that receives the TXOP sharing after transmitting the modified MU-RTS frame, it can be determined that the shared TXOP allocation has been successful.

[0250] Referring to FIG. 21, STA2 can receive a modified MU-RTS frame from STA1. Further, STA2 can transmit a CTS-to-self frame immediately after the modified MU-RTS frame. That is, STA2 can transmit a CTS frame by setting the RA field of the CTS frame to the MAC address of STA2. In such a case, the CTS-to-self frame transmitted by STA2 can be regarded as a frame addressed to itself and requesting an immediate response. Or, STA2 can be regarded as having received a frame addressed to itself and requesting an immediate response for transmitting the CTS-to-self frame. Therefore, even if the NAV is set, STA2 can transmit a frame immediately after the CTS-to-self frame.

[0251] According to an embodiment of the present invention, the RA field of the CTS frame transmitted as a response to the RTS frame or the MU-RTS frame can be set to the TA field value of the RTS frame or the MU-RTS frame, or a value obtained by setting the Individual / Group bit to 0 in the TA field value. However, an additional method for setting the RA field of the CTS frame may be defined to transmit the CTS-to-self frame as described with reference to FIG. 21. For example, the RA field of the CTS frame transmitted as a response to the modified MU-RTS frame can be set to the MAC address of the STA that transmits the CTS frame.

[0252] According to an embodiment of the present invention, a STA that has received TXOP sharing can perform recovery within the shared TXOP. That is, a STA that has received TXOP sharing can perform recovery when a frame transmitted by itself fails within the shared TXOP. For example, a STA that has received TXOP sharing can transmit a frame after PIFS when a frame transmitted by itself fails within the shared TXOP. According to an embodiment of the present invention, the TXOP holder can perform recovery. In addition to this, when the TXOP holder performs TXOP sharing, a STA that has received TXOP sharing can perform recovery. That is, recovery can be performed when 1) it is a TXOP responder or 2) a STA that is neither a TXOP holder nor a TXOP responder becomes a STA that has received TXOP sharing. Also, a STA that has received TXOP sharing can perform a recovery operation when a frame other than the first CTS frame is transmitted after receiving a modified MU-RTS frame and the frame other than the CTS frame fails. For example, the TXOP holder cannot perform a recovery operation when the first frame transmitted at the beginning of the sequence fails, and at this time, it can be said that the TXOP was not obtained. However, a STA that has received TXOP sharing can also perform a recovery operation when a frame other than the first CTS frame transmitted within the shared TXOP fails.

[0253] Referring to FIG. 21, STA2 can transmit the UL frame shown in the drawing and perform a recovery operation if it fails. That is, STA2 can transmit the UL frame and retransmit the frame if it has not received the DL frame shown in the drawing. At this time, the frame to be retransmitted can start transmission after PIFS from the end of the PPDU including the failed UL frame shown in the drawing. Also, it is possible to check whether the channel is idle during recovery. Further, in the recovery operation performed by the STA that has received TXOP sharing, only the physical CS can be considered without considering the virtual CS.

[0254] FIG. 22 is a diagram showing an example of a trigger frame for sharing TXOP according to an embodiment of the present invention.

[0255] As described with reference to FIG. 19, whether it is a modified MU-RTS frame can be based on the number of user information fields. However, the trigger frame defined in the 802.11ax standard may be designed without considering that its functions will be extended in subsequent standards. Therefore, for example, the Common Info field shown in FIG. 16(b) may lack signaling space to include extended functions. Thus, according to an embodiment of the present invention, the user information field including the already set AID12 subfield value may have a format different from that shown in FIG. 16(c). Also, the user information field including the already set AID12 subfield value may include information corresponding to all or one or more recipients of the trigger frame including the user information field. For example, the user information field including the already set AID12 subfield value may include at least one of PHY version ID, bandwidth extension, bandwidth, spatial reuse, and U-SIG reserved bits. Also, the already set AID12 subfield value can be based on a value not assigned as an actual AID. The already set AID12 subfield value may be the 12 LSBs of a value not assigned as an actual AID. For example, the already set AID12 subfield value may be 2007.

[0256] Also, the extended functions mentioned above may include, for example, an increased bandwidth. For example, the bandwidth may be extended from a maximum of 160 MHz to a maximum of 320 MHz. Also, the extended functions may include information for generating the U-SIG field.

[0257] Thus, according to an embodiment of the present invention, in order to use the extended functions even within a modified MU-RTS frame or a shared TXOP, the modified MU-RTS frame may include a user information field including the already set AID12 subfield value mentioned above.

[0258] According to an embodiment of the present invention, the modified MU-RTS frame may not include any user information field or may include only a user information field including the already mentioned and set AID12 sub-field value in the user information field. That is, when the received trigger frame does not include any user information field or includes only a user information field including the already mentioned and set AID12 sub-field value, the trigger frame can be determined as a modified MU-RTS frame. Or, when the received MU-RTS frame does not include any user information field or includes only a user information field including the already mentioned and set AID12 sub-field value, the MU-RTS frame can be determined as a modified MU-RTS frame. At this time, the STA receiving TXOP sharing may be indicated by the RA field of the trigger frame.

[0259] Referring to FIG. 22, in the modified MU-RTS frame, the type subfield may be set to MU-RTS. Also, the modified MU-RTS frame may have one user information field. At this time, the AID12 subfield included in the user information field may be set to a value that has already been set. At this time, the already set value may be a value that is not assigned as an AID. Also, the already set value may be a value different from the 12 least significant bits of the AID of the STA having the RA field value of the modified MU-RTS frame as the MAC address. For example, the already set value may be 2007. Or, the modified MU-RTS frame may not include any user information fields. That is, when the Type of the trigger frame is set as an MU-RTS frame, the STA that has received the trigger frame can determine that the trigger frame is a modified MU-RTS frame when the trigger frame does not include any user information fields or includes only the user information field including the AID12 subfield with the already set value.

[0260] FIG. 23 is a diagram showing the NAV time out according to an embodiment of the present invention.

[0261] According to an embodiment of the present invention, the STA can reset the set NAV. For example, when the NAV is set based on an RTS frame or a MU-RTS frame, it is possible to reset the NAV. More specifically, when the NAV is set based on an RTS frame or a MU-RTS frame, it is possible to reset the NAV if the reception of the PPDU cannot be successfully started during the already set time. Such an operation can be called NAV timeout or NAVTimeout. The already set time can be called the NAVTimeout period or the NAV timeout period. The NAVTimeout period may start when a PHY-RXEND.indication primitive corresponding to the RTS frame or the MU-RTS frame is received.

[0262] In an embodiment of the present invention, setting the NAV based on an RTS frame or a MU-RTS frame can mean that the most recent NAV update was made based on an RTS frame or a MU-RTS frame. If the duration information received by the STA from the RTS frame or the MU-RTS frame is larger than the current NAV value of the STA, the NAV can be set or updated based on the RTS frame or the MU-RTS frame. The duration information can be obtained based on the Duration / ID field included in the MAC header, or based on the TXOP duration or the TXOP field included in the preamble of the PPDU.

[0263] Also, in an embodiment of the present invention, when successfully starting PPDU reception, a PHY-RXSTART.indication primitive can be received. Alternatively, when successfully starting PPDU reception, a PHY-RXSTART.indication primitive may be issued. The PHY-RXSTART.indication primitive may be transmitted from the PHY to the MAC. For example, the PHY-RXSTART.indication primitive may be generated when the PHY receives a valid start of a PPDU. Also, receiving a valid start of a PPDU can mean receiving a valid PHY header. Further, the PHY-RXSTART.indication primitive can be generated after determining the PPDU format. When the PHY-RXSTART.indication primitive is generated, the PHY can maintain the physical medium in a busy status between the length of the PPDU or the length indicated by the PPDU preamble. If the PHY-RXSTART.indication primitive is generated, even if reception fails in the middle of the PPDU, the PHY can maintain the physical medium in a busy status between the length of the PPDU or the length indicated by the PPDU preamble. Also, a PHY-RXEND.indication may be generated when PPDU reception is completed.

[0264] According to an embodiment of the present invention, the aforementioned NAV timeout period may be based on the response time for an RTS frame or a MU-RTS frame. That is, when the response to an RTS frame or a MU-RTS frame is a CTS frame, the NAV timeout period may be based on the CTS frame time. The CTS frame time can be denoted as CTS_Time. Or, the response time for an RTS frame or a MU-RTS frame can be denoted as CTS_Time. At this time, the response time for an RTS frame or a MU-RTS frame can mean the length of the PPDU including the response.

[0265] According to one embodiment, the NAV timeout period may be based on at least one of the following.

[0266] 1) CTS_Time

[0267] 2) aSIFSTime

[0268] 3) aRxPHYStartDelay

[0269] 4) aSlotTime

[0270] According to one embodiment, CTS_Time can be calculated based on a previously set ratio (rate). That is, CTS_Time may be the length of the CTS frame calculated based on a previously set ratio. Or, that is, CTS_Time may be the length of the PPDU including the CTS frame calculated based on a previously set ratio. For example, the previously set ratio may be 6 Mbps. For example, CTS_Time can be calculated based on a data rate of 6 Mbps. Or, the previously set rate may be the ratio of the RTS frame or the MU-RTS frame that sets the NAV. Or, the previously set rate may be the ratio indicated by the RTS frame or the MU-RTS frame that sets the NAV.

[0271] According to one embodiment, aSIFSTime may be the SIFS length. For example, aSIFSTime may be 10 us when operating in the 2.4 GHz band. For example, aSIFSTime may be 16 us when operating in the 5 GHz band or 6 GHz band.

[0272] According to one embodiment, aRxPHYStartDelay may be the delay from the start of the PPDU until the receiver generates a PHY-RXSTART.indication primitive. For example, aRxPHYStartDelay may be the time taken to determine the PPDU format from the start of the PPDU. For example, aRxPHYStartDelay may vary depending on the PPDU format. aRxPHYStartDelay may be 20 us for a non-HT PPDU. Also, aRxPHYStartDelay may be 28 us for an HT PPDU in HT-mixed format. Also, aRxPHYStartDelay may be 24 us for an HT PPDU in HT-greenfield format. Also, aRxPHYStartDelay may be (36 + 4*(the maximum possible value for N_VHT-LTF supported) + 4) us for a VHT PPDU. N_VHT-LTF may be the number of VHT-LTFs. Also, aRxPHYStartDelay may be 32 us for a HE SU PPDU or a HE TB PPDU. Also, aRxPHYStartDelay may be 40 us for a HE ER SU PPDU. Also, aRxPHYStartDelay may be (32 + 4*N_HE-SIG-B) us for a HE MU PPDU. N_HE-SIG-B may be the number of OFDM symbols in the HE-SIG-B field. Also, aRxPHYStartDelay may be 32 us for an EHT MU PPDU or an EHT TB PPDU.

[0273] According to one embodiment, the NAV timeout period may be ((2*aSIFSTime)+(CTS_Time)+aRxPHYStartDelay+(2*aSlotTime)).

[0274] According to an embodiment of the present invention, the RTS frame may be a frame that indicates a CTS frame. Alternatively, the RTS frame may be a frame that indicates a CTS frame from a single STA. The RTS frame may include a frame Control field, a Duration field, an RA field, a TA field, and an FCS field. The Duration field may include time information for a STA that receives the Duration field to set the NAV. Also, the RA field may include the address of an intended immediate recipient. For example, when the RA field included in the RTS frame received by the STA is the address of the STA, it is possible to respond with a CTS frame to the RTS frame. Also, whether a frame is an RTS frame may be determined based on the frame Control field included in the frame. For example, whether a frame is an RTS frame may be determined based on the Type subfield and the Subtype subfield included in the frame Control field included in the frame. For example, when the Type subfield is 01 (B3 B2) and the Subtype subfield is 1011 (B7 B6 B5 B4), it can be indicated that a frame including the Type subfield and the Subtype subfield is an RTS frame. For example, the RTS frame may be a Control frame.

[0275] The CTS frame may include a frame control field, a duration field, an RA field, and an FCS field. The duration field may include time information for a STA that receives the duration field to set the NAV. For example, when the Type subfield is 01 (B3 B2) and the Subtype subfield is 1100 (B7 B6 B5 B4), it can be indicated that a frame including the Type subfield and the Subtype subfield is a CTS frame. For example, the CTS frame may be a control frame.

[0276] Referring to the first sequence in FIG. 23, STA1, STA2, and STA3 may exist. Also, STA1 can send an RTS frame or a MU-RTS frame to STA2. For example, when the RA field of the RTS frame or the MU-RTS frame is set to the address of STA2, the RTS frame or the MU-RTS frame may be sent to STA2. Or, when the User Info field included in the MU-RTS frame indicates STA2, the MU-RTS frame may be sent to STA2. If STA2 successfully receives the RTS frame or the MU-RTS frame, it can respond with a CTS frame. At this time, STA2 can respond based on the carrier sense (CA) result. Also, when STA3 receives the RTS frame or the MU-RTS frame, STA3 can set the NAV based on the duration information included in the RTS frame or the MU-RTS frame or the duration information included in the PPDU including the RTS frame or the MU-RTS frame. Also, when STA1 successfully receives the CTS frame sent by STA2, STA1 can send a frame to STA2. Also, after STA3 sets the NAV, it may receive the CTS frame sent by STA2 or the frame sent by STA1 to STA2. In such a case, STA3 can receive a PHY-RXSTART.indication primitive within the NAVTimeout period. Therefore, the NAV set by STA3 may not be able to be released.

[0277] Referring to the second sequence in FIG. 23, STA1, STA2, and STA3 may exist. Also, STA1 can send an RTS frame or a MU-RTS frame to STA2. If STA2 fails to successfully receive the RTS frame or the MU-RTS frame, it may not be able to respond with a CTS frame. Or, although STA2 successfully receives the RTS frame or the MU-RTS frame, it may not be able to respond with a CTS frame based on the carrier sense result. In such a case, the frame sequence sent by STA1 to STA2 may not continue.

[0278] Also, when STA3 receives the RTS frame or the MU-RTS frame, based on the duration information included in the RTS frame or the MU-RTS frame or the duration information included in the PPDU including the RTS frame or the MU-RTS frame, STA3 can set the NAV. Also, after STA3 sets the NAV, it may not be able to receive the CTS frame sent by STA2 or the frame sent by STA1 to STA2. In such a case, STA3 cannot receive the PHY-RXSTART.indication primitive within the NAVTimeout period. Therefore, STA3 can release the NAV it set. This can solve the problem that STA3 cannot access the channel because it maintains the NAV even though the sequence did not continue.

[0279] FIG. 24 is a diagram showing the sharing of TXOP and the NAV timeout according to an embodiment of the present invention.

[0280] Referring to FIG. 24, as described above, STA1 can perform TXOP sharing with STA2. STA1 may be the STA that performs TXOP sharing, and STA2 may be the STA that receives TXOP sharing. STA1 can transmit the first frame of the sequence to STA2. Referring to FIG. 24, the first frame of the sequence transmitted by STA1 to STA2 may be a MU-RTS frame. Also, a CTS frame, which is a response to the MU-RTS frame, may be transmitted.

[0281] For example, a CTS frame may be transmitted from a STA including STA2. STA1 can obtain a TXOP. Also, STA3 may not be able to successfully receive the MU-RTS frame and the CTS frame. STA1 can transmit a modified MU-RTS frame to STA2. That is, STA1 can perform TXOP sharing with STA2. Also, STA3 can successfully receive the modified MU-RTS frame. Therefore, STA3 can set the NAV based on the modified MU-RTS frame. In this case, STA3 may set the NAV based on the MU-RTS frame. Also, according to the above-described TXOP sharing sequence, for the modified MU-RTS frame, STA2 can: 1) transmit a CTS frame and transmit a frame immediately after transmitting the CTS frame. Or, for the modified MU-RTS frame, STA2 can: 2) not transmit a CTS frame and transmit a frame. Also, STA3 may not be able to receive a frame or PPDU from STA2. For example, STA3 may be located at a hidden position from STA2. For example, the power transmitted by STA2 may not be sufficient to be received by STA3. In such a case, STA3 may not be able to receive a PPDU during the NAV timeout period. This may be because the NAV timeout period is determined based on CTS_Time. That is, when STA2 transmits a frame after transmitting a CTS frame, the NAVTimeout period should end while the frame is being transmitted. Or, when STA2 transmits a frame without transmitting a CTS frame, since the frame is likely to be longer than the CTS frame, the NAVTimeout period should end while the frame is being transmitted. Therefore, STA3 can release the NAV. If STA3 releases the NAV, STA3 may connect to the channel and interfere with the sequence during the shared TXOP.

[0282] FIG. 25 is a diagram showing the sharing of TXOP and NAV timeout according to still another embodiment of the present invention.

[0283] Referring to FIG. 25, when the TXOP is shared by the AP, other STAs (third STAs) that are not the STAs for which the TXOP is shared by the AP do not have to release the shared TXOP even when no CTS frame or other frame is transmitted from the STA for which the TXOP is shared for a certain period of time. The embodiment of FIG. 25 may be for solving the problems described in FIGS. 23 and 24. Also, the above-described content may be omitted.

[0284] Specifically, based on whether the trigger frame (e.g., MU-RTS frame) transmitted from the AP is a modified MU-RTS frame or a MU-RTS TXS trigger frame for sharing the TXOP, a NAV timeout for releasing the TXOP may or may not be allowed. That is, depending on whether it is a generally set TXOP or all or part of the TXOP set by the AP is a shared TXOP, it may be determined whether a NAV timeout for releasing the TXOP set by other STAs that are not the STAs for which the TXOP is set is allowed.

[0285] For example, when the NAV is set based on a MU-RTS frame that is not a frame (modifited MU-RTS frame or MU-RTS TXS trigger frame) for sharing part or all of the set TXOP, the NAV timeout may be allowed. That is, when the STA sets the NAV based on the MU-RTS frame, when the MU-RTS frame is not a modified MU-RTS frame, and when the PPDU reception cannot be successfully started during the NAVTimeout period, it is possible to release the NAV.

[0286] However, when the NAV is set by a modified MU-RTS frame or an MU-RTS TXS trigger frame that is a frame for sharing some or all of the set TXOP, the NAV timeout may not be allowed. That is, when a STA sets the NAV based on an MU-RTS frame, if the MU-RTS frame is a modified MU-RTS frame or an MU-RTS TXS trigger frame for TXOP sharing, the STA is not allowed to release the NAV even if it cannot successfully start receiving a PPDU during the NAV timeout period.

[0287] That is, if the frame most recently received by the STA for NAV update is a modified MU-RTS frame or an MU-RTS TXS trigger frame that is a frame for TXOP sharing, the STA shall not reset the NAV after the NAV timeout expires.

[0288] The determination as to whether the received MU-RTS frame is a modified MU-RTS frame can follow the foregoing embodiments. For example, based on the GI And HE-LTF Type subfield included in the MU-RTS frame, it may be determined whether it is a modified MU-RTS frame. For example, when the GI And HE-LTF Type subfield value is 0, the MU-RTS frame including the GI And HE-LTF Type subfield may not be a modified MU-RTS frame. Also, when the GI And HE-LTF Type subfield value is not 0, the MU-RTS frame including the GI And HE-LTF Type subfield may be a modified MU-RTS frame. For example, when the GI And HE-LTF Type subfield value is 1 or 2, the MU-RTS frame including the GI And HE-LTF Type subfield may be a modified MU-RTS frame.

[0289] According to the embodiments of the present invention, it is possible to prevent the problem described with reference to FIG. 24, that is, the problem of interfering with the sequence of shared TXOPs by performing the NAV timeout operation after the STA sets the NAV based on the modified MU-RTS frame.

[0290] In addition, such embodiments may be performed by terminals after the 802.11be standard (including terminals of subsequent standards including the EHT standard), and may not be performed by terminals of the 802.11ax standard (HE STA). Even if the HE STA cannot perform this, the probability of the problem described above occurring can be reduced according to the above embodiments.

[0291] Referring to FIG. 25, STA1, STA2, and STA3 may exist. Also, STA1 can transmit a MU-RTS frame to STA2. For example, STA1 can transmit a MU-RTS frame that is not a modified MU-RTS frame. However, STA2, which is the intended receiver of the MU-RTS frame, may not be able to respond to the MU-RTS frame. Therefore, STA2 may not be able to transmit a CTS frame. Also, STA3 can set the NAV based on the MU-RTS frame. However, since STA2 was unable to transmit a CTS frame, STA3 may not have successfully started receiving the PPDU during the NAVTimeout period. In this case, based on the NAV timeout operation, STA3 can cancel the set NAV. This is because the frame that caused STA3 to set the NAV is a MU-RTS frame that is not a modified MU-RTS frame.

[0292] In addition, STA1 can transmit a modified MU-RTS frame. In FIG. 25, the frame before the modified MU-RTS frame may be omitted. STA2, which is the intended recipient of the modified MU-RTS frame, can respond to the modified MU-RTS frame. Also, STA3 can set the NAV based on the modified MU-RTS frame. However, there may be a case where STA3 fails to receive the response transmitted by STA2 to the modified MU-RTS frame. For example, this is because the response transmitted by STA2 to STA3 cannot be heard at a sufficiently high power. For example, this is because STA3 and STA2 are far apart. In such a case, STA3 may not be able to successfully start receiving the PPDU during the NAVTimeout period. This may be because after STA2 transmitted the CTS frame after the modified MU-RTS frame, it transmitted a frame. Or, this may be because after STA2 transmitted the modified MU-RTS frame, it transmitted a frame longer than the CTS frame. Or, this may be because after STA2 transmitted the modified MU-RTS frame, it transmitted a PPDU longer than the PPDU including the CTS frame. In this case, STA3 may not be able to perform the operation of releasing the NAV based on the NAV timeout operation. This may be because the frame that caused STA3 to set the NAV is the MU-RTS frame, which is the modified MU-RTS frame.

[0293] FIG. 26 is a diagram showing the sharing of TXOP and NAV timeout according to still another embodiment of the present invention.

[0294] The embodiment of FIG. 26 may be for solving the problems described in FIGS. 23 and 24. Also, the above-described content may be omitted.

[0295] According to an embodiment of the present invention, the NAV timeout period may be determined individually based on whether the MU-RTS frame is a modified MU-RTS frame. For example, the CTS_Time may be determined individually based on whether the MU-RTS frame is a modified MU-RTS frame. According to an embodiment, when the MU-RTS frame is a modified MU-RTS frame, the NAV timeout period may be longer than the NAV timeout period when the MU-RTS frame is not a modified MU-RTS frame. In this embodiment, when the MU-RTS frame is a modified MU-RTS frame, the NAV timeout period can be called the extended NAVTimeout period. The NAVTimeout period and the extended NAVTimeout period described in FIG. 23 may start at the same time. That is, it may start when the PHY-RXEND.indication primitive corresponding to the MU-RTS frame is received. The NAVTimeout period described in FIG. 23 may be a time based on the CTS frame time. For example, the NAVTimeout period described in FIG. 23 may be a time based on the time it takes to transmit the CTS frame at 6 Mbps.

[0296] According to an embodiment of the present invention, when the STA sets the NAV based on the modified MU-RTS frame, if the PPDU reception cannot be successfully started during the extended NAVTimeout period, the NAV can be released. When the STA sets the NAV based on the modified MU-RTS frame, there may be a case where the NAV cannot be released even if the PPDU reception cannot be successfully started during the NAVTimeout period described in FIG. 23.

[0297] Also, when the STA sets the NAV based on a MU-RTS frame that is not a modified MU-RTS frame, and fails to successfully start receiving the PPDU during the NAVTimeout period described in FIG. 23, it is possible to release the NAV.

[0298] According to an embodiment of the present invention, the extended NAVTimeout period may be determined based on the length information included in the modified MU-RTS frame. For example, the CTS_Time may be determined based on the length information included in the modified MU-RTS frame. Alternatively, the extended NAVTimeout period may be determined based on the length information included in the modified MU-RTS frame and the rate corresponding to the modified MU-RTS frame. For example, the CTS_Time may be determined based on the length information included in the modified MU-RTS frame and the rate corresponding to the modified MU-RTS frame. For example, the length information included in the modified MU-RTS frame may be included in the UL Length subfield shown in FIG. 16. In yet another embodiment, the length information included in the modified MU-RTS frame may be included in the User Info field shown in FIG. 16. More specifically, the length information included in the modified MU-RTS frame may be included in the User Info field that indicates the STA receiving the TXOP sharing among the User Info fields shown in FIG. 16.

[0299] Also, the STA that has received the TXOP sharing can transmit a PPDU based on the length information included in the modified MU-RTS frame. For example, the STA that has received the TXOP sharing can transmit the first PPDU of the shared TXOP based on the length information included in the modified MU-RTS frame. Or, the STA that has received the TXOP sharing can transmit the first PPDU that does not include the CTS frame of the shared TXOP based on the length information included in the modified MU-RTS frame. The first PPDU that does not include the CTS frame of the shared TXOP may be the first PPDU after the PPDU that includes the CTS frame.

[0300] Referring to FIG. 26, STA1, STA2, and STA3 may exist. Also, STA1 can transmit a MU-RTS frame to STA2. For example, STA1 can transmit a MU-RTS frame that is not a modified MU-RTS frame. However, STA2, which is the intended recipient of the MU-RTS frame, may not be able to respond to the MU-RTS frame. Therefore, STA2 may not be able to transmit a CTS frame. Also, STA3 can set the NAV based on the MU-RTS frame. However, since STA2 was unable to transmit a CTS frame, STA3 may not be able to successfully start receiving a PPDU during the NAV timeout period. In this case, based on the NAV timeout operation, STA3 can release the set NAV. This may be an operation based on the determined NAV timeout period because the frame that caused STA3 to set the NAV is a MU-RTS frame that is not a modified MU-RTS frame. That is, since the frame that caused STA3 to set the NAV is a MU-RTS frame that is not a modified MU-RTS frame, the NAV timeout period can be determined based on the time it takes to transmit a CTS frame.

[0301] In addition, STA1 can transmit a modified MU-RTS frame. FIG. 26 may omit the frame before the modified MU-RTS frame. STA2, which is the intended recipient of the modified MU-RTS frame, can respond to the modified MU-RTS frame. Also, STA3 can set the NAV based on the modified MU-RTS frame. However, there may be a situation where STA3 cannot receive the response sent by STA2 to the modified MU-RTS frame. For example, it may be because the response sent by STA2 to STA3 cannot be heard at a sufficiently high power. For example, it may be because STA3 and STA2 are far apart. In such a case, STA3 may not be able to successfully start receiving the PPDU during the NAVTimeout period described in FIG. 23. However, in such a case, STA3 can successfully start receiving the PPDU during the extended NAVTimeout period. Therefore, STA3 does not have to perform the NAV timeout operation. The reason why STA3 can wait for the extended NAVTimeout period without performing the NAV release operation when the NAVTimeout period described in FIG. 23 has passed may be that the frame for which STA3 sets the NAV is a MU-RTS frame which is a modified MU-RTS frame.

[0302] If STA2, which has received the modified MU-RTS frame, is unable to respond, STA1 can perform a recovery operation. Therefore, STA3 can successfully start receiving the PPDU before performing the NAV timeout operation.

[0303] Alternatively, when STA2 that has received the modified MU-RTS frame fails to respond, the sequence of the shared TXOP may end. In this case, STA3 can perform a NAV timeout operation to solve the problem that the NAV is set unnecessarily when no actual frame exchange occurs and the channel cannot be connected.

[0304] In TXOP sharing, the problem that it is difficult for a scheduled STA that shares some or all of the TXOP set by the AP to transmit due to the set NAV and the solution method were described with reference to FIG. 20. Further, the solution method according to another embodiment will be described with reference to FIG. 27. Hereinafter, the scheduled STA and the STA that shares the TXOP are the same STA, and the names may be used interchangeably.

[0305] FIG. 27 is a diagram showing that the STA and the AP apply the NAV when TXOP sharing is applied according to an embodiment of the present invention.

[0306] In TXOP sharing, a scheduled STA does not have to set the NAV. Specifically, in TXOP sharing, a scheduled STA does not have to set the NAV based on a modified MU-RTS frame or an MU-RTS TXS trigger frame that is an MU-RTS frame for TXOP sharing settings. A STA that receives an MU-RTS frame for TXOP sharing settings does not have to set the NAV based on the MU-RTS frame for TXOP sharing settings. A STA scheduled by an MU-RTS frame for TXOP sharing settings does not have to set the NAV based on the MU-RTS frame for TXOP sharing settings. Therefore, when a STA receives a trigger frame and the trigger frame schedules TXOP sharing for the STA, the STA does not have to set the NAV based on the trigger frame. That is, depending on whether the trigger frame is a trigger frame for sharing TXOP, the STA can set the NAV based on the received trigger frame. For example, when the received MU-RTS frame is a modified MU-RTS frame or an MU-RTS TXS trigger frame for sharing TXOP, the STA does not set the NAV based on the received MU-RTS frame. However, when the received MU-RTS frame is not a modified MU-RTS frame or an MU-RTS TXS trigger frame for sharing TXOP, the STA sets the NAV based on the received MU-RTS frame.

[0307] Also, in TXOP sharing, a scheduled STA does not have to set the NAV based on the frames received within the shared TXOP.

[0308] At this time, within the shared TXOP, even if the duration of the shared TXOP is not fully utilized, it can refer to the time until the shared TXOP ends. When the scheduled STA of the shared TXOP transmits a PPDU that includes only frames that do not require an immediate response, the TXOP ends when the STA transmits the PPDU. Therefore, within the shared TXOP, it can be from when TXOP sharing is set until the scheduled STA of TXOP sharing transmits a PPDU that includes only frames that do not require an immediate response. When the scheduled STA of TXOP sharing signals the end of the shared TXOP, the shared TXOP may end. Therefore, within the shared TXOP, it can be from when TXOP sharing is set until the scheduled STA of TXOP sharing signals the end of the shared TXOP. Also, within the TXOP, it can be from when TXOP sharing is set until the duration of the shared TXOP has elapsed. Or, when the STA that received TXOP sharing (or the STA that shared TXOP) transmits and receives signaling indicating that the shared TXOP has ended, the shared TXOP may end. In this case, the duration of the shared TXOP and the TXOP used by the AP for sharing (the TXOP obtained by the first frame of the AP) are the same, or the duration of the shared TXOP is shorter than the duration of the TXOP. Therefore, even if the shared TXOP ends, the TXOP does not have to end. That is, when the duration of the shared TXOP and the duration of the TXOP are the same, when the shared TXOP ends, the TXOP also ends, but when the duration of the shared TXOP is shorter than the duration of the TXOP, the TXOP can be maintained even if the shared TXOP ends.

[0309] In yet another specific embodiment, even if the shared TXOP ends before the shared TXOP period, within the shared TXOP period, it can be from when TXOP sharing is set until the duration of the shared TXOP has elapsed.

[0310] As described above, in TXOP sharing, a scheduled STA can transmit a frame regardless of the NAV. That is, when the NAV is set within a TXOP set by the AP (for example, the NAV set by an intra-BSS PPDU), the scheduled STA can transmit a PPDU within the shared TXOP regardless of the set NAV. In other words, a STA that shares a TXOP can transmit a frame while ignoring the NAV set by the frame transmitted by the STA that shared the TXOP within the shared TXOP. At this time, the shared TXOP may end before the period set by the MU-RTS frame. That is, within the shared TXOP, before the period set by the MU-RTS, the STA that shares the TXOP can interrupt the sharing of the TXOP by transmitting signaling for requesting an interruption of the sharing of the TXOP. For example, when all or part of a TXOP is shared from the AP, if a non-AP STA has no PPDU to transmit (or pend), it can transmit signaling for ending the TXOP sharing to the AP to end the sharing of the TXOP and interrupt the sharing of the TXOP. The point in time when the TXOP sharing is interrupted may be either the point in time when the non-AP STA transmits signaling requesting an interruption of the TXOP sharing or the point in time when it receives a response frame to the signaling. At this time, the signaling for TXOP sharing may or may not require an immediate response. Also, in this case, since the TXOP sharing of the non-AP STA is interrupted at a point in time earlier than the period during which the TXOP set by the MU-RTS frame is shared, the non-AP STA can ignore the set NAV only until the point in time when the sharing of the TXOP ends.

[0311] At this time, the STA that has set TXOP sharing can also transmit frames regardless of the NAV. In the embodiment of FIG. 27, the first STA (STA1) transmits a MU-RTS frame for TXOP sharing to the second STA (STA2). At this time, the first STA (STA1) may be an AP. The second STA (STA2) receives the MU-RTS frame for TXOP sharing and transmits a CTS frame as a response to the MU-RTS frame for TXOP sharing. The second STA (STA2) performs frame exchange within the shared TXOP. The first STA (STA1) can set the NAV based on the frames transmitted by the second STA (STA2) or the frames transmitted to the second STA (STA2). For example, within the shared TXOP, the second STA (STA2) can perform frame exchange with the third STA (STA3). At this time, the first STA (STA1) can set the NAV based on the frame transmitted by the third STA (STA3) to the second STA (STA2). Also, the first STA (STA1) can set the NAV based on the frame transmitted by the second STA (STA2) to the third STA (STA3). When the first STA (STA1) sets the NAV in this way, it may be difficult to transmit frames within the TXOP to which the shared TXOP is assigned. For example, when the first STA (STA1) attempts to transmit a frame after the shared TXOP has ended, the frame may not be transmitted due to the NAV set within the shared TXOP. Specifically, when the frame included in the PPDU transmitted within the shared TXOP is not a frame that induces an immediate response from the first STA (STA1), the first STA (STA1) may not be able to transmit the frame due to the set NAV.

[0312] A STA that has set TXOP sharing can transmit frames within the TXOP it has acquired regardless of NAV. Further, in other specific embodiments, a STA that has set TXOP sharing can transmit frames within the TXOP it has acquired since the end of the shared TXOP regardless of NAV. A STA that has set TXOP sharing may be the STA that transmitted the MU-RTS frame for setting TXOP sharing or the TXOP holder.

[0313] At this time, as described above, the shared TXOP may end before the interval set by the MU-RTS frame. That is, within the shared TXOP and before the interval set by MU-RTS, the STA that shared the TXOP can interrupt the sharing of the TXOP by transmitting signaling for requesting interruption of the sharing of the TXOP. For example, when all or part of the TXOP is shared from the AP, if there is no PPDU to be transmitted (or pending) by the non-AP STA, the non-AP STA can transmit signaling for ending the sharing of the TXOP to the AP to interrupt the sharing of the TXOP in order to end the shared TXOP. The point in time when the TXOP sharing is interrupted may be either the point in time when the non-AP STA transmits the signaling requesting interruption of the TXOP sharing or the point in time when it receives the response frame to the signaling. At this time, the signaling for TXOP sharing may or may not require an immediate response. Also, in this case, since the TXOP sharing is interrupted earlier than the interval during which the TXOP set by the MU-RTS frame is shared, from the point in time when the sharing of the TXOP ends, the AP can ignore the NAV set by the AP based on the PPDUs transmitted and received by the non-AP STA.

[0314] In the foregoing embodiments, the fact that the STA that has set TXOP sharing transmits a frame regardless of the NAV can represent that the STA transmits a frame regardless of the NAV set based on the frames exchanged by the scheduled STAs within the TXOP sharing. This is because, when the STA that has set TXOP sharing transmits a frame regardless of the NAV set based on the frames that the scheduled STAs within the TXOP sharing did not exchange, it may interfere with the frame exchanges of other STAs. Also, the STA can determine whether a frame is a frame exchanged by the scheduled STAs within the TXOP sharing based on the MAC header of the frame. Specifically, the STA can determine whether a frame is a frame exchanged by the scheduled STAs within the TXOP sharing based on the address field of the frame. The address field may include at least any one of the RA field, the TA field, and the BSSID field. For example, when one of the fields in the address field of the frame indicates the MAC address of the STA, the STA can determine that the frame is a frame exchanged by the scheduled STAs within the TXOP sharing. Also, the STA can determine whether a frame is a frame exchanged by the scheduled STAs within the TXOP sharing based on the preamble of the PPDU including the frame. Also, the STA can determine whether a frame is a frame exchanged by the scheduled STAs within the TXOP sharing based on at least any one of the BSS color and the STA ID included in the preamble of the PPDU including the frame. When the preamble of the PPDU includes the BSS color of the BSS to which the scheduled STA of the TXOP sharing belongs and the preamble of the PPDU includes the STA ID corresponding to the scheduled STA of the TXOP sharing, the STA can determine that the frame included in the PPDU is a frame exchanged by the scheduled STA. At this time, the STA ID may be a value set based on the AID of the STA.

[0315] In yet another specific embodiment, when a STA that has set TXOP sharing transmits regardless of the NAV, only physical CS such as CCA can be used as carrier sensing (CS) when transmitting a frame. Therefore, the STA does not have to perform virtual CS.

[0316] In this specification, setting the NAV may be used interchangeably with updating the NAV. Also, in this specification, the NAV may include at least one of Intra-BSS NAV or basic NAV. Also, when there is no particular mention of the type of NAV, the NAV may refer to Intra-BSS NAV. Also, in this specification, when a STA sets the NAV based on any frame, it may include setting the NAV based on the PPDU including the frame. Therefore, in this specification, when a STA does not set the NAV based on any frame, it may include not setting the NAV based on the PPDU including the frame.

[0317] The MU-RTS frame for setting TXOP sharing can indicate the scheduled STA of the TXOP using a MAC address, for example, the RA field or the User Info field. Setting the NAV based on the duration information of the frame or PPDU can indicate that the most recently set NAV is set based on the duration information of the frame or PPDU.

[0318] In yet another specific embodiment, the Duration / ID field of the frame transmitted within the shared TXOP or the TXOP of the PPDU including the frame may be set based on the shared TXOP. Specifically, the Duration / ID field of the frame transmitted within the shared TXOP or the TXOP of the PPDU including the frame may not be allowed to be set beyond the shared TXOP. Thereby, it is possible to prevent the problem that the STA that set the shared TXOP cannot transmit a frame even after the end of the shared TXOP.

[0319] That is, when the TXOP set by the AP is shared with the STA by the trigger frame, the duration information (for example, Duration / ID field) included in the frame (for example, PPDU) transmitted within the shared TXOP may be set based on the shared TXOP. Specifically, the TXOP of the frame transmitted within the shared TXOP is not allowed to be set beyond the shared TXOP. Therefore, the TXOP of the PPDU transmitted to the AP or the third STA for P2P communication that set the TXOP within the shared TXOP must be the same as or end earlier than the shared TXOP. Therefore, the end time of the duration indicated by the duration information included in the PPDU may be the same as or earlier than the end time of the shared TXOP. In other words, when part or all of the TXOP set by the AP is shared with a specific STA, the TXOP of the PPDU transmitted by the specific STA must not exceed the shared TXOP and must end earlier. Therefore, the end time of the length (or, TXOP) of the PPDU transmitted by the specific STA to the AP or the third STA for P2P communication must not be after the end time of the shared TXOP and must be earlier. In this case, the end time of the length (or, TXOP) of the PPDU must be the same as or earlier than the end time of the shared TXOP, and thus, the value indicated by the duration information included in the PPDU may be set based on the shared TXOP.

[0320] In yet another specific embodiment, the STA that sets the shared TXOP may not need to set the NAV based on the frames exchanged by the scheduled STA for TXOP sharing.

[0321] The STA that sets the shared TXOP within the shared TXOP may not need to transmit a trigger frame. This is because when the STA that sets the shared TXOP within the shared TXOP transmits a trigger frame, the frame exchange between the frame triggered by the trigger frame and the frame of the scheduled STA may overlap. Also, when the STA that sets the shared TXOP within the shared TXOP transmits a trigger frame to the scheduled STA, the scheduled STA may have to transmit a response to the trigger frame. Therefore, this may not conform to the purpose of setting the shared TXOP. In such an embodiment, the trigger frame may include a MU-RTS frame for setting TXOP sharing. In such an embodiment, after the shared TXOP ends, the STA that set the shared TXOP can transmit a trigger frame.

[0322] In the foregoing embodiments, the trigger frame that a STA having set a shared TXOP cannot transmit may be the remaining trigger frames other than the trigger frame only for the scheduled STA of TXOP sharing. Therefore, a STA having set a shared TXOP can transmit a trigger frame only to the scheduled STA of TXOP sharing within the shared TXOP. For example, a STA having set a shared TXOP can transmit a MU-RTS frame for setting TXOP sharing to extend the shared TXOP. At this time, a STA that has received the MU-RTS frame for setting TXOP sharing can start frame exchange without transmitting a CTS frame. Specifically, when only frame exchange with the STA that has set TXOP sharing is allowed in TXOP sharing, a STA that has received the MU-RTS frame for setting TXOP sharing can start frame exchange without transmitting a CTS frame.

[0323] In this specification, the operations performed during a shared TXOP may be operations in which the shared TXOP is utilized by the scheduled STA of TXOP sharing. The operations performed during a shared TXOP may be transmitting a frame as a response to a MU-RTS frame for setting TXOP sharing by the scheduled STA of TXOP sharing, or transmitting a frame within the shared TXOP by the scheduled STA of TXOP sharing. At this time, the response frame to the MU-RTS frame for setting TXOP sharing may be a CTS frame.

[0324] Describe the signaling for TXOP co-operative operations. A STA can signal whether it can operate as a scheduled STA for TXOP sharing. At this time, the STA can signal whether it can operate as a scheduled STA for TXOP sharing using the EHT Capabilities element. Also, the STA can send signaling indicating whether it can operate as a scheduled STA for TXOP sharing using a (re)association request frame or a probe request frame. A STA attempting to configure TXOP sharing can send a MU-RTS frame for configuring TXOP sharing only to a STA that has signaled that it can operate as a scheduled STA for TXOP sharing. Also, a STA attempting to configure TXOP sharing does not have to send a MU-RTS frame for configuring TXOP sharing to a STA that has signaled that it cannot operate as a scheduled STA for TXOP sharing.

[0325] In addition, the MU-RTS frame may include information indicating whether the MU-RTS frame is an MU-RTS frame for setting TXOP sharing. Also, when the MU-RTS frame is an MU-RTS frame for setting TXOP sharing, the MU-RTS frame can also indicate the mode of TXOP sharing. The mode of TXOP sharing can indicate which STA the scheduled STA for TXOP sharing can send frames to. For example, in the first mode, the scheduled STA for TXOP sharing can send frames only to the STA that set TXOP sharing. Also, in the second mode, the scheduled STA for TXOP sharing can send frames to the STA that set TXOP sharing or send P2P frames. When the value of the information indicating whether the MU-RTS frame is an MU-RTS frame for setting TXOP sharing is 1, the first mode can be indicated. Also, when the value of the information indicating whether the MU-RTS frame is an MU-RTS frame for setting TXOP sharing is 2, the second mode can be indicated. Also, when the value of the information indicating whether the MU-RTS frame is an MU-RTS frame for setting TXOP sharing is 0, it can be indicated that the MU-RTS frame is not an MU-RTS frame for setting TXOP sharing.

[0326] In these embodiments, the GI And HE-LTF Type subfield can indicate whether the MU-RTS frame is an MU-RTS frame for setting TXOP sharing. When the MU-RTS frame is an MU-RTS frame for setting TXOP sharing, the GI And HE-LTF Type subfield can indicate the mode of TXOP sharing as described above. At this time, the GI And HE-LTF Type subfield can be called the TXOP Sharing Mode subfield. The TXOP Sharing Mode subfield may be a subfield from the 21st bit (B20) to the 22nd bit (B21) of the Common Info field in FIG. 16.

[0327] A method for ending TXOP sharing will be described with reference to FIG. 28.

[0328] FIG. 28 is a diagram showing that a STA ends TXOP sharing according to an embodiment of the present invention.

[0329] The scheduled STA for TXOP sharing can signal the end of TXOP sharing. When the STA that has set TXOP sharing receives the end signaling of TXOP sharing, the STA that has set TXOP sharing can become the TXOP holder. Also, when the STA that has set TXOP sharing receives the end signaling of TXOP sharing, the STA that has set TXOP sharing can transmit a frame or PPDU. Specifically, when the STA that has set TXOP sharing receives the end signaling of TXOP sharing, even within the shared TXOP, the STA that has set TXOP sharing can transmit a frame or PPDU. Also, when the scheduled STA for TXOP sharing signals the end of TXOP sharing, the scheduled STA for TXOP sharing does not have to be able to transmit any frames or PPDUs within the remaining shared TXOP.

[0330] The scheduled STA for TXOP sharing can signal the end of TXOP sharing using the A-Control subfield. Specifically, the SRS (single response scheduling) Control subfield of the A-Control subfield can signal the end of TXOP sharing. The STA that has received the SRS Control subfield can respond to the frame including the SRS Control subfield with a PPDU that is not a TB PPDU. Also, the length of the response PPDU to the frame including the SRS Control subfield may be determined based on the SRS Control subfield. Specifically, the STA that has received the SRS Control subfield can set the length of the response PPDU to the frame including the SRS Control subfield to the length indicated by the SRS Control subfield.

[0331] Figure 28(a) shows the format of the SRS Control subfield. As described above, the SRS Control subfield may include a field that indicates the length of the PPDU that is a response to the MAC frame including the SRS Control subfield. At this time, the field can be called the PPDU Response Duration field. The PPDU Response Duration field can indicate time in units of 4 us. The length of the PPDU indicated by the PPDU Response Duration field may be the value of the PPDU Response Duration field × 4 us. Also, the PPDU Response Duration field may be an 8-bit field.

[0332] Also, the STA can signal its capability with respect to the SRS Control subfield. Specifically, the STA can signal whether it can receive the SRS Control subfield. Also, the STA can signal whether it can respond to a frame including the SRS Control subfield. The STA cannot transmit the SRS Control subfield to a STA that signals that it does not support the operation with respect to the SRS Control subfield. The STA can transmit the SRS Control subfield to a STA that signals that it supports the operation with respect to the SRS Control subfield.

[0333] Also, the SRS Control field may include a field that signals the end of TXOP sharing. The field that signals the end of TXOP sharing can be called the Shared TXOP Termination field. The Shared TXOP Termination field may be a 1-bit field. When the value of the Shared TXOP Termination field is 1, the Shared TXOP Termination field can indicate that the TXOP sharing ends. When the value of the Shared TXOP Termination field is 0, the Shared TXOP Termination field can indicate that the TXOP sharing does not end. When the STA receives a QoS Data frame or a QoS Null frame in which the value of the Shared TXOP Termination field is 1, the STA can determine that the TXOP sharing ends.

[0334] In still other specific embodiments, a frame having a specified setting can signal the end of TXOP sharing. At this time, the frame having the specified setting may be a Qos Null frame. Specifically, the frame having the specified setting may be a QoS Null frame that does not include an A-Control subfield. Also, the frame having the specified setting may be a QoS Null frame that does not include an SRS Control subfield. The scheduled STA for TXOP sharing can transmit a frame having the specified setting to signal the end of TXOP sharing. Also, when the STA that sets the TXOP sharing receives a frame having the specified setting, the STA that sets the TXOP sharing can determine that the TXOP sharing ends.

[0335] Although the scheduled STA sharing the TXOP has sent the termination signaling of the TXOP sharing, the STA that has set up the TXOP sharing may not be able to receive the signaling. At this time, the scheduled STA sharing the TXOP determines that the TXOP sharing has ended and does not have to send a frame. Also, the STA that has set up the TXOP sharing determines that the TXOP sharing has not ended and does not have to send a frame.

[0336] In a specific embodiment, when the scheduled STA of TXOP sharing that signaled the end of TXOP sharing receives a response to the signaling, the scheduled STA of TXOP sharing can determine that the TXOP sharing has ended. At this time, the scheduled STA of TXOP sharing determines that the TXOP sharing has ended and does not need to transmit a frame. The response to the end signaling of TXOP sharing may be an immediate response. Also, the response to the end signaling of TXOP sharing may be an ACK. However, such an embodiment may be applicable only when the Ack policy of the end signaling of TXOP sharing is set to require an immediate response. Specifically, when the Ack policy of the end signaling of TXOP sharing requires an immediate response, when the scheduled STA of TXOP sharing that signaled the end of TXOP sharing receives a response to the signaling, the scheduled STA of TXOP sharing can determine that the TXOP sharing has ended. When the Ack policy of the end signaling of TXOP sharing does not require an immediate response, for example, No ACK, even if the scheduled STA of TXOP sharing that signaled the end of TXOP sharing does not receive a response to the signaling, the scheduled STA of TXOP sharing can determine that the TXOP sharing has ended. At this time, when the scheduled STA of TXOP sharing transmits the end signaling of TXOP sharing, it can determine that the TXOP sharing has ended. Also, when the transmission of the end signaling of TXOP sharing fails, an error recovery operation may be performed. Specifically, the scheduled STA of TXOP sharing can perform an error recovery operation. Also, the STA that set the TXOP sharing can perform an error recovery operation.

[0337] In Fig. 28(b), the first STA (STA1) transmits a MU-RTS frame for TXOP sharing setting to the second STA (STA2). At this time, the first STA (STA1) may be an AP. The second STA (STA2) receives the MU-RTS frame for TXOP sharing setting and transmits a CTS frame as a response to the MU-RTS frame for TXOP sharing setting. Within the shared TXOP, the second STA (STA2) transmits a TXOP sharing termination signaling (Frame to STA1 indicating termination) to the first STA (STA1). The first STA (STA1) fails to receive the TXOP sharing termination signaling (Frame to STA1 indicating termination). At this time, the first STA (STA1) determines that the TXOP sharing has not ended. As described above, the first STA (STA1) or the second STA (STA2) can perform an error recovery operation. After the error recovery operation, the second STA (STA2) transmits a TXOP sharing termination signaling (Frame to STA1 indicating termination) to the first STA (STA1). The first STA (STA1) transmits an ACK (Ack to STA2) which is a response to the TXOP sharing termination signaling (Frame to STA1 indicating termination) to the second STA (STA2). The second STA (STA2) that has received the ACK (Ack to STA2) determines that the TXOP sharing has ended.

[0338] Even after the TXOP sharing has ended, when the STA that set the TXOP sharing instructs a response, the scheduled STA for TXOP sharing can transmit a frame.

[0339] As described above, an STA that signals that it does not support operations on the SRS Control subfield may not be required to transmit the SRS Control subfield. When the end of TXOP sharing is signaled in the SRS Control subfield, an STA that signals that it does not support operations on the SRS Control subfield may not be required to receive the end-of-TXOP-sharing signaling. Therefore, the scheduled STA for TXOP sharing can also transmit an SRS Control subfield that signals the end of TXOP sharing to an STA that signals that it does not support operations on the SRS Control subfield. The SRS Control subfield that signals the end of TXOP sharing may be an SRS Control subfield in which the value of the TXOP Termination subfield is 1. The scheduled STA for TXOP sharing cannot transmit an SRS Control subfield in which the value of the TXOP Termination subfield is 0 to an STA that signals that it does not support operations on the SRS Control subfield. Also, the restriction that an STA that signals that it does not support operations on the SRS Control subfield cannot transmit the SRS Control subfield may apply only when the SRS Control subfield is transmitted outside the shared TXOP.

[0340] When the SRS Control subfield signals the end of TXOP sharing, the PPDU Response Duration subfield may be set as a reserved field. All bits of the reserved field may be set to 0. When the SRS Control subfield does not signal the end of TXOP sharing, the PPDU Response Duration subfield can indicate the length of the PPDU that includes a frame that is a response to a frame that includes the SRS Control subfield.

[0341] When the SRS Control subfield signals the end of TXOP sharing, the STA that receives the SRS Control subfield does not have to send a response to the frame containing the SRS Control subfield. Further, in other specific embodiments, when the SRS Control subfield signals the end of TXOP sharing, the STA that receives the SRS Control subfield can send a response to the frame containing the SRS Control subfield regardless of the information signaled by the SRS Control field. At this time, the STA that receives the SRS Control subfield can send a response PPDU regardless of the length of the response PPDU to the frame containing the SRS Control subfield signaled by the SRS Control subfield.

[0342] A STA that receives an SRS Control subfield within a shared TXOP does not have to send a response to the frame containing the SRS Control subfield. Further, in other specific embodiments, a STA that receives an SRS Control subfield within a shared TXOP can send a response to the frame containing the SRS Control subfield regardless of the information signaled by the SRS Control field. At this time, the STA that receives the SRS Control subfield can send a response PPDU regardless of the length of the response PPDU to the frame containing the SRS Control subfield signaled by the SRS Control subfield.

[0343] Alternatively, a STA that receives an SRS Control subfield within a shared TXOP may not respond based on the duration information (PPDU Response Duration subfield value) included in the SRS Control subfield. For example, a STA that receives an SRS Control subfield within a shared TXOP can respond regardless of the duration information (PPDU Response Duration subfield value) included in the SRS Control subfield.

[0344] According to an embodiment of the present invention, the modified MU-RTS frame does not have to be the first frame within the TXOP. For example, the TXOP holder may transmit other frames instead of transmitting the modified MU-RTS frame to obtain the TXOP. Thereby, a STA can set the NAV before setting the NAV based on the modified MU-RTS frame. That is, the STA can set the NAV based on a frame transmitted earlier than the modified MU-RTS frame in the TXOP. The above-described NAV timeout operation can be performed when the NAV is set based on an RTS frame or a MU-RTS frame. However, by causing frame transmission to exist earlier than the modified MU-RTS frame in the TXOP, it is possible to reduce the occurrence of the NAV being set based on an RTS frame or a MU-RTS frame. Also, the duration information included in the modified MU-RTS frame does not have to increase the TXOP.

[0345] FIG. 29 is a flowchart showing an example of the operation of a STA according to an embodiment of the present invention.

[0346] Referring to FIG. 29, a STA may share part or all of the TXOP from an AP, and based on this, can transmit a PPDU within the shared TXOP.

[0347] Specifically, the STA can receive a trigger frame for instructing uplink transmission from an AP (Access Point) (S29010). At this time, the trigger frame may be used to share part or all of the transmission opportunity (TXOP) acquired by the AP with the STA. When it is used for sharing part of the TXOP, it can be called a modified MU-RTS frame or a MU-RTS TXS trigger frame. At this time, the STA can recognize whether the received frame is a frame for sharing the TXOP from the type field of the trigger frame described above.

[0348] After that, the STA can transmit a PPDU to the AP and / or other STAs within the shared TXOP based on the trigger frame (S29020). The PPDU includes duration information indicating the TXOP for transmitting the PPDU, and the duration information may be set based on the shared TXOP.

[0349] The end point of the duration indicated by the duration information may be the same as the end point of the shared TXOP or may end earlier.

[0350] When a NAV (network allocation vector) is set by a frame transmitted by the AP within the TXOP, the PPDU is transmitted regardless of the set NAV within the shared TXOP.

[0351] Furthermore, when a NAV timeout period indicating the NAV and the end time of the NAV is set within the shared TXOP based on the trigger frame by another STA, even if the NAV timeout period expires within the shared TXOP, the NAV set by the other STA within the shared TXOP does not have to be released by the expiration of the NAV timeout period.

[0352] The trigger frame includes a subfield indicating whether the TXOP is shared by the trigger frame.

[0353] When the subfield indicates sharing of the TXOP, the value of the subfield indicates whether communication with the other STA is possible within the shared TXOP.

[0354] The trigger frame includes a type field indicating the type of the trigger frame, and sharing of part or all of the TXOP is set according to the type of the trigger frame indicated by the type field.

[0355] The above description of the present invention is for illustrative purposes, and those with ordinary knowledge in the technical field to which the present invention pertains can easily understand that it can be easily transformed into other specific forms without changing the technical idea and essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative and non-limiting in any aspect. For example, each component described as a single type may be implemented dispersedly, and similarly, components described as being dispersed may also be implemented in a combined form.

[0356] The scope of the present invention is indicated by the claims described below rather than the above detailed description, and any changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention.

Description of Reference Numerals

[0357] 100 Station 110 Processor 120 Communication Unit 140 User Interface Unit 150 Display Unit 160 Memory 210 Processor 220 Communication Unit 260 Memory 300 Server

Claims

1. A station (STA) in a wireless communication system, comprising: a transceiver; and a processor for controlling the transceiver, wherein the processor: receives a trigger frame from an AP (Access Point); the trigger frame is used to share a specific time that is part of or all of a transmission opportunity (TXOP) obtained by the AP with the STA; transmits a frame to the AP and / or another STA within the specific time based on the trigger frame; when an intra-BSS (basic service set) NAV (network allocation vector) is set for the frame, the frame is transmitted within the specific time regardless of the intra-BSS NAV; a STA in which, when a NAV timeout indicating the end of the NAV and the NAV are set based on the trigger frame, the NAV is not released even after the NAV timeout expires within the specific time.

2. The frame includes duration information, wherein the duration information is set based on the specific time, the STA according to Claim 1.

3. The end time indicated by the duration information is not later than the end time of the specific time, the STA according to Claim 2.

4. The processor further: transmits the specific frame that is the last frame transmitted by the STA within the specific time; when the specific frame is transmitted, the specific time is returned to the AP; the STA performs transmission regardless of the intra-BSS NAV until the specific time is returned, the STA according to Claim 1.

5. The trigger frame includes a specific subfield indicating whether the TXOP is shared by the trigger frame, the STA according to Claim 1.

6. When the specific subfield indicates sharing of the TXOP, the value of the specific subfield indicates whether transmission and reception are possible with the AP and / or the other STA within the specific time, the STA according to Claim 5.

7. The trigger frame includes a type field indicating the type of the trigger frame, The STA according to claim 1, wherein the specific time is configured to share part or all of the TXOP based on the type of the trigger frame indicated by the type field.

8. A method for a station (STA) to transmit a frame in a wireless communication system, comprising: Receiving a trigger frame for instructing an uplink transmission from an AP (Access Point), wherein the trigger frame is used to share a specific time that is part or all of a transmission opportunity (TXOP) obtained by the AP with the STA; and Transmitting a frame to the AP and / or other STAs within the specific time based on the trigger frame, wherein when an intra-BSS (basic service set) NAV (network allocation vector) is set, the frame is transmitted within the specific time regardless of the intra-BSS NAV; A method, wherein when a NAV timeout indicating the end of the NAV and the NAV is set based on the trigger frame, the NAV is not released even after the NAV timeout expires within the specific time.

9. The frame includes duration information, The method according to claim 8, wherein the duration information is set based on the specific time.

10. The method according to claim 9, wherein an end time indicated by the duration information is not later than an end time of the specific time.

11. The method further includes: Transmitting a specific frame that is the last frame transmitted by the STA within the specific time, When the specific frame is transmitted, The specific time is returned to the AP, The STA performs transmission regardless of the intra-BSS NAV until the specific time is returned.

12. The method according to claim 8, wherein the trigger frame includes a specific subfield indicating whether the TXOP is shared by the trigger frame.

13. The method according to claim 12, wherein when the specific subfield indicates sharing of the TXOP, a value of the specific subfield indicates whether it is possible to transmit and receive with the AP and / or the other STA within the specific time. **Claim 14** The trigger frame includes a type field indicating a type of the trigger frame, The method according to claim 8, wherein the specific time is configured to share a part or all of the TXOP based on the type of the trigger frame indicated by the type field.

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