Wireless communication method using shared TXOP, and wireless communication terminal using the same

Abstract

To provide a wireless communication method using shared TXOP, and a wireless communication terminal using the same.SOLUTION: A station in a wireless communication system is disclosed. The station includes a transceiver and a processor for controlling the transceiver. The processor receives a trigger frame for triggering uplink transmission from an access point (AP), and the trigger frame allocates, to the station, a part of a transmission opportunity (TXOP) acquired by the AP, as a shared TXOP, transmits a CTS frame as a response to the trigger frame, and switches a first enhanced distributed channel access (EDCA) parameter set used for channel access to a second EDCA parameter set based on transmission for the AP within the shared TXOP.SELECTED DRAWING: Figure 33

Description

Technical Field

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

Background Art

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

[0003] Since IEEE (Institute of Electrical and Electronics Engineers) 802.11 supported the initial wireless LAN technology using a 2.4 GHz frequency, various technology standards have been put into practical use or are under development. First, IEEE 802.11b uses a frequency in the 2.4 GHz band and supports a communication speed of up to 11 Mbps. IEEE 802.11a, which was commercialized after IEEE 802.11b, uses a frequency in the 5 GHz band instead of the 2.4 GHz band, reducing the impact on interference compared to the relatively congested 2.4 GHz band frequency, and using OFDM (Orthogonal Frequency Division Multiplexing) technology to improve the communication speed up to 54 Mbps. However, IEEE 802.11a has the disadvantage of a shorter communication distance compared to IEEE 802.11b. And IEEE 802.11g uses a frequency in the 2.4 GHz band 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. IEEE 802.11n aims 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 processing rate (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 diversified, there has been 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 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 a minimum of 1 Gbps, and the maximum single-link speed can be up to a minimum of 500 Mbps. 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, 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 achieve 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.

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] An embodiment of the present invention aims to provide a wireless communication method using a shared TXOP and a wireless communication terminal using the same.

MEANS FOR SOLVING THE PROBLEMS

[0009] A station of a wireless communication system according to an embodiment of the present invention includes a transceiver; and a processor that controls the transceiver. The processor receives a trigger frame for triggering uplink transmission from an AP (Access Point), and the trigger frame allocates a part of a transmission opportunity (TXOP) acquired by the AP to the station as a shared TXOP, transmits a CTS frame as a response to the trigger frame, and switches a first EDCA (enhanced distributed channel access) parameter set used for channel access to a second EDCA parameter set based on transmission to the AP within the shared TXOP.

[0010] The processor can switch the first EDCA parameter set to the second EDCA parameter set when a QoS (quality of service) data frame is successfully transmitted to the AP within the shared TXOP.

[0011] When the processor transmits a QoS data frame in which the shared station requests an immediate response from the AP within the TXOP and receives a response to the QoS data frame requesting the immediate response, the processor can switch the first EDCA parameter set to the second EDCA parameter set.

[0012] When the processor transmits a QoS data frame in which the station does not request an immediate response from the AP within the shared TXOP, the processor can switch the first EDCA parameter set to the second EDCA parameter set.

[0013] The second EDCA parameter set may be used instead of the first EDCA parameter set based on whether UL MU (multiuser) transmission has been successful.

[0014] When a QoS data frame is successfully transmitted to the AP within the shared TXOP, the value of a timer for the remaining duration to which the second EDCA parameter set is applied can be set to a value greater than 0.

[0015] Even if the processor successfully transmits signaling to the AP to deactivate the UL MU transmission operation within the shared TXOP, the processor does not have to set the value of the timer to 0.

[0016] When the processor successfully transmits signaling to the AP to deactivate the shared TXOP operation, the processor can set the value of the timer to 0.

[0017] The operation method of a station in a wireless communication system according to an embodiment of the present invention includes the steps of receiving a trigger frame for triggering uplink transmission from an AP (Access Point), where the trigger frame allocates a part of a transmission opportunity (TXOP) obtained by the AP to the station as a shared TXOP; transmitting a CTS frame as a response to the trigger frame; and switching a first EDCA (enhanced distributed channel access) parameter set used for channel access to a second EDCA parameter set based on transmission to the AP within the shared TXOP.

[0018] The step of switching the first EDCA parameter set used for channel access to the second EDCA parameter set may include the step of switching the first EDCA parameter set to the second EDCA parameter set when the station successfully transmits a QoS (quality of service) data frame to the AP within the shared TXOP.

[0019] The step of switching the first EDCA parameter set to the second EDCA parameter set when the station successfully transmits a QoS data frame to the AP within the shared TXOP may include the step of switching the first EDCA parameter set to the second EDCA parameter set when the station transmits a QoS data frame requiring an immediate response to the AP within the shared TXOP and receives a response to the QoS data frame requiring the immediate response.

[0020] When the station successfully transmits a QoS data frame to the AP within the shared TXOP, the step of switching the first EDCA parameter set to the second EDCA parameter set may include the step of switching the first EDCA parameter set to the second EDCA parameter set when the station transmits a QoS data frame that does not require an immediate response to the AP within the shared TXOP.

[0021] The second EDCA parameter set may be used instead of the first EDCA parameter set based on whether UL MU (multiuser) transmission is successful.

[0022] The step of switching the first EDCA parameter set used for channel access to the second EDCA parameter set may include setting the value of a timer for the remaining duration to which the second EDCA parameter set is applied to a value greater than 0 when a QoS data frame is successfully transmitted to the AP within the shared TXOP.

[0023] The step of setting the value of the timer for the remaining duration to which the second EDCA parameter set is applied to a value greater than 0 may include not setting the value of the timer to 0 even when the station successfully transmits signaling to deactivate the UL MU transmission operation to the AP within the shared TXOP.

[0024] The step of setting the value of the timer for the remaining duration to which the second EDCA parameter set is applied to a value greater than 0 may include setting the value of the timer to 0 when the station successfully transmits signaling to deactivate the shared TXOP operation to the AP.

Advantages of the Invention

[0025] One embodiment of the present invention provides a wireless communication method for efficiently using a shared TXOP and a wireless communication terminal using the same.

Brief Description of the Drawings

[0026]

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Best Mode for Carrying Out the Invention

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

[0028] Throughout the specification, if a certain configuration is said to be "connected" to another configuration, this includes not only the case where it is "directly connected", but also the case where it is "electrically connected" with other components interposed therebetween. Also, if a certain component "includes" a specific component, this means that, unless otherwise stated to the contrary, it may further include other components rather than excluding other components. In addition, the limiting terms "above" or "below" based on a specific threshold value may be appropriately replaced by "exceeding" or "less than" respectively depending on the embodiment.

[0029] Hereinafter, in the present invention, a field and a subfield may be used in the same meaning.

[0030] FIG. 1 is a diagram showing a wireless LAN system according to an embodiment of the present invention.

[0031] The wireless LAN system includes one or more Basic Service Sets (BSSs), where a BSS represents a set of devices that have successfully synchronized and can communicate with each other. Generally, BSSs are classified into infrastructure BSSs and Independent BSSs (IBSSs). FIG. 1 shows an infrastructure BSS among them.

[0032] As shown in FIG. 1, the infrastructure BSSs BSS1 and BSS2 include one or more stations STA1, STA2, STA3, STA4, STA5, access points AP-1 and AP-2 that are stations providing a Distribution Service, and a Distribution System (DS) that connects the plurality of access points AP-1 and AP-2.

[0033] A station (STA) is any device that includes a Medium Access Control (MAC) and a Physical Layer interface to a wireless medium in accordance with the IEEE 802.11 standard. 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 non-AP or AP, or both. A station for wireless communication includes a processor and a communication unit, and may further include a user interface unit, a display unit, etc. depending on the embodiment. The processor generates frames to be transmitted via a wireless network, or processes frames received via the wireless network, and performs various other processes for controlling the station. And the communication unit is functionally connected to the processor and transmits and receives frames via a wireless network for the station. In the present invention, the term "terminal" is used to include user equipment (UE).

[0034] An access point (AP) is an entity that provides a connection to a distribution system DS via a wireless medium for stations associated with itself. In an infrastructure BSS, in principle, communication between non-AP stations is carried out via the AP. However, if a direct link is set up, direct communication is also possible between non-AP stations. On the other hand, in the present invention, the AP is used as a concept including 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. The base wireless communication terminal is used as a term that includes, in a broad sense, the 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.

[0035] 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).

[0036] 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, parts that are the same as or corresponding to the embodiment of FIG. 1 are not redundantly described.

[0037] Since the BSS3 shown in FIG. 2 is an independent BSS that 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.

[0038] 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 an 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.

[0039] 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 may include at least one communication module using different frequency bands. For example, the communication unit 120 may 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.

[0040] 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 user input using various input means, and the processor 110 controls the station 100 based on the received user input. Also, the user interface unit 140 performs output based on the instructions of the processor 110 using various output means.

[0041] 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 instructions of the processor 110. Also, the memory 160 stores control programs used in the station 100 and various data thereby. Such control programs include connection programs necessary for the station 100 to connect to an AP or an external station.

[0042] The processor 110 of the present invention performs various instructions or programs and processes the data inside the station 100. Further, 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 performs a program for connection with the AP stored in the memory 160 and receives a communication setting message transmitted by the AP. Further, the processor 110 reads information regarding the priority condition of the station 100 included in the communication setting message and requests a connection regarding the AP based on the information regarding the priority condition 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 a part of the configuration 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 that modulates and demodulates the radio signal 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.

[0043] 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 are 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. Further, 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.

[0044] FIG. 4 is a block diagram showing the configuration of the AP200 according to an embodiment of the present invention. As shown, the 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 the parts of the configuration of the AP200 that are the same as or correspond to the configuration of the station 100 in FIG. 3.

[0045] Referring to FIG. 4, the AP200 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 AP200 may also include a plurality of communication modules using different frequency bands. That is, the AP200 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, the AP200 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 the AP200. 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.

[0046] Next, the memory 260 stores the control program used in the AP200 and various data thereby. Such control programs include connection programs for managing the connection of 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 a station 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 a 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 radio signal transmission and reception of the AP200 according to an embodiment of the present invention. Detailed embodiments thereof will be described later.

[0047] FIG. 5 is a diagram schematically showing a process in which a STA sets a link with an AP.

[0048] Referring to FIG. 5, the link between the STA100 and the AP200 is set through three major steps of 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 at S103, receives a probe response from the AP at S105, and obtains connection information.

[0049] The STA100 that has successfully received the wireless connection information in the scanning step sends an authentication request (S107a), receives an authentication response from the AP200 (S107b), and performs the authentication step. After the authentication step is performed, the STA100 sends an association request (S109a), receives an association response from the AP200 (S109b), and performs the association step. In this specification, "association" basically means a wireless connection, but the present invention is not limited thereto, and the association in a broad sense includes all wireless connections and wired connections.

[0050] 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 between the STA100 and may be physically connected to the AP200 or exist as a separate server.

[0051] FIG. 6 is a diagram showing the CSMA (Carrier Sense Multiple Access) / CA (Collision Avoidance) method used in wireless LAN communication.

[0052] A terminal performing wireless LAN communication checks whether the channel is busy by performing carrier sensing before transmitting data. If a wireless signal with a certain intensity or higher is detected, the channel is determined to be in a busy state, and the terminal delays access to the channel. Such a process is called Clear Channel Assessment (CCA), and the level for determining the presence or absence of signal detection is called the CCA threshold. If a wireless signal equal to or higher than the CCA threshold received by the terminal has the terminal as the recipient, the terminal processes the received wireless signal. On the other hand, if no wireless signal is detected from the channel or a wireless signal with an intensity smaller than the CCA threshold is detected, the channel is determined to be in an idle state.

[0053] If the channel is determined to be in an idle state, each terminal with data to transmit performs a backoff procedure after a time of IFS (Inter Frame Space) according to the situation of each terminal, such as 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 reducing the slot time by the random number determined for the 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 channel. Thus, the section where each terminal performs the backoff procedure is called the contention window section. At this time, the random number can be called the backoff counter. That is, the initial value of the backoff counter is set by the integer that is the random number obtained by the terminal. When the terminal senses that the channel is idle during the slot time, the terminal can decrement the backoff counter by 1. Also, when the backoff counter reaches 0, the terminal may be permitted to perform channel access on the channel. Therefore, the transmission of the terminal may be permitted when the channel is idle during the AIFS time and the slot time of the backoff counter.

[0054] If a specific terminal successfully accesses the channel, the terminal transmits data via the channel. However, if the terminals attempting access collide with other terminals, 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 terminal. On the other hand, each terminal performs a further backoff procedure in the next contention window period to attempt access, and 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.

[0055] <Examples of various PPDU formats> FIG. 7 shows an example of various standard-generation PPDU (PLCP Protocol Data Unit) formats. More specifically, FIG. 7(a) shows an example of a legacy PPDU format based on 802.11a / g, FIG. 7(b) shows an example of a HE PPDU format based on 802.11ax, and FIG. 7(c) shows an example of a non-legacy PPDU (i.e., EHT PPDU) format based on 802.11be. Also, FIG. 7(d) shows the detailed field configurations of L-SIG and RL-SIG commonly used in the PPDU formats.

[0056] 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 a legacy preamble.

[0057] Referring to FIG. 7(b), the preamble of the HE PPDU further includes RL-SIG (Repeated Legacy Short Training field), HE-SIG-A (High Efficiency Signal A field), HE-SIG-B (High Efficiency Signal B field), HE-STF (High Efficiency Short Training field), and HE-LTF (High Efficiency Long Training field) in addition to the legacy preamble. In 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 modified according to the HE PPDU format. For example, HE-SIG-B may be used only in the HE MU PPDU format.

[0058] Referring to FIG. 7(c), the preamble of the EHT PPDU further includes RL-SIG (Repeated Legacy Short Training field), U-SIG (Universal Signal field), EHT-SIG-A (Extremely High Throughput Signal A field), EHT-SIG-A (Extremely High Throughput Signal B field), EHT-STF (Extremely High Throughput Short Training field), and EHT-LTF (Extremely High Throughput Long Training field) in addition to the legacy preamble. In 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 modified according to the EHT PPDU format. For example, EHT-SIG-A and EHT-SIG-B may be used only in some formats of the EHT PPDU format.

[0059] The L-SIG field included in the preamble of the PPDU is applied with 64 FFT OFDM and consists of a total of 64 subcarriers. Among these, 48 subcarriers excluding the guard subcarriers, DC subcarriers, and pilot subcarriers are used for transmitting the data of L-SIG. Since BPSK and MCS (Modulation and Coding Scheme) with Rate = 1 / 2 are applied to L-SIG, it may contain a total of 24 bits of information. Fig. 7(d) shows the 24-bit information configuration of L-SIG.

[0060] Referring to Fig. 7(d), 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.

[0061] The unit of the L_LENGTH field is byte, and a total of 12 bits are allocated, enabling signaling up to a maximum of 4095. In combination with the L_RATE field, it can indicate the length of the PPDU. At this time, legacy terminals and non-legacy terminals can analyze the L_LENGTH field in different ways.

[0062] First, the method by which a legacy terminal or a non-legacy terminal analyzes the length of the PPDU using the L_LENGTH field is as follows. When the L_RATE field is set to 6 Mbps, 3 bytes (i.e., 24 bits) may be transmitted in a symbol duration of 4 us for 64 FFT. Therefore, adding 3 bytes corresponding to the SVC field and the Tail field to the L_LENGTH field value and dividing this by 3 bytes, which is the transmission amount per 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 the symbol duration, and adding 20 us required for the transmission of L-STF, L-LTF, and L-SIG, the length of the PPDU, i.e., the reception time (RXTIME), is obtained. Expressing this as a mathematical formula is as shown in Equation 1 below.

[0063] [Number]

[0064] At this time, [Number] represents the smallest natural number greater than or equal to x. Since the maximum value of the L_LENGTH field is 4095, the length of the PPDU may be set up to a maximum of 5.484 ms. The non-legacy terminal that transmits the PPDU must set the L_LENGTH field as shown in Equation 2 below.

[0065] [Number]

[0066] Here, TXTIME is the total transmission time for 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 formula, 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 Figure 7(e), the U-SIG (Universal SIG) field persists in EHT PPDUs and PPDUs of subsequent generations of wireless LANs 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 9-bit CRC / Tail are roughly divided into a VI (Version Independent) field and a VD (Version Dependent) field.

[0070] The VI bits continue to maintain the current bit configuration in the future, 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 fields. The PHY version field is 3 bits and serves to sequentially distinguish the 11be and subsequent generations of wireless LAN standards by version. 11be has a value of 000b. The UL / DL field distinguishes whether the PPDU is an uplink / downlink PPDU. BSS color means the BSS identifier defined in 11ax and has a value of 6 bits or more. TXOP means the transmit opportunity duration 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 that is only useful for the 11be version of the PPDU, such as PPDU format and BW, fields that are commonly used in any PPDU format, and fields that are defined differently for each PPDU format. The PPDU format is a discriminator that distinguishes between 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 (the BW that can be expressed in the form of 20 times a power of 2 can be called the basic BW), and various remaining PPDU BWs formed by preamble puncturing. Also, after being signaled at 320 MHz, some 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 a field that appears after the BW field (for example, a field 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 SU PPDU may be signaled in the same PPDU format. A field for distinguishing between the MU PPDU and SU PPDU may be located before the EHT-SIG field, and additional signaling may be performed therefor. Both the SU PPDU and 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, it may have different configurations such as the common fields of the EHT-SIG being omitted or replaced, the user-specific fields being replaced, or 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 the SU PPDU is compressed, the information contained in the compressed field may be signaled together with the uncompressed fields (e.g., common fields, etc.). In the case of the MU PPDU, since it is a PPDU format for simultaneous reception by multiple users, the EHT-SIG field must be transmitted 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 may include the size and position information of the RU assigned to each user.

[0075] In the case of the SU PPDU, a plurality of RUs may be assigned to the STA, and the plurality of RUs may be consecutive or non-consecutive. When the RUs assigned to the 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 the information of the punctured RUs among the RUs assigned to the STA (e.g., the RU puncturing pattern, etc.). That is, in the case of the SU PPDU, a puncturing mode field including information indicating whether the puncturing mode is applied and the puncturing pattern in a bitmap format, etc. may be included in the EHT-SIG field, and the puncturing mode field can signal the 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 EHT-SIG field included in the PPDU. In this case, the terminal can receive the PPDU in the remaining 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 represent the availability of each of the remaining 15 20 MHz subchannels other than the primary channel, and signal the discontinuous channel form (when the form in which only the end 20 MHz is punctured is also regarded as discontinuous). 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 an SU PPDU, and illustrates the discontinuous channel form determined by the proposed method. In addition, a method for signaling the puncturing forms of the primary 160 MHz and 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 in which, in the PPDU format field, the configuration of the PPDU indicated by the preamble puncturing BW value is varied according to the signalized PPDU format. Assuming that the BW field is 4 bits, in the case of an EHT SU PPDU or a TB PPDU, since it is not necessary to further signal one symbol of EHT-SIG-A after U-SIG or to signal EHT-SIG-A from the beginning, considering this, it is necessary to completely signal 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 signalized after U-SIG, up to 11 puncturing modes can be signaled in a different way from the SU PPDU. In the case of an EHT ER PPDU, the BW field is set to 1 bit, and it is possible to signal whether the PPDU uses a 20 MHz or 10 MHz band. The detailed puncturing patterns for each PPDU type will be described in detail later with reference to FIGS. 11 and 12.

[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 an 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. For this purpose, 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 instructing 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 an EHT SU PPDU format for a single STA. The EHT SU PPDU is a PPDU used for single user (SU) transmission between an AP and a single STA, and an EHT-SIG-A field for additional signaling may be located after the U-SIG field.

[0084] FIG. 8(b) shows an example of an EHT trigger-based PPDU format which is an EHT PPDU transmitted based on a trigger frame. The EHT trigger-based PPDU is an EHT PPDU transmitted based on a trigger frame and is an uplink PPDU used for a response 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 an EHT MU PPDU format which is an EHT PPDU for multiple users. The EHT MU PPDU is a PPDU used for transmitting 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 to STAs in an extended range. The EHT ER SU PPDU may be used for single-user transmission to a wider range of STAs than the EHT SU PPDU described in FIG. 8(a), and the U-SIG field may be repeatedly positioned on the time axis.

[0087] The EHT MU PPDU described in FIG. 8(c) can be used by the AP for downlink transmission to multiple STAs. At this time, the EHT MU PPDU may 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 receiver and / or transmitter of the PPDU transmitted through the user specific field of EHT-SIG-B to the STA. 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 may include information regarding the configuration of resource units (e.g., the division form of resource units) in a specific bandwidth (e.g., 20 MHz, etc.) on the frequency axis. 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 specified) to each divided resource unit may be included in the user specific field of EHT-SIG-B and transmitted to the STA. That is, the user specific field may 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 may include the AID of the recipient or the sender, and a user field corresponding to the remaining resource units not used for data transmission may include a pre-set Null STA ID.

[0090] For the sake of convenience in description, in this specification, a frame or a MAC frame may be used in the same meaning as an MPDU.

[0091] When a wireless communication device communicates using a plurality of links, the communication efficiency of the wireless communication device can be improved. At this time, a link is a physical path and may be configured as one wireless medium available for transmitting an MSDU (MAC service data unit). For example, when the frequency band of any one link is in use by another wireless communication device, the wireless communication device can continue to communicate using another link. In this way, the wireless communication device can effectively use a plurality of channels. Also, when the wireless communication device communicates simultaneously using a plurality of links, the overall throughput can be increased. However, existing wireless LANs are defined on the premise that one wireless communication device uses one link. Therefore, a wireless LAN operation method for using a plurality of links is required. With reference to FIGS. 9 to 26, a wireless communication method of a wireless communication device using a plurality of links will be described. First, with reference to FIG. 9, a specific form of a wireless communication device using a plurality of links will be described.

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

[0093] A multi-link device (MLD) may be defined for the wireless communication method using the plurality of links described above. The multi-link device may represent a device having one or more affiliated stations. According to a specific embodiment, the multi-link device may represent a device having two or more affiliated stations. Also, the multi-link device may exchange multi-link elements. The multi-link element may include information regarding one or more stations or one or more links. The multi-link element may include a multi-link setup element to be described later. At this time, the multi-link device may be a logical entity. Specifically, the multi-link device may have a plurality of affiliated stations. The multi-link device may be referred to as an MLLE (multi-link logical entity) or an MLE (multi-link entity). The multi-link device may have one MAC service access point (medium access control service access point, SAP) up to the logical link control (LLC). Also, the MLD may have one MAC data service.

[0094] The plurality of stations included in the multi-link device can operate on a plurality of links. Also, the plurality of stations included in the multi-link device can operate on a plurality of channels. Specifically, the plurality of stations included in the multi-link device can operate on different plural links or different plural channels. For example, the plurality of stations included in the multi-link device can operate on different plural channels of 2.4 GHz, 5 GHz, and 6 GHz.

[0095] The operation of the multi-link device can be referred to as multi-link operation, MLD operation, or multi-band operation. Also, when the station associated with the multi-link device is an AP, the multi-link device can be called an AP MLD. Also, when the station associated with the multi-link device is a non-AP station, the multi-link device can be called a non-AP MLD.

[0096] FIG. 9 shows the operation in which the non-AP MLD and the AP-MLD communicate. Specifically, the non-AP MLD and the AP-MLD communicate using three links each. The AP MLD includes a first AP (AP1), a second AP (AP2), and a third AP (AP3). The non-AP MLD includes a first non-AP STA (non-AP STA1), a second non-AP STA (non-AP STA2), and a third non-AP STA (non-AP STA3). The first AP (AP1) and the first non-AP STA (non-AP STA1) communicate through a first link (Link1). Also, the second AP (AP2) and the second non-AP STA (non-AP STA2) communicate through a second link (Link2). Also, the third AP (AP3) and the third non-AP STA (non-AP STA3) communicate through a third link (Link3).

[0097] Multi-link operation may include a multi-link setup operation. The multi-link setup corresponds to the association operation of the single-link operation described above and needs to precede frame exchange in the multi-link. The multi-link device can obtain the information necessary for the multi-link setup from the multi-link setup element. Specifically, the multi-link setup element may include capability information related to the multi-link. At this time, the capability information may include information indicating whether any one of the plurality of devices included in the multi-link device can transmit while another device can receive. Also, the capability information may include information regarding the links available to each station included in the MLD. Also, the capability information may include information regarding the channels available to each station included in the MLD.

[0098] The multi-link setup may be set by negotiation between peer stations. Specifically, the multi-link setup may be performed by communication between stations without communication with the AP. Also, the multi-link setup may be set through any one of the links. For example, even when the first to third links are set through the multi-link, the multi-link setup may be performed through the first link.

[0099] In addition, a mapping between a TID (traffic identifier) and a link may be set. Specifically, frames corresponding to a specific value of the TID may be exchanged only through a pre-specified link. The mapping between the TID and the link may be set in a directional-based manner. For example, when a plurality of links are set between a first multi-link device and a second multi-link device, the first multi-link device may be set to transmit frames of a first TID to a plurality of first links, and the second multi-link device may be set to transmit frames of a second TID to the first link. Also, a basic setting may exist for the mapping between the TID and the link. Specifically, when there is no additional setting in the multi-link setting, the multi-link device can exchange frames corresponding to the TID on each link according to the basic (default) setting. At this time, the basic setting may be such that all TIDs are exchanged on any one of the links.

[0100] Specifically describe the TID. The TID is an ID for classifying traffic and data to support QoS (Quality of Service). Also, the TID may be used or assigned in a layer higher than the MAC layer. Also, the TID can indicate a traffic category (TC) or a traffic stream (TS). Also, the TID may be distinguished into 16. For example, the TID may be specified as any one of 0 to 15. It may be specified that the TID values used are different depending on the access policy, channel access, or medium access method. For example, when EDCA (Enhanced Distributed Channel Access) or HCAF (Hybrid Coordination Function Contention Based Channel Access) is used, the value of the TID may be assigned in the range of 0 to 7. When EDCA is used, the TID can indicate the user priority (UP). At this time, the UP may be specified by the TC or TS. The UP may be assigned in a layer higher than the MAC. Also, when HCCA (HCF Controlled Channel Access) or SPCA is used, the value of the TID may be assigned in the range of 8 to 15. When HCCA or SPCA is used, the TID can indicate the TSID. Also, when HEMM or SEMM is used, the value of the TID may be assigned in the range of 8 to 15. When HEMM or SEMM is used, the TID can indicate the TSID.

[0101] UP and AC (access category) may be mapped. AC may be a label for providing QoS in EDCA. AC may be a label for indicating an EDCA parameter set. The EDCA parameter or EDCA parameter set is a parameter used in the channel contention of EDCA. The QoS station can guarantee QoS using AC. Also, AC may include AC_BK, AC_BE, AC_VI, and AC_VO. Each of AC_BK, AC_BE, AC_VI, and AC_VO can indicate background, best effort, video, and voice. Also, AC_BK, AC_BE, AC_VI, and AC_VO may be classified into lower-level ACs. For example, AC_VI can be subdivided into AC_VI primary and AC_VI alternate. Also, AC_VO can be subdivided into AC_VO primary and AC_VO alternate. Also, UP or TID may be mapped to AC. For example, each of 1, 2, 0, 3, 4, 5, 6, 7 in UP or TID may be mapped to each of AC_BK, AC_BK, AC_BE, AC_BE, AC_VI, AC_VI, AC_VO, AC_VO. Also, each of 1, 2, 0, 3, 4, 5, 6, and 7 in UP or TID may be mapped to each of AC_BK, AC_BK, AC_BE, AC_BE, AC_VI alternate, AC_VI primary, AC_VO primary, AC_VO alternate. Also, 1, 2, 0, 3, 4, 5, 6, and 7 in UP or TID may be in descending order of priority. That is, 1 may have a lower priority and 7 may have a higher priority. Therefore, the priority may increase in the order of AC_BK, AC_BE, AC_VI, AC_VO. Also, each of AC_BK, AC_BE, AC_VI, and AC_VO may correspond to each of ACI (AC index) 0, 1, 2, 3. Due to the characteristics of such TIDs, the mapping between TID and link can represent the mapping between AC and link.Also, the mapping between the link and the AC can represent the mapping between the TID and the link.

[0102] As described above, a TID may be mapped to each of a plurality of links. The mapping may be such that a link through which traffic corresponding to a specific TID or AC can be exchanged is specified. Also, a TID or AC that can be transmitted in the link may be specified for each transmission direction within the link. As described above, there may be a basic setting for the mapping between the TID and the link. Specifically, when there is no additional setting in the multi-link setting, the multi-link device can exchange frames corresponding to the TID on each link according to the basic (default) setting. At this time, the basic setting may be such that all TIDs are exchanged on any one link. At all times, at a certain point in time, any TID or AC may be mapped to at least one link. Management frames and control frames may be transmitted on all links.

[0103] When a link is mapped to a TID or AC, only the data frame corresponding to the TID or AC mapped to the link may be transmitted on the link. Therefore, when a link is mapped to a TID or AC, frames that do not correspond to the TID or AC not mapped to the link do not have to be transmitted on the link. When a link is mapped to a TID or AC, the ACK may also be transmitted based on the link to which the TID or AC is mapped. For example, a block ACK agreement may be determined based on the mapping between the TID and the link. In still other specific embodiments, the mapping between the TID and the link may be determined based on the block ACK agreement. Specifically, a block ACK agreement may be set for the TID mapped to a specific link.

[0104] By the mapping between the above-mentioned TID and the link, QoS may be guaranteed. Specifically, a relatively small number of stations may operate, or a high-priority AC or TID may be mapped to a link with a good channel state. Also, by the mapping between the above-mentioned TID and the link, a station can be made to maintain a power-saving state for a longer time.

[0105] FIG. 10 shows a multi-link mapped by a TID-to-link mapping method according to an embodiment of the present invention.

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

[0107] Also, the TID may be an ID used or assigned in a layer higher than the MAC layer. The TID can indicate TC (traffic categories) and TS (traffic streams). Also, the TID may be 16 values, for example, indicated as values from 0 to 15. Also, depending on the access policy, channel connection, or medium access method, the TID values used may be different. For example, when using EDCA (HCF (hybrid coordination function) contention based channel connection, enhanced distributed channel connection), the possible TID values may be from 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 in a layer higher than the MAC layer. Also, when using HCCA (HCF controlled channel access) or SPCA, the possible TID values may be from 8 to 15. Also, when using HCCA or SPCA, the TID may indicate the TSID. Also, when using HEMM or SEMM, the possible TID values may be from 8 to 15. Also, when using HEMM or SEMM, the TID may indicate the TSID.

[0108] Also, 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 connection. The AC may be used by a QoS STA.

[0109] The value of AC may be set as one of AC_BK, AC_BE, AC_VI, and AC_VO. AC_BK, AC_BE, AC_VI, and AC_VO may represent background, best effort, video, and voice, respectively. Also, 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 mapped to AC_BK, AC_BK, AC_BE, AC_BE, AC_VI, AC_VI, AC_VO, AC_VO, respectively. Or, the UP value or the TID values 1, 2, 0, 3, 4, 5, 6, 7 may be mapped to AC_BK, AC_BK, AC_BE, AC_BE, AC_VI alternate, AC_VI primary, AC_VO primary, AC_VO alternate, respectively. Also, the UP value or the TID values 1, 2, 0, 3, 4, 5, 6, 7 may be in the order of decreasing priority. That is, 1 may have a lower priority and 7 may have a higher priority. Therefore, the priority may increase in the order of AC_BK, AC_BE, AC_VI, and AC_VO. Also, AC_BK, AC_BE, AC_VI, and AC_VO may correspond to AC indexes (ACI) 0, 1, 2, 3, respectively.

[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. Also, in the present invention, the fact that TID is mapped may mean that AC is mapped, or vice versa.

[0111] According to an embodiment of the present invention, there may be TIDs mapped to each link of a multi-link. For example, there may be a mapping for which link among a plurality of links is allowed to transmit and receive a specific TID or a specific AC. Also, such a mapping may be defined separately for each of both directions of the link. Also, as described above, there may be a basic (default) setting for the mapping between the TID and the link. For example, the mapping between the TID and the link may basically be such that all TIDs are mapped to a certain link. Also, according to an embodiment, at a specific point in time, 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 a certain direction of a link may be transmitted. Also, a data frame corresponding to a TID or an AC not mapped to a certain 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 the block ack agreement. For example, it is possible that there is a block ack agreement for a TID mapped by the TID-to-link.

[0114] By performing TID-to-link mapping, it is possible to provide QoS services. For example, by mapping a high-priority AC and TID to a link with a good channel condition or few STAs, it may be possible to transmit the data of the AC and TID quickly. Or, by performing TID-to-link mapping, it can help the STAs of a specific link to be able to save power (or enter the doze state).

[0115] Referring to FIG. 10, an AP MLD including AP1 and AP2 may exist. Also, a Non-AP MLD including STA1 and STA2 may exist. 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 via Link1 and the link for transmitting from STA1 to AP1 via Link1. Also, only AC_VO or the TIDs corresponding to AC_VO may be mapped to the link for transmitting from STA2 to AP2 via Link2. Also, only the data of the mapped TID and / or AC can be transmitted over the link. Also, the data of the TID or AC not mapped to the link cannot be transmitted over 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 (STR; simultaneous transmit and receive; simultaneous transmission and reception) in which the MLD simultaneously transmits or receives may be restricted, and this 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, simultaneously transmitting or receiving may be restricted, and when the interval between links is n MHz for n greater than m, simultaneously transmitting or receiving may not be restricted. This embodiment may be for solving the problem that simultaneously transmitting or receiving is restricted, and duplicate explanations can be omitted. Further, this embodiment can be applied to the MLD that does not support STR.

[0121] According to an embodiment of the present invention, duration information may be shared among links operating in multiple links. 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 the Duration / ID field included in the MAC header. As yet another example, the duration information may be the duration information indicated by the Length field (L Length field) included in the 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 the TXOP duration. According to an embodiment, the duration information indicated by the L-SIG field may be the length of the 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 limit transmission or channel connection during a period based on the duration information shared among links. The method of limiting transmission or channel connection may include setting the 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, an STA belonging to the MLD can set the 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 on multiple links. For example, transmission on link 2 may not be necessary based on the inter-link NAV set based on the period information received on link 1. Also, the inter-link NAV can exist or be used for an STR-infeasible MLD. For example, when the inter-link NAV is set, the MLD that set the inter-link NAV does not have to transmit or connect to a channel on a plurality of links (or all links used by the MLD).

[0124] In addition to the intra-BSS NAV, a basic NAV may also 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, there may be situations where it is acceptable to reset the NAV set by other links. For example, an inter-link NAV may be set based on a certain frame (or PPDU), but if it is determined that the frame (or PPDU) is not directed to the same MLD, the set inter-link NAV may be reset. 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 of Link 1 can be updated based on the frame of Link 2. And if the NAV of Link 1 is reset when there is no longer a need to maintain the NAV by Link 2, the NAV information set based on the frame received on Link 1 may be lost. If the inter-link NAV is used together with the NAV for each link, such problems can be solved because the NAV for each link can be maintained even if the inter-link NAV is reset.

[0126] In the embodiments of the present invention, setting the NAV is taken as an example, but the embodiments of the present invention are not limited thereto, and it can also be applied to instructing to interrupt the channel connection in the physical layer or instructing the channel state to be busy. Also, it is not limited to resetting the NAV, and it may also be applied to instructing to continue the channel connection in the physical layer or instructing the channel state to be idle. At this time, the primitives exchanged between the physical layer and the MAC layer may be used. Or, the primitives exchanged between one STA of the MLD and other STAs may be used. Or, the 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 need to stop channel connection. As described above, the channel connection can be stopped based on the received period information. However, due to the time required for the position or decoding of the field including the period information, there may be a time from when the PPDU starts to be received until the period information is obtained. Therefore, if transmission starts by accessing the channel during this time, the above-described problem may occur. Therefore, 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 resumed.

[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 description regarding the specific method of the embodiment described in FIG. 11, and overlapping 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. Also, 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. Hereinafter, these operations can be instructed as suspending and resuming channel connection. Also, hereinafter, it can be described that STA1 and STA2 belong to the MLD, and STA1 and STA2 operate on link 1 and link 2, respectively. Also, the frame and PPDU can be used interchangeably for instruction. Also, 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 can interrupt the channel connection. Also, when STA1 obtains the duration information from the L-SIG, STA2 can maintain the state of interrupting the channel connection. At this time, STA2 can determine that the state of interrupting the channel connection continues until the end of the frame received by STA1. Also, when STA1 cannot correctly decode the L-SIG (in the case of an invalid L-SIG), STA2 can resume the channel connection.

[0132] Also, STA1 may 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, at this time, the period for interrupting the channel connection may be until the end of the received frame. In this case, there is an advantage that the channel connection can be started earlier after the received frame ends. As another example, at this time, the period for interrupting the channel connection may be the TXOP duration. In this case, the period of the channel connection interrupted based on the L-SIG can 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 indicate that it is not intra-BSS or the BSS color does not correspond to the BSS color of STA1. Alternatively, STA1 may not be able to successfully decode the U-SIG. In such a case, STA2 can resume the channel connection.

[0134] Alternatively, when the information obtained from the U-SIG of the frame received by STA1 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 ID that cannot be recognized, STA2 can resume the channel connection.

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

[0136] Also, 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, or the STA-ID indicates the group to which STA1 belongs, or the STA-ID indicates broadcast, STA2 can maintain the state of interrupting the channel connection.

[0137] Or, 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, or the STA-ID does not indicate the group to which STA1 belongs, or the STA-ID 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] Also, although the case of receiving an EHT-SIG has been described, the same embodiment can also be applied to the case of receiving an HE-SIG-B when receiving an HE PPDU. For example, the HE-SIG-B may include a STA-ID, and thus, the same operations as described above can be performed.

[0139] Also, 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 a value that STA1 should receive, for example, when the RA or DA indicates STA1, or the group to which STA1 belongs, or the STA-ID indicates broadcast, STA2 can maintain the state of interrupting the channel connection. At this time, the period of interrupting the channel access can be obtained based on the period information included in the received MAC header. More specifically, the period of interrupting the 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 it does not indicate an indicator corresponding to STA1, does not indicate a group to which STA1 belongs, and does not indicate broadcast, STA2 can resume the channel connection. Or, STA1 may not be able to receive 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 interruption and resumption of the channel connection described in FIG. 12 can operate sequentially in the order of decoding by starting to receive a frame (or PPDU) at STA1 and decoding it in that order. The decoding order can 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 a PPDU or RU (resource unit). Also, the STA-ID may be included in an 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 the received frame or the received PPDU corresponds to the BSS to which the STA that classifies belongs. Or, classifying a BSS can mean an operation of classifying whether the received frame or the received PPDU is transmitted from the BSS to which the STA that classifies belongs. Further, classifying a BSS may include an operation of classifying whether the received frame or the received PPDU corresponds to a BSS to which the STA that classifies does not belong. Or, classifying a BSS can mean an operation of classifying whether the received frame or the received PPDU is transmitted from a BSS to which the STA that classifies does not belong. Also, classifying a BSS may include an operation of classifying to which BSS the received frame or the received PPDU belongs. Or, classifying a BSS can mean an operation of classifying from which BSS the received frame or the received PPDU is transmitted. According to an embodiment of the present invention, the BSS to which the STA that classifies belongs can be called an intra-BSS. Or, the BSS including the BSS to which the STA that classifies 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 that classifies 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 respectively referred to as an intra-BSS frame and an intra-BSS PPDU. 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 respectively referred to as an inter-BSS frame and an inter-BSS PPDU. 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, the BSS can be classified according to whether 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 RXVECTOR can be called TXVECTOR parameter and RXVECTOR parameter, respectively. Also, the BSS color may be included in the TXVECTOR parameter or the RXVECTOR parameter. 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. Further, the MAC address may include an RA (receiver address), a TA (transmitter address), a BSSID, an SA (source address), a DA (destination address), and the like. 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 to which the STA belongs, the received frame can be classified as an inter-BSS frame. More specifically, if all of the MAC addresses included in the received frame are different from the BSSID of the BSS to which the STA belongs, 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 to which the STA belongs, 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 to which the STA belongs, the received frame can be classified as an intra-BSS frame.

[0149] The corresponding BSS may include the BSS to which the STA is associated. Further, the corresponding BSS may include the BSS included in the same multi-BSSID set as the BSS to which the STA is associated. Also, the corresponding BSS may include the BSS included in the same co-hosted BSSID set as the BSS to which the STA is associated. Also, information regarding the one or more BSSs included in the same multi-BSSID set or the same co-hosted BSSID set may be transmitted by 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 the 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 set 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 the 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 still other embodiments, 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 preset 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 the 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 the 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 can be included in the TXVECTOR parameter PARTIAL_AID or the RXVECTOR parameter PARTIAL_AID. Also, the Group ID field value can be included in the TXVECTOR parameter GROUP_ID or the RXVECTOR parameter GROUP_ID.

[0152] The BSS classification condition may include a condition for the AP to receive a PPDU with a pre-set condition. For example, the PPDU with the pre-set condition 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 signaling indicating whether it is an uplink or a downlink is set to a pre-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 as an intra-BSS PPDU or an inter-BSS PPDU. For example, when neither the condition for classifying as the intra-BSS PPDU nor the condition for classifying as the inter-BSS PPDU described above is satisfied, it may not be classified as an intra-BSS PPDU or an inter-BSS PPDU.

[0154] Also, when classifying the BSS, when the classification results based on multiple conditions do not match, it is possible to determine the final result according to the pre-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 take precedence, or the result based on the condition based on the MAC address may be determined as the final result. Or, when both the condition for classifying as an intra-BSS PPDU and the condition for classifying as an inter-BSS PPDU are satisfied, it can be classified as an 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. When the already set conditions are satisfied, it is possible to perform the intra-PPDU power save operation. 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 such that the STA that received the PPDU does not support it, 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 such that the STA that received the PPDU does not support it, a 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 to be used when responding, the PHY configuration to be used when responding, the MAC configuration, etc. The intra-PPDU power save 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] The operation based on the classified BSS may include an operation of setting (or updating) the NAV. According to one embodiment, the STA can operate one or more NAVs. Also, when the 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 BSSs may include spatial reuse operations. Also, operations based on the classified BSSs may include channel connection operations. The spatial reuse operation may be a channel connection operation. When a STA receives a PPDU or a frame, it is possible to perform a spatial reuse operation if the already set conditions are met. 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 less than a threshold value. For example, the threshold value may be variable. Also, the threshold value may be a threshold value for OBSS PD-based spatial reuse operations. Also, the threshold value may be a value equal to or greater than the CCA threshold value. Also, the threshold value may be a value based on the power to be transmitted. The spatial reuse operation may include an operation of transmitting a PPDU. Also, the spatial reuse operation may include an operation of resetting the PHY. For example, the operation of resetting the PHY may be an operation of issuing a PHY-CCARESET.request primitive. Also, the spatial reuse operation may include an operation of not setting the NAV based on the received PPDU or the received frame. If the STA performs a spatial reuse operation, it may be 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 each other in inter-BSS. That is, a PPDU or frame transmitted by a STA associated with BSS B at BSS A may be classified as an inter-BSS PPDU or an inter-BSS frame. Also, there may be STA1 and STA2 belonging to (or associated with an AP operating BSS A). There may be 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 aforementioned BSS. 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 a UL PPDU or a PPDU for which the STA is not the intended recipient. Therefore, according to the above-described embodiments, STA2 can perform intra-PPDU power saving. Referring to FIG. 13, STA2 may enter the doze state until the end time 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. Further, 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. Further, the signal strength of the PPDU received by STA4 may be smaller 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 smaller 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 may be 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 an 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 supporting 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. Also, an HT STA can support not only the functions of an OFDM PHY STA but also additional functions not supported by the OFDM PHY STA. A VHT STA can support functions not supported by an HT STA while supporting the basic functions of the HT STA. A VHT STA may be classified as an HT STA. Also, an HE STA can support functions not supported by a VHT STA while supporting the basic functions of the VHT STA. An HE STA may be classified as a VHT STA. Also, an EHT STA can be an HE STA. Also, an EHT STA can support functions not supported by an HE STA while supporting the basic functions of the HE STA. 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 functions not supported by an EHT STA while supporting the basic functions of the EHT STA. A NEXT STA may be classified as an EHT STA.

[0164] FIG. 14 is a diagram showing the relationship between STAs supporting each wireless LAN standard. Referring to FIG. 11, 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. 16 shows the UL 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 transmit an immediate response simultaneously. In this specification, an immediate response indicates that the interval between the previously received PPDU and the PPDU including the response is SIFS. Specifically, it may be to transmit a response after SIFS from the end of the received PPDU.

[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 to a triggering frame. The TB PPDU may include an 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 contains L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG-A, HE-STF, HE-LTF in that order, 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 contains L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, (EHT- / NEXT-)STF, (EHT- / NEXT-)LTF in that order, 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 (B3 B2) of the MAC frame is 01b and the value of the Subtype subfield (B7 B6 B5 B4) is 0010b, it can indicate that the MAC frame is a trigger frame.

[0170] When multiple STAs responding to a triggering frame transmit TB PPDUs in different formats, the access point may have difficulty receiving the TB PPDUs. Also, when the preambles of the PPDUs transmitted by multiple STAs are different from each other, the access point may have difficulty receiving the TB PPDUs. In particular, when the RUs in which TB PPDUs of different formats are transmitted overlap, the access point may have difficulty receiving the TB PPDUs. Therefore, multiple STAs transmitting responses to one triggering frame can use TB PPDUs in 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, the HE STA can transmit an HE TB PPDU. Also, the EHT STA can transmit an EHT TB PPDU or an HE TB PPDU. Further, the NEXT STA can transmit a NEXT TB PPDU, an EHT TB PPDU, or an HE TB PPDU.

[0172] In the embodiment of FIG. 15, the AP transmits a trigger frame that schedules the transmission 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 to be 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 can transmit TB PPDUs in different formats. For this reason, the transmission of the TB PPDU may fail, wasting the transmission opportunity. 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 is described in FIG. 13.

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

[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 STAs 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 extending the frame length to ensure the time required for the receiving STA 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 subtype. Also, depending on the Trigger Type subfield, the Trigger Dependent Common Info subfield and the length of the information and the Trigger Dependent User Info subfield included in the Trigger Dependent User Info subfield may be determined. For example, the Trigger Type subfield can be indicated by bits B0 to B3 of the Common Info field.

[0176] In addition, 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 can 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 the bits from B4 to B15 of the Common Info field.

[0177] In addition, 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, such as 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] In addition, the Common Info field may include information included in the signaling field of the TB PPDU that responds to the trigger frame, such as the HE-SIG-A field or the U-SIG field.

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

[0180] In addition, 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 in the User Info field including the AID12 subfield may be information corresponding to the STA indicated by the AID12 subfield. Further, 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 of the trigger frame including the User Info field.

[0181] As described above, problems may occur depending on the format of the PPDU in which 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. 14.

[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. Further, 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 with one frame or one PPDU. Thereby, the usage efficiency of the transmission medium can be improved. For example, a HE STA that does not support the EHT standard and an EHT STA can be made to respond with a HE TB PPDU in one frame.

[0184] In addition, 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, trigger frames can be classified into HE trigger frames, EHT trigger frames, and NEXT trigger frames. Also, responses triggered by HE trigger frames, EHT trigger frames, and NEXT trigger frames can be responded to with HE TB PPDUs, EHT TB PPDUs, and NEXT TB PPDUs, respectively.

[0186] Also, classifying HE trigger frames, EHT trigger frames, and NEXT trigger frames may have the same meaning as classifying the TB PPDU formats responding to the trigger frames into HE TB PPDUs, EHT TB PPDUs, and NEXT TB PPDUs, respectively. That is, the format of the TB PPDU corresponding thereto may change depending on 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 HE TB PPDUs and EHT TB PPDUs simultaneously. However, the HE trigger frame cannot instruct the transmission of EHT TB PPDUs.

[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. When the value of the Type subfield of the Frame Control field of the MAC header is 01b and the value of the Subtype subfield is 0010b, the trigger frame may be classified as an HE trigger frame. Each of the Type subfield, the Subtype subfield, and the Control Frame Extension subfield is limited to 2 bits, 4 bits, and 4 bits, respectively. Therefore, such an embodiment has a disadvantage of restricting types that can be used in the future using limited bit field values.

[0188] In yet other specific embodiments, 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 Common Info field included in the trigger frame. 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 an 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 from 0 to 7, the trigger frame may be classified as an HE trigger frame. Also, when the value of the Trigger Type subfield in the Common Info field of the trigger frame is not from 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 using limited bitfield values.

[0189] In yet another specific embodiment, it may be determined which type of trigger frame the trigger frame corresponds to among the HE trigger frame, the EHT trigger frame, and the NEXT trigger frame 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 type of trigger frame the trigger frame corresponds to among the HE trigger frame, the EHT trigger frame, and the NEXT trigger frame 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 type of trigger frame the trigger frame corresponds to among the HE trigger frame, the EHT trigger frame, and the NEXT trigger frame based on the User Info field included in the trigger frame. Specifically, it may be determined which type of trigger frame the trigger frame corresponds to among the HE trigger frame, the EHT trigger frame, and the NEXT trigger frame based on the value of the AID12 subfield in the User Info field of the trigger frame. For example, it may be determined which type of trigger frame the trigger frame corresponds to among the HE trigger frame, the EHT trigger frame, and the NEXT trigger frame based on whether the value of the AID12 subfield in 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 prior to 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 arising from the fact that a legacy STA, i.e., an 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 since the User Info field is for indicating the trigger frame type, information other than the trigger frame type may not be necessary.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 the trigger frame including the AID12 field 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 the trigger frame including the AID12 field triggers the transmission of a NEXT TB PPDU. The second value may be 2048.

[0191] In yet another specific embodiment, 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 the User Info field including the AID12 field having a predetermined 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 the User Info field including the AID12 field having a first value and after the User Info field including the AID12 field having a second value. In the embodiment of FIG. 17, when the User Info field that triggers the STA is located after the User Info field including the AID12 field 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 the User Info field including the AID12 field 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 after the User Info field including the AID12 field having 2047 and the User Info field including the AID12 field 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 the User Info field including the AID12 field having 2047 and the User Info field including the AID12 field having 2048, the STA can transmit a HE TB PPDU as a response to the trigger frame.

[0192] Sub-fields of the User Info field other than the AID12 sub-field may determine which trigger frame among the HE trigger frame, EHT trigger frame, and NEXT trigger frame the trigger frame corresponds to.

[0193] The Padding field of 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, 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, EHT trigger frame, and NEXT trigger frame the trigger frame corresponds to.

[0194] Also, the above-described embodiments may be applied in combination. For example, elements that affect determining whether the above-described trigger frame is an HE trigger frame, an EHT trigger frame, or a NEXT trigger frame can be determined in combination.

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

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

[0197] As described above, the trigger frame may include the TRS in the MAC frame header. The TRS may be included in the HT Control field as described above. Specifically, the HT Control field may include the TRS when it includes the A-Control field. 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] The STA corresponding to the intended recipient of the MAC frame containing the TRS can transmit a PPDU based on the field containing 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 transmitting a response 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 transmitting a response to the MAC frame containing the TRS (UL HE-MCS) may be included.

[0199] The TRS may be defined separately for each wireless LAN standard. At this time, the STA that has received the MAC frame containing the 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 the STA receives a HE TRS, the STA can transmit a HE TB PPDU as a response to the TRS. Also, when the STA receives an EHT TRS, the STA can transmit an EHT TB PPDU as a response to the TRS. Also, when the 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 can be classified into a HE TRS and a non-TRS TRS.

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

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

[0202] Also, depending on the PPDU format that includes the TRS, the information indicated by the subfields 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, for example, 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, for example, 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, for example, the UL HE-MCS subfield, can indicate a value corresponding to the NEXT MCS table. Also, depending on the PPDU format that includes 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 can share the TXOP or receive TXOP sharing.

[0205] Specifically, after the STA transmits a frame for setting the TXOP, it can set (or acquire) the TXOP by receiving a response thereto. After the STA sets the TXOP, it can perform 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 may be obtained 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 within the set TXOP. That is, one or more TXOPs may be shared with other STAs within the TXOP set by the STA.

[0208] A STA that has received TXOP sharing can transmit a PPDU within the shared TXOP to the STA that shared the TXOP or another STA. 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 received TXOP sharing can transmit a PPDU without receiving a trigger frame from the AP within the shared TXOP. In other words, a STA that has received TXOP sharing can use the RU allocated by the trigger frame transmitted when receiving TXOP sharing to transmit a PPDU until the shared TXOP ends without receiving an additional trigger frame even if a separate RU is not individually allocated by the trigger frame within the shared TXOP. Therefore, examples of PPDUs transmitted by a STA within the shared TXOP can include non-HT PPDUs, HE PPDUs, VHT PPDUs, HE SU PPDUs, or EHT MU PPDUs.

[0209] In TXOP sharing, a STA that has received TXOP sharing within the shared 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 received TXOP sharing can transmit a frame to the AP or the 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 may be a P2P (peer to peer) frame.

[0210] Such sharing of a TXOP may be set by a specific frame. That is, it may be indicated that part or all of the TXOP set by the specific frame is to be shared, and the STA can use the shared TXOP upon receiving the frame. 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 an AP. In this case, the trigger frame for TXOP sharing may be a specific type of trigger frame (e.g., MU-RTS frame, or 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 (e.g., "3"), the STA that receives the trigger frame can recognize that the TXOP is shared and can transmit a PPDU using the shared TXOP.

[0211] The MU-RTS frame, which is a frame for sharing a 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 a TXOP may be referred to as a modified MU-RTS frame or an MU-RTS TXS trigger frame. However, it is not limited thereto, and the frame for sharing a TXOP may be used with various names.

[0212] Sharing of part or all of a TXOP may be set only for one STA or for one or more STAs. That is, in sharing a TXOP using a frame, one or more STAs for TXOP sharing may be indicated 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 cannot exceed the TXOP set by the STA that shares it.

[0213] The duration of the shared TXOP may be indicated by a specific frame for sharing the TXOP (e.g., a modified MU-RTS frame). 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, section information for transmitting the TB PPDU) when the trigger frame indicates the transmission of the TB PPDU.

[0214] Whether the transmitted MU-RTS frame is a MU-RTS frame (modified MU-RTS frame) for sharing the TXOP or a MU-RTS frame not used for sharing 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, it may be identified whether the MU-RTS frame is a trigger frame for sharing the TXOP according to 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 the TXOP.

[0215] Alternatively, whether the received frame is a MU-RTS frame for TXOP sharing may be determined based on whether the MU-RTS frame includes a specific field 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, it may be determined whether the received MU-RTS frame is a frame for TXOP sharing based on the number of user information fields included in the MU-RTS frame. 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 TXOP sharing. At this time, when the MU-RTS frame is not a frame for TXOP sharing, 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 by 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 the STA that has received TXOP sharing in the shared TXOP described above and a PPDU including the frame transmitted by the STA that has received TXOP sharing in 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, in the present invention, what is denoted as the MU-RTS frame 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 with the shared TXOP described above. Or, the frame transmitted immediately after transmitting the CTS frame may be transmitted included in the non-TB PPDU described above. Also, in the present invention, transmitting immediately can mean transmitting at a time point after 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 be transmitted in response to a modified MU-RTS frame. Also, a STA that receives TXOP sharing immediately after a modified MU-RTS frame can transmit a frame. Or, a STA that receives TXOP sharing immediately after a PPDU including a modified MU-RTS frame can transmit the PPDU. At this time, the frame to be transmitted may be included in a PPDU transmitted by the STA that received TXOP sharing with the shared TXOP described above. Or, at this time, the frame to be transmitted may be included in and transmitted by the non-TB PPDU described above. Also, in the present invention, transmitting immediately thereafter can mean transmitting at a time delayed by only SIFS or PIFS from the end of the PPDU including the modified MU-RTS frame.

[0220] According to one embodiment, a modified MU-RTS frame may include signaling for whether a STA that receives TXOP sharing should transmit a CTS frame. According to one embodiment, when transmitting a frame that a STA that receives TXOP sharing sends to an AP, it is possible to use a shared TXOP without a CTS frame. Also, when transmitting a P2P frame, a STA that receives TXOP sharing can transmit a CTS frame and use the shared TXOP. Also, when transmitting a P2P frame, a STA that receives TXOP sharing, the RA field of the CTS frame transmitted immediately after the modified MU-RTS frame can be set to the MAC address of the STA that transmitted the modified MU-RTS frame. This is because when a STA that receives 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 that shares the TXOP to know whether the STA that receives the 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 period information regarding TXOP duration. The MU-RTS frame can induce CTS frames 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 a TXOP holder. A TXOP holder may be an STA that has obtained a TXOP. A TXOP holder can transmit a frame that it wants to transmit with the TXOP. Also, in this case, STA2 can become a TXOP responder. A TXOP responder may be an STA that has transmitted a response to a frame sent by a TXOP holder. A TXOP responder can transmit a response to a frame sent by a TXOP holder with the TXOP. Or, a TXOP responder can transmit a frame permitted by a TXOP holder with the TXOP. In the embodiment of FIG. 19, an example in which a TXOP is acquired based on the exchange of MU-RTS frames and CTS frames has been described. However, the present invention is not limited to this and can also be applied to cases where a TXOP is acquired 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 have an AID12 sub-field value that can indicate STA2. That is, the User Info field included in the modified MU-RTS frame can have an AID12 sub-field value that can indicate the 12 LSBs of the AID of STA2. 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, STA2 can transmit a frame after transmitting the CTS frame. The frame transmitted by STA2 after transmitting 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, STA2 can transmit a frame that is not a CTS frame after the modified MU-RTS frame is transmitted. Also, according to one embodiment, the frame that is not a CTS frame transmitted by STA2 after receiving the modified MU-RTS frame can be a frame transmitted to STA1. According to other embodiments, the frame that is not a CTS frame transmitted by STA2 after receiving the modified MU-RTS frame can 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 some 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 parsed as the GI And HE-LTF type subfield. However, 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 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 some 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 sharing mode of the TXOP. For example, the GI And HE-LTF type / triggered TXOP sharing mode subfield indicates whether the sharing of the TXOP 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", with the shared TXOP, the STA can only send PPDUs to the AP.However, when the value of the GI And HE-LTF type / triggered TXOP sharing mode subfield is "2", in the shared TXOP, the STA can transmit PPDUs not only to the AP but also to other STAs. 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 in 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 TXOP sharing 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 of difficulty in performing the operations described in FIG. 19 and a solution thereto. The content described in FIG. 19 can 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, 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 plurality 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 that 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 a different BSS may be made 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 an 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 an embodiment of the present invention, when the CS is busy, the STA may be unable 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 satisfy the already set conditions.

[0234] According to an embodiment, a STA may be able to transmit regardless of the NAV (or without considering the NAV) when the received frame is addressed to the STA and an immediate response is required. 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 may be able to transmit regardless of the NAV when the received frame is addressed to the STA and an immediate response is required. Also, when a frame is addressed to a STA, it may include the case where the RA field of the frame is set to the address of the STA. Or, when a frame is addressed to a 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, the STA may be able to transmit a response to a received frame regardless of the NAV when the received frame is transmitted from a TXOP holder. At this time, the NAV may be the NAV set by the frame or PPDU sent by the TXOP holder. Or, the NAV may be an intra-BSS NAV. Also, the received frame may be an RTS frame. That the frame is transmitted from a TXOP holder can be determined based on the TA field included in the frame. The STA can save the TXOP holder address. If the STA receives an RTS frame sent by the TXOP holder and the RTS frame is addressed to the STA, it 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 still other embodiments, when the STA receives a trigger frame, it may be able to 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 regardless of the NAV when the response is indicated by the trigger frame. When the STA receives a trigger frame, it can determine whether to send a response thereto by 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 for determining 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 indicates that it is determined 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 as the virtual CS and to consider the basic NAV. Also, if the CS Required subfield indicates that a response is to be sent 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 NAV is set for the STA that has received the modified MU-RTS frame, it may be impossible to send a frame other than the CTS frame in the shared TXOP. This will be further described with reference to FIG. 20.

[0238] The content described in FIG. 19 in relation to 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 other frame exchanges occur 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 in STA2, it may be difficult to send frames. For example, the NAV may be set by a frame sent by STA2 to obtain a TXOP before STA1 allocates the shared TXOP. That is, the NAV may be set when STA2 receives a frame sent before STA1 sends a modified MU-RTS frame. Or, STA2 may receive a frame sent from another STA with the same TXOP before receiving the modified MU-RTS frame addressed to itself and the NAV may be set. Or, the NAV may be set based on the modified MU-RTS frame addressed to STA2. 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 frames.

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

[0241] That is, when a STA has received TXOP sharing, it can transmit a PPDU regardless of the NAV set within the shared TXOP. Specifically, when the AP transmits a trigger frame for TXOP sharing, the NAV may be set by the AP within the shared TXOP. In this case, a STA that has received TXOP sharing may become unable to transmit a PPDU due to the NAV set within the shared TXOP. Therefore, a STA that has received TXOP sharing 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 described as a frame can also apply the invention in place of a PPDU including the frame.

[0243] Also, at this time, the frame transmitted by the STA that has received TXOP sharing regardless of the NAV may be transmitted after a SIFS from the previous PPDU.

[0244] According to still other embodiments, when a STA that has received TXOP sharing transmits a frame, it is possible to consider the NAV when transmitting the frame after PIFS from the previous PPDU.

[0245] Referring to FIG. 20, for STA2, the NAV may be set based on a MU-RTS frame or a modified MU-RTS frame. For example, an intra-BSS NAV may be set. Alternatively, for STA2, the NAV may be set based on an intra-BSS frame. Alternatively, for STA2, the NAV may be set based on a frame transmitted by the combined AP. In this embodiment, the NAV may be a general term for such NAVs. STA1 can perform TXOP sharing with STA2. STA2 can receive TXOP sharing by means of a modified MU-RTS frame. When transmitting a frame in a shared TXOP, STA2 can transmit the frame regardless of the NAV. At this time, according to one embodiment, the frame to be transmitted may be a frame transmitted immediately after a CTS frame transmitted immediately after the received modified MU-RTS frame. According to still other embodiments, at this time, the frame to be transmitted may be a frame transmitted immediately after the received modified MU-RTS frame. Also, according to one embodiment, the frame transmitted by STA2 may be a frame sent to the STA that transmitted the modified MU-RTS frame. That is, the RA field of the frame to be transmitted may be set to the value of the TA field of the received modified MU-RTS frame. Alternatively, the RA field of the frame to be transmitted may be set to the MAC address of the AP. According to other embodiments, the frame transmitted by STA2 may be a frame transmitted to STA3. Also, the statement of transmitting a frame immediately afterwards may mean a case where 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 the sharing of TXOP and the transmission of CTS frames 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 above-described content can be omitted from the description.

[0248] According to an embodiment of the present invention, in order to solve the problem of difficulty in transmitting frames with a shared TXOP in consideration of the NAV, the frame sequence can be continued so that the condition for transmitting a response regardless of the 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 performs TXOP sharing receives a frame including the MAC address of the STA that receives TXOP sharing after transmitting the modified MU-RTS frame, it can be determined that the shared TXOP allocation has occurred successfully.

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

[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, as described with reference to FIG. 21, a further method for setting the RA field of the CTS frame for transmitting the CTS-to-self frame may be defined. For example, it is possible to set the MAC address of the STA transmitting the CTS frame in the RA field of the CTS frame transmitted as a response to the modified MU-RTS frame.

[0252] According to an embodiment of the present invention, a STA that has received TXOP sharing may be able to perform recovery within the shared TXOP. That is, a STA that has received TXOP sharing can perform recovery when a frame it has transmitted fails within the shared TXOP. For example, a STA that has received TXOP sharing can transmit a frame at a time point that is only PIFS slower when a frame it has transmitted 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, when 1) a STA that 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, it can perform recovery. Also, when a STA that has received TXOP sharing transmits a frame that is not the first CTS frame after receiving a modified MU-RTS frame, if the frame that is not the CTS frame fails, it can perform a recovery operation. For example, the TXOP holder may not be able to perform a recovery operation when the first transmitted frame in the sequence fails, and at this time, the TXOP may not have been obtained. However, a STA that has received TXOP sharing can also perform a recovery operation when a frame that is not 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 retransmit the frame when it fails to receive the DL frame shown in the drawing after transmitting the UL frame. 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 TXOP sharing according to an embodiment of the present invention.

[0255] As described with reference to FIG. 19, whether it is a modified MU-RTS frame may be determined 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 may be based on a value that is not assigned as an actual AID. The already set AID12 subfield value may be the 12 LSBs of a value that is not assigned as an actual AID. For example, the already set AID12 subfield value may be 2007.

[0256] Also, the extended functions described above may include, for example, an extended 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 a 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 described 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 the user information field including the previously set AID12 subfield value as the user information field. That is, when the received trigger frame does not include any user information field or includes only the user information field including the previously set AID12 subfield value as the user information field, the trigger frame can be determined as a modified MU-RTS frame. Alternatively, when the received MU-RTS frame does not include any user information field or includes only the user information field including the previously set AID12 subfield value as the user information field, 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 pre-set value. At this time, the pre-set value may be a value not assigned as an AID. Also, the pre-set value may be a value different from the 12 LSBs of the AID of the STA having the RA field value of the modified MU-RTS frame as the MAC address. For example, the pre-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 received by the STA is set as the MU-RTS frame, if the trigger frame does not include any user information fields or only includes the user information field including the AID12 subfield of the pre-set value, the trigger frame can be determined as the modified MU-RTS frame.

[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 may be able to reset the set NAV. For example, when the NAV is set based on an RTS frame or a MU-RTS frame, it may be possible to reset the NAV. More specifically, when the NAV is set based on an RTS frame or a MU-RTS frame, it may be possible to reset the NAV if the PPDU reception cannot be successfully started at 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 be started 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, when the NAV is set based on an RTS frame or a MU-RTS frame, it 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 greater 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 TXOP field included in the preamble of the PPDU.

[0263] Also, in an embodiment of the present invention, when the PPDU reception is successfully started, the PHY-RXSTART.indication primitive can be received. Or, when the PPDU reception is successfully started, the PHY-RXSTART.indication primitive can 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 the PPDU. Also, receiving a valid start of the PPDU can mean receiving a valid PHY header. Also, 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 state for 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 state for the length of the PPDU or the length indicated by the PPDU preamble. Also, the PHY-RXEND.indication may be generated when the PPDU reception is completed.

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

[0265] According to one embodiment, the NAV timeout period can be based on at least one of the following. 1) CTS_Time 2) aSIFSTime 3) aRxPHYStartDelay 4) aSlotTime

[0266] According to one embodiment, CTS_Time can be calculated based on a predefined rate. That is, CTS_Time can be the length of the CTS frame calculated based on the predefined rate. Or, that is, CTS_Time can be the length of the PPDU including the CTS frame calculated based on the predefined rate. For example, the predefined rate can be 6 Mbps. For example, CTS_Time can be calculated based on a data rate of 6 Mbps. Or, the predefined rate can be the rate of the RTS frame or MU-RTS frame that sets the NAV. Or, the predefined rate can be the rate indicated by the RTS frame or MU-RTS frame that sets the NAV.

[0267] According to one embodiment, aSIFSTime can be the SIFS length. For example, aSIFSTime can be 10 us when operating in the 2.4 GHz band. For example, aSIFSTime can be 16 us when operating in the 5 GHz band or 6 GHz band.

[0268] 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 from the start of the PPDU to determine the PPDU format. 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 the HT-mixed format. Also, aRxPHYStartDelay may be 24 us for an HT PPDU in the 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.

[0269] According to one embodiment, the NAV timeout period may be ((2*aSIFSTime)+(CTS_Time)+aRxPHYStartDelay+(2*aSlotTime)).

[0270] According to an embodiment of the present invention, the RTS frame may be a frame that instructs a CTS frame. Alternatively, the RTS frame may be a frame that instructs 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 a STA is the address of the STA, it is possible to respond to the RTS frame with a CTS 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 the frame including the Type subfield and the Subtype subfield is an RTS frame. For example, the RTS frame may be a Control frame.

[0271] 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 the frame including the Type subfield and the Subtype subfield is a CTS frame. For example, the CTS frame may be a Control frame.

[0272] Referring to the first sequence of 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 CS (carrier sense) 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, it may not be possible to release the NAV set by STA3.

[0273] 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 be impossible to respond with a CTS frame. Or, although STA2 successfully receives the RTS frame or the MU-RTS frame, it may be impossible to respond with a CTS frame based on the CS result. In such a case, the frame sequence sent by STA1 to STA2 may not continue.

[0274] 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 be impossible for STA3 to receive a CTS frame sent by STA2 or a frame sent by STA1 to STA2. In such a case, STA3 does not have to receive a PHY-RXSTART.indication primitive within the NAVTimeout period. Therefore, the NAV set by STA3 can be released. This can solve the problem that STA3 maintains the NAV and cannot access the channel even though the sequence is not continuing.

[0275] FIG. 24 is a diagram showing the sharing of TXOP and the NAV timeout according to an embodiment of the present invention.

[0276] Referring to FIG. 24, as described above, STA1 can perform TXOP sharing with STA2. STA1 can be the STA that performs TXOP sharing, and STA2 can be the STA that receives TXOP sharing. STA1 can send the first frame of the sequence to STA2. Referring to FIG. 24, the first frame of the sequence that STA1 sends to STA2 can be a MU-RTS frame. Also, a CTS frame that is a response to the MU-RTS frame may be sent.

[0277] For example, a CTS frame may be transmitted from a STA including STA2. STA1 can obtain a TXOP. Also, STA3 may not have successfully received 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 TXOP sharing sequence described above, 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 can transmit a frame. Also, STA3 may not be able to receive a frame or PPDU from STA2. For example, STA3 may be in a hidden position from STA2. For example, the power transmitted by STA2 may not be sufficient for STA3 to receive. 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 not determined based on the CTS_Time. That is, when STA2 transmits a frame after transmitting a CTS frame, the NAV timeout 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 NAV timeout period should end while the frame is being transmitted. Therefore, STA3 may be able to cancel the NAV. If STA3 cancels the NAV, STA3 may connect to the channel and interfere with the sequence in the shared TXOP.

[0278] FIG. 25 is a diagram showing TXOP sharing and NAV timeout according to still another embodiment of the present invention.

[0279] Referring to FIG. 25, when the TXOP is shared by the AP, other STAs (third STAs) that are not the STAs with the TXOP 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 with the shared TXOP 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.

[0280] Specifically, based on whether the trigger frame (for example, MU-RTS frame) transmitted from the AP is a modified MU-RTS frame or a MU-RTS TXS trigger frame for sharing the TXOP, the NAV timeout for releasing the TXOP may be allowed or not allowed. That is, depending on whether it is a generally set TXOP or a TXOP in which all or part of the TXOP set by the AP is shared, it may be determined whether the NAV timeout for other STAs that are not the STAs with the set TXOP to release the set TXOP is allowed.

[0281] For example, when the NAV is set based on an 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, if the MU-RTS frame is not a modified MU-RTS frame, or if the PPDU reception cannot be successfully started within the NAVTimeout period, it may be possible to release the NAV.

[0282] 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 the STA sets the NAV based on the 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 may not be able to cancel the NAV even if it fails to successfully start receiving the PPDU within the NAVTimeout period.

[0283] That is, if the last frame 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 NAVTimeout expires.

[0284] Whether the received MU-RTS frame is a modified MU-RTS frame may 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.

[0285] According to the embodiments of the present invention, after the STA sets the NAV based on the modified MU-RTS frame, the problem of interfering with the sequence of the shared TXOP can be prevented by performing the NAV timeout operation, which solves the problem described with reference to FIG. 24.

[0286] In addition, such an embodiment can be performed by terminals after the 802.11be standard (including terminals of subsequent standards including the EHT standard), and terminals of the 802.11ax standard (HE STA) may not be able to perform it. Even if the HE STA cannot perform this, the probability of the problems described in the above embodiments occurring can be reduced.

[0287] Referring to FIG. 25, STA1, STA2, and STA3 may exist. Also, STA1 can send a MU-RTS frame to STA2. For example, STA1 can send 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 send a CTS frame. Also, STA3 can set the NAV based on the MU-RTS frame. However, since STA2 was unable to send a CTS frame, STA3 may not have successfully received the PPDU during the NAVTimeout period. In this case, based on the NAV timeout operation, STA3 can cancel the set NAV. This may be because the frame that caused STA3 to set the NAV is a MU-RTS frame that is not a modified MU-RTS frame.

[0288] Also, 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 in response to the modified MU-RTS frame. For example, it may be because the response transmitted 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 within the NAVTimeout period. This may be because STA2 transmits a frame after transmitting a CTS frame after the modified MU-RTS frame. Or, this may be because STA2 transmits a frame longer than the CTS frame after the modified MU-RTS frame. Or, this may be because STA2 transmits a PPDU longer than the PPDU including the CTS frame after the modified MU-RTS 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.

[0289] FIG. 26 is a diagram showing the sharing of TXOP and the NAV timeout according to still another embodiment of the present invention.

[0290] The embodiment of FIG. 26 may be for solving the problems described with reference to FIGS. 23 and 24. Also, the above-described content may be omitted.

[0291] According to an embodiment of the present invention, the NAV timeout period may be determined to be different based on whether the MU-RTS frame is a modified MU-RTS frame. For example, the CTS_Time may be determined to be different 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 can start at the same time. That is, it may be started 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 required to transmit the CTS frame at 6 Mbps.

[0292] According to an embodiment of the present invention, when the STA sets the NAV based on the modified MU-RTS frame, it may be possible to release the NAV when the PPDU reception fails successfully with the extended NAVTimeout period. When the STA sets the NAV based on the modified MU-RTS frame, the NAV may not be released even when the PPDU reception cannot be successfully started with the NAVTimeout period described in FIG. 23.

[0293] Also, when the STA sets the NAV based on a MU-RTS frame that is not a modified MU-RTS frame, it may be possible to release the NAV when the PPDU reception cannot be successfully started within the NAVTimeout period described in FIG. 23.

[0294] 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. As yet another example, 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 that receives TXOP sharing among the User Info fields shown in FIG. 16.

[0295] Also, the STA that has received the TXOP sharing can transmit the 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.

[0296] 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 be unable to respond to the MU-RTS frame. Therefore, STA2 may be unable 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 been able to successfully start receiving the PPDU within 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 required to transmit the CTS frame.

[0297] In addition, STA1 can send a modified MU-RTS frame. In FIG. 26, 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 NAV based on the modified MU-RTS frame. However, there may be a case where STA3 fails to receive the response sent by STA2 in response 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 within the NAVTimeout period described in FIG. 23. However, in such a case, STA3 can successfully start receiving the PPDU within the extended NAVTimeout period. Therefore, STA3 does not have to perform the NAV timeout operation. The fact that STA3 can wait for the extended NAVTimeout period without performing the NAV release operation when the NAVTimeout period described in FIG. 23 has elapsed may be because the frame that caused STA3 to set the NAV is the MU-RTS frame which is the modified MU-RTS frame.

[0298] If STA2, which has received the modified MU-RTS frame, fails to respond, STA1 can perform a recovery operation. Therefore, STA3 can successfully start receiving the PPDU before performing the NAV timeout operation.

[0299] Alternatively, when STA2, which has received the modified MU-RTS frame, fails to respond, the sequence of the shared TXOP may be interrupted. In this case, STA3 can solve the problem that the NAV is unnecessarily set and the channel cannot be connected when no actual frame exchange occurs by performing the NAV timeout operation.

[0300] In the case of TXOP sharing, the problem and solution in which it is difficult for a scheduled STA that has received part or all of the TXOP shared by the AP to transmit according to the set NAV were described with reference to FIG. 20. The solution 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 may be used interchangeably.

[0301] 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.

[0302] 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 the 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 the 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 the TXOP, the STA sets the NAV based on the received MU-RTS frame.

[0303] Also, in TXOP sharing, a scheduled STA does not have to set the NAV based on a frame received within the shared TXOP.

[0304] At this time, within the shared TXOP, even if the duration of the shared TXOP is not fully utilized, it can represent until the shared TXOP ends. When the scheduled STA of the shared TXOP transmits a PPDU and the PPDU contains 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 when, since the TXOP sharing is set, the scheduled STA of the TXOP sharing transmits a PPDU that contains only frames that do not require an immediate response. When the scheduled STA of the TXOP sharing signals the end of the shared TXOP, the shared TXOP may end. Therefore, within the shared TXOP, it can be from when the TXOP sharing is set until the scheduled STA of the TXOP sharing signals the end of the shared TXOP. Also, within the TXOP, it can be from when the TXOP sharing is set until the duration of the shared TXOP has elapsed. Or, when the STA that received the TXOP sharing (or the STA that shared the TXOP) transmits and receives a signaling indicating that the shared TXOP has ended, the shared TXOP may end. In this case, whether the duration of the shared TXOP is the same as the duration of the TXOP used by the AP for sharing (the TXOP acquired by the first frame of the AP), 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 is the same as the duration of the TXOP, if the shared TXOP ends, the TXOP also ends together, but when the duration of the shared TXOP is shorter than the duration of the TXOP, the TXOP may be maintained even if the shared TXOP ends.

[0305] 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 the TXOP sharing is set until the duration of the shared TXOP has elapsed.

[0306] 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 has received TXOP sharing 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, a STA that has received TXOP sharing before the period set by MU-RTS within the shared TXOP can interrupt the TXOP sharing by transmitting signaling to request an interruption of the TXOP sharing. For example, when a non-AP STA has received sharing of all or part of a TXOP from the AP, if there is no PPDU to be transmitted (or pending), the non-AP STA can interrupt the TXOP sharing by transmitting signaling to end the TXOP sharing to the AP to end the shared TXOP. The point in time when the TXOP sharing is interrupted may be one of 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 earlier than the period during which the TXOP set by the MU-RTS frame is shared, the non-AP STA can ignore the NAV set only until the point in time when the TXOP sharing ends.

[0307] At this time, the STA that has set TXOP sharing can also transmit frames regardless of NAV. In the embodiment of FIG. 27, 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. The second STA (STA2) performs frame exchange within the shared TXOP. The first STA (STA1) can set 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 NAV based on the frame transmitted by the third STA (STA3) to the second STA (STA2). Also, the first STA (STA1) can set NAV based on the frame transmitted by the second STA (STA2) to the third STA (STA3). When the first STA (STA1) sets NAV in this way, it may be difficult to transmit frames within the TXOP to which the shared TXOP is allocated. For example, when the first STA (STA1) attempts to transmit a frame after the shared TXOP ends, it may be impossible to transmit the frame 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 be unable to transmit the frame due to the set NAV.

[0308] A STA configured with TXOP sharing can transmit frames regardless of the NAV within the TXOP acquired by the STA. Further, in other specific embodiments, a STA configured with TXOP sharing can transmit frames regardless of the NAV within the TXOP acquired since the shared TXOP ended. A STA configured with TXOP sharing may be the STA that transmitted the MU-RTS frame for configuring TXOP sharing or the TXOP holder.

[0309] 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, before the interval set by MU-RTS, the STA that received TXOP sharing can interrupt the sharing of the TXOP by transmitting signaling for requesting interruption of the sharing of the TXOP. For example, when a non-AP STA receives sharing of all or part of the TXOP from an AP, if there is no (or pending) PPDU to be transmitted, the non-AP STA can transmit signaling for ending TXOP sharing to the AP to end the shared TXOP and interrupt the sharing of the TXOP. The point in time when the TXOP sharing is interrupted may be one of 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 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 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.

[0310] In the foregoing embodiments, that the STA with TXOP sharing transmits a frame regardless of the NAV can indicate that the frame is transmitted regardless of the NAV set based on the frames exchanged by the scheduled STAs within the TXOP sharing. When the STA with TXOP sharing transmits a frame regardless of the NAV set based on a frame not exchanged by the scheduled STA within the TXOP sharing, it may interfere with the frame exchange of other STAs. Also, the STA can determine whether a frame is a frame exchanged by the scheduled STA 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 STA 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 STA within the TXOP sharing. Also, the STA can determine whether a frame is a frame exchanged by the scheduled STA 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 STA 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 the frame included in the PPDU as 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.

[0311] In still other specific embodiments, when a STA configured with TXOP sharing transmits regardless of NAV, only physical CS, e.g., CCA, can be used as carrier sensing (CS) when transmitting a frame. Thus, the STA does not have to perform virtual CS.

[0312] In this specification, setting NAV may be used interchangeably with updating NAV. Also, in this specification, NAV may include at least one of Intra-BSS NAV or basic NAV. Also, unless otherwise specifically mentioned about the type of NAV, NAV can refer to Intra-BSS NAV. Also, in this specification, when a STA sets NAV based on a certain frame, it may include setting NAV based on the PPDU including the frame. Thus, in this specification, when a STA does not set NAV based on a certain frame, it may include not setting NAV based on the PPDU including the frame.

[0313] The MU-RTS frame for setting TXOP sharing can indicate the scheduled STAs of TXOP using a MAC address, e.g., the RA field or the User Info field. Setting NAV based on the duration information of a frame or PPDU can indicate that the last set NAV is set based on the duration information of the frame or PPDU.

[0314] 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.

[0315] 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 sets 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 be not after but earlier than the end time of the shared TXOP. In this case, since 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, the value indicated by the duration information included in the PPDU may be set based on the shared TXOP.

[0316] In yet other specific embodiments, a STA that sets a shared TXOP may not need to set the NAV based on the frames exchanged by the scheduled STA for TXOP sharing.

[0317] A STA that sets a shared TXOP within the shared TXOP may not need to transmit a trigger frame. This is because when a STA that sets a shared TXOP within the shared TXOP transmits a trigger frame, the frame triggered by the trigger frame may overlap with the frame exchange of the scheduled STA. Also, when a STA that sets a shared TXOP within the shared TXOP transmits a trigger frame to the scheduled STA, the scheduled STA may need 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.

[0318] In the foregoing embodiments, the trigger frame that a STA with a shared TXOP cannot transmit may be the remaining trigger frames except for the trigger frame for only the scheduled STA of TXOP sharing. Therefore, a STA with a shared TXOP can transmit a trigger frame only to the scheduled STA of TXOP sharing within the shared TXOP. For example, a STA with a shared TXOP can transmit a MU-RTS frame for setting TXOP sharing to extend the shared TXOP. At this time, the 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, the STA that has received the MU-RTS frame for setting TXOP sharing can start frame exchange without transmitting a CTS frame.

[0319] In this specification, the operations performed with a shared TXOP may be operations in which the shared TXOP is utilized by the scheduled STA of TXOP sharing. The operations performed with 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 the scheduled STA of TXOP sharing transmitting a frame within the shared TXOP. At this time, the response frame to the MU-RTS frame for setting TXOP sharing may be a CTS frame.

[0320] Describe the signaling for TXOP co - operation. A STA can signal whether it can operate as a scheduled STA for TXOP sharing. At this time, the STA can use the EHT Capabilities element to signal whether it can operate as a scheduled STA for TXOP sharing. 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 set up TXOP sharing can send a MU - RTS frame for setting up 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 set up TXOP sharing may not be able to send a MU - RTS frame for setting up TXOP sharing to a STA that has signaled that it cannot operate as a scheduled STA for TXOP sharing.

[0321] 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 can 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.

[0322] In the foregoing embodiment, 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 referred to as the TXOP Sharing Mode subfield. The TXOP Sharing Mode subfield may be a subfield of the 21st bit (B20) to the 22nd bit (B21) of the Common Info field in FIG. 16.

[0323] A method for ending TXOP sharing is described with reference to FIG. 28.

[0324] FIG. 28 shows an example of the present invention in which a STA ends TXOP sharing.

[0325] The scheduled STA for TXOP sharing can signal the end of TXOP sharing. When the STA that set the TXOP sharing receives the end signaling of the TXOP sharing, the STA that set the TXOP sharing can become the TXOP holder. Also, when the STA that set the TXOP sharing receives the end signaling of the TXOP sharing, the STA that set the TXOP sharing can transmit a frame or a PPDU. Specifically, when the STA that set the TXOP sharing receives the end signaling of the TXOP sharing, even within the shared TXOP, the STA that set the TXOP sharing can transmit a frame or a PPDU. Also, when the scheduled STA for TXOP sharing signals the end of the TXOP sharing, the scheduled STA for TXOP sharing may not be able to transmit any frame or any PPDU within the remaining shared TXOP.

[0326] 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 receives 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 receives 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.

[0327] 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.

[0328] 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. It may be impossible to transmit the SRS Control subfield to an STA that has signaled that it does not support the operation with respect to the SRS Control subfield. The STA can transmit the SRS Control subfield to an STA that has signaled that it supports the operation with respect to the SRS Control subfield.

[0329] 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 whose Shared TXOP Termination field value is 1, the STA can determine that the TXOP sharing ends.

[0330] In still other specific embodiments, a frame having a predefined setting can signal the end of TXOP sharing. At this time, the frame having the predefined setting may be a Qos Null frame. Specifically, the frame having the predefined setting may be a QoS Null frame that does not include the A-Control subfield. Also, the frame having the predefined setting may be a QoS Null frame that does not include the SRS Control subfield. The scheduled STA for TXOP sharing can transmit a frame having the predefined setting to signal the end of TXOP sharing. Also, when the STA that sets the TXOP sharing receives a frame having the predefined setting, the STA that sets the TXOP sharing can determine that the TXOP sharing ends.

[0331] A scheduled STA sharing a TXOP may send a TXOP sharing termination signaling, but the STA that set up the TXOP sharing may not be able to receive the signaling. At this time, the scheduled STA sharing the TXOP may determine that the TXOP sharing has ended and does not need to send a frame. Also, the STA that set up the TXOP sharing may determine that the TXOP sharing has not ended and does not need to send a frame.

[0332] In a specific embodiment, when the scheduled STA of the TXOP sharing that signaled the end of the TXOP sharing receives a response to the signaling, the scheduled STA of the TXOP sharing can determine that the TXOP sharing has ended. At this time, the scheduled STA of the TXOP sharing does not have to transmit a frame after determining that the TXOP sharing has ended. The response to the end signaling of the TXOP sharing may be an immediate response. Also, the response to the end signaling of the TXOP sharing may be an ACK. However, such an embodiment may be applied only when the Ack policy of the end signaling of the TXOP sharing is set to require an immediate response. Specifically, when the Ack policy of the end signaling of the TXOP sharing requires an immediate response, when the scheduled STA of the TXOP sharing that signaled the end of the TXOP sharing receives a response to the signaling, the scheduled STA of the TXOP sharing can determine that the TXOP sharing has ended. When the Ack policy of the end signaling of the TXOP sharing does not require an immediate response, for example, No ACK, even if the scheduled STA of the TXOP sharing that signaled the end of the TXOP sharing does not receive a response to the signaling, the scheduled STA of the TXOP sharing can determine that the TXOP sharing has ended. At this time, the scheduled STA of the TXOP sharing can determine that the TXOP sharing has ended when transmitting the end signaling of the TXOP sharing. Also, when the transmission of the end signaling of the TXOP sharing fails, an error recovery operation may be performed. Specifically, the scheduled STA of the TXOP sharing can perform an error recovery operation. Also, the STA that set the TXOP sharing can perform an error recovery operation.

[0333] 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 (STA1) 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.

[0334] 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.

[0335] As described above, it may not be possible to send an SRS Control subfield to a STA that has signaled that it does not support operations on the SRS Control subfield. When the end of TXOP sharing is signaled by the SRS Control subfield, a STA that has signaled that it does not support operations on the SRS Control subfield may not be able to receive the end-of-TXOP sharing signaling. Therefore, the scheduled STA for TXOP sharing can also send an SRS Control subfield that signals the end of TXOP sharing to a STA that has signaled 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 send an SRS Control subfield in which the value of the TXOP Termination subfield is 0 to a STA that has signaled that it does not support operations on the SRS Control subfield. Also, the restriction that an SRS Control subfield cannot be sent to a STA that has signaled that it does not support operations on the SRS Control subfield may apply only when the SRS Control subfield is sent outside the shared TXOP.

[0336] 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 the frame that includes the SRS Control subfield.

[0337] 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.

[0338] 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.

[0339] Alternatively, a STA that receives an SRS Control subfield within a shared TXOP may not need to 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 may be able to respond regardless of the duration information (PPDU Response Duration subfield value) included in the SRS Control subfield.

[0340] According to an embodiment of the present invention, the modified MU-RTS frame may not be the first frame within the TXOP. For example, the TXOP holder may not send a modified MU-RTS frame to obtain the TXOP and may send other frames instead. Thereby, the 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, but by allowing a frame transmission to exist earlier than the modified MU-RTS frame in the TXOP, setting the NAV based on an RTS frame or a MU-RTS frame can be reduced. Also, the duration information included in the modified MU-RTS frame may not increase the TXOP.

[0341] FIG. 29 shows a method of signaling the format of a TB PPDU that responds to a trigger frame using the Common Info field and the Special User Info field included in the trigger frame according to an embodiment of the present invention.

[0342] In an embodiment of the present invention, a station that receives a trigger frame can determine the format of a TB PPDU based on the User Info field included in the trigger frame. Specifically, a specific User Info field included in the trigger frame can indicate the format of the TB PPDU transmitted as a response to the trigger frame. For the convenience of explanation, at this time, the specific User Info field is referred to as the Special User Info field.

[0343] The AID12 subfield of the Special User Info field may be set to a specified value. At this time, the specified value may be 2007. Also, it may be a value that the AP does not assign as an AID (association ID). Further, the format of the Special User Info field may be different from the format of the User Info field that is not the Special User Info field. The format of the subfields included in the Special User Info field and the format of the subfields included in the User Info field that is not the Special User Info field may be different. At this time, the format of the AID12 subfield included in the Special User Info field and the format of the AID12 subfield included in the User Info field that is not the Special User Info field may be the same. Therefore, the first 12 bits of the Special User Info field, that is, the value of AID12, may be set to the specified value. Thereby, the HE station can also parse a trigger frame including the Special User Info field without error.

[0344] Also, the trigger frame may include a sub-field that indicates whether the trigger frame includes a Special User Info field. For the sake of convenience of explanation, the sub-field that indicates whether the trigger frame includes a Special User Info field is referred to as the Special User Info Field Present field. Specifically, the Common Info field of the trigger frame may include a Special User Info Field Present sub-field. At this time, the 56th bit (B55) of the Common Info field may be the Special User Info Field Present sub-field. In a specific embodiment, when the value of the Special User Info Field Present sub-field is 1, the trigger frame may not include a Special User Info field. Also, when the value of the Special User Info Field Present sub-field is 0, the trigger frame may include a Special User Info field. This is because the 56th bit of the Common Info field of the legacy trigger frame is basically (default) set to 1. The station that receives the trigger frame can determine whether the trigger frame includes a Special User Info field based on the Special User Info field. When the value of the Special User Info Field Present sub-field of the trigger frame received by the station is 1, the station can determine that the trigger frame does not include a Special User Info field. Also, when the value of the Special User Info Field Present sub-field of the trigger frame received by the station is 0, the station can determine that the trigger frame includes a Special User Info field.As in the foregoing embodiments, when the Special User Info Field Present subfield is included in the trigger frame, even if an unassociated station receives the trigger frame, it can be determined whether the Special User Info field is included in the trigger frame.

[0345] The trigger frame may include the Special User Info field before the User Info fields that are not Special User Info fields. Specifically, the trigger frame may include the User Info field immediately after the Common Info field. The station can determine the format of the TB PPDU, which is a response to the trigger frame, based on whether the received trigger frame of the station includes the Special User Info field. When the trigger frame received by the station includes the Special User Info field, the station can transmit an EHT TB PPDU as a response to the trigger frame. When the trigger frame received by the station does not include the Special User Info field, the station can transmit an HE TB PPDU as a response to the trigger frame. As described above, the trigger frame may include the Special User Info Field Present subfield. At this time, the station can determine the format of the TB PPDU, which is a response to the trigger frame, based on the value of the Special User Info Field Present field of the trigger frame received by the station. When the value of the Special User Info Field Present field of the trigger frame received by the station is 0, the station can transmit an EHT TB PPDU as a response to the trigger frame. When the value of the Special User Info Field Present field of the trigger frame received by the station is 1, the station can transmit an HE TB PPDU as a response to the trigger frame.

[0346] When the trigger frame includes a User Info field that is an EHT variant, the trigger frame may always include a Special User Info field. When the trigger frame does not include a Special User Info field, it may not be allowed for the trigger frame to include a User Info field that is an EHT variant.

[0347] The method by which a User Info field that is an EHT variant indicates RU may be different from the method by which a User Info field that is an HE variant indicates RU. Specifically, the method by which the RU Allocation subfield of a User Info field that is an EHT variant indicates RU may be different from the method by which the RU Allocation subfield of a User Info field that is an HE variant indicates RU. For example, the RU Allocation subfield of a User Info field that is an EHT variant may indicate an RU index for the User Info field that is an EHT variant. Also, the RU Allocation subfield of a User Info field that is an HE variant may indicate an RU index for the User Info field that is an HE variant. A User Info field that is an EHT variant can indicate the RUs allocated to the station corresponding to the User Info field using the RU Allocation subfield and the PS160 subfield.

[0348] The RU Allocation subfield may be located immediately after the AID12 subfield, as described in FIG. 16. Also, the RU Allocation subfield may be an 8-bit field. The PS160 subfield can indicate in which subchannel the RU indicated by the RU Allocation subfield of the User Info field containing the PS160 subfield is located. At this time, the bandwidth of the subchannel may be 160 MHz. Specifically, the PS160 subfield can indicate whether it is located in the RU primary 160 MHz channel or the secondary 160 MHz channel indicated by the RU Allocation subfield of the User Info field containing the PS160 subfield. Also, the PS160 subfield may be located immediately before the Trigger Dependent User Info subfield. The PS160 subfield is a 1-bit field and may be the 40th bit (B39) of the RU Allocation subfield.

[0349] The User Info field, which is an HE variant, can indicate the RU allocated to the station corresponding to the User Info field using the RU Allocation subfield.

[0350] In the embodiment of FIG. 29, the station that receives the trigger frame can determine a subfield that indicates the format of the TB PPDU transmitted as a response to the trigger frame on a pre-specified channel, and the format of the subfield of the subfield that indicates the format of the TB PPDU transmitted as a response to the trigger frame based on the Special User Info field. At this time, the pre-specified channel may be the primary 160 MHz channel. For convenience of explanation, the subfield that indicates the format of the TB PPDU transmitted as a response to the trigger frame is referred to as the HE / EHT P160 subfield. When the HE / EHT P160 subfield indicates that the format of the TB PPDU transmitted as a response to the trigger frame on the primary 160 MHz channel is the EHT TB PPDU, the station that receives the trigger frame can transmit the EHT TB PPDU as a response to the trigger frame regardless of the position of the RU assigned to the station. At this time, the value of the HE / EHT P160 subfield may be 0. Also, when the HE / EHT P160 subfield indicates that the format of the TB PPDU transmitted as a response to the trigger frame on the primary 160 MHz channel is the EHT TB PPDU, the trigger frame may always include the Special User Info field.

[0351] When the HE / EHT P160 subfield indicates that the format of the TB PPDU transmitted as a response to the trigger frame on the primary 160 MHz channel is an HE TB PPDU, the station that receives the trigger frame can determine the format of the TB PPDU transmitted as a response to the trigger frame according to the position of the RU assigned to the station. At this time, the value of the HE / EHT P160 subfield may be 1. Specifically, when the HE / EHT P160 subfield indicates that the format of the TB PPDU transmitted as a response to the trigger frame on the primary 160 MHz channel is an HE TB PPDU and the RU assigned to the station that receives the trigger frame is not included in the primary 160 MHz, the station can transmit an EHT TB PPDU as a response to the trigger frame. Also, when the HE / EHT P160 subfield indicates that the format of the TB PPDU transmitted as a response to the trigger frame on the primary 160 MHz channel is an HE TB PPDU and the RU assigned to the station that receives the trigger frame is included in the primary 160 MHz, the station can transmit an HE TB PPDU as a response to the trigger frame. At this time, the station can determine whether the RU assigned to the station is included in the primary 160 MHz based on the value of the PS160 subfield.

[0352] The HE / EHT P160 subfield may be included in the Common Info field. Specifically, the HE / EHT P160 subfield may be the 56th bit (B55) of the Common Info field. Also, the HE / EHT P160 subfield may be included in the Common Info field which is an EHT variant, and the PS160 field may be included in the User Info field which is an EHT variant. Therefore, when the trigger frame includes the Special User Info field, the trigger frame may include the HE / EHT P160 subfield and the PS160 field. FIG. 29 shows the Common Info field and the Special User Info field to which such an embodiment is applied.

[0353] The aforementioned EHT TB PPDU may be replaced with a NEXT TB PPDU. Therefore, when the EHT TB PPDU is indicated as the format of the TB PPDU in the aforementioned embodiment, the NEXT TB PPDU or the EHT TB PPDU may be transmitted as the TB PPDU. At this time, the station that has received the trigger frame can determine which PPDU of the EHT TB PPDU and the NEXT TB PPDU to transmit as a response to the trigger frame based on the Format Identifier subfield. Specifically, the station can transmit the TB PPDU according to the format of the TB PPDU indicated by the Format Identifier subfield.

[0354] The Special User Info field may contain information necessary when transmitting an EHT TB PPDU as a response to a trigger frame. Specifically, the Special User Info field may contain information necessary to set the PPDU signaling field of the EHT TB PPDU transmitted as a response to the trigger frame. At this time, the PPDU signaling field may be the U-SIG field. In FIG. 29, the Special User Info field may include an AID12 subfield, a PHY Version ID subfield, a UL Bandwidth Extension subfield, a Spatial Reuse1 subfield, a Spatial Reuse 2 subfield, a U-SIG Disregard And Validate subfield, a Reserved subfield, and a Trigger Dependent User Info field subfield. At this time, the AID12 subfield may be a 12-bit field. Also, the PHY Version ID subfield may be a 2-bit field. The UL Bandwidth Extension subfield may be a 2-bit field. Also, the Spatial Reuse1 subfield may be a 4-bit field. Also, the Spatial Reuse 2 subfield may be a 4-bit field. Also, the U-SIG Disregard And Validate subfield may be a 12-bit field. Also, the Reserved subfield may be a 3-bit field. Also, the Trigger Dependent User Info field subfield may have a variable length. The specific format of the Special User Info field may be as shown in FIG. 29.

[0355] The PHY Version ID subfield may be the aforementioned Format Identifier subfield, PHY version identifier subfield, or PHY version subfield. When the value of the PHY version ID subfield is set to 0, the PHY version ID subfield can indicate the EHT physical layer. A station that has received a trigger frame can set the U-SIG field of the TB PPDU transmitted as a response to the trigger frame based on the Special User Info field. Specifically, a station that has received a trigger frame can set the value of the subfield included in the Special User Info field to the value of the subfield of the U-SIG field of the TB PPDU. At this time, the subfield of the U-SIG field may include the PHY Version ID subfield, Spatial Reuse1 subfield, Spatial Reuse 2 subfield, and U-SIG Disregard And Validate subfield. Also, a station that has received a trigger frame can set the bandwidth (BW) subfield of the U-SIG field of the TB PPDU based on the UL Bandwidth Extension subfield of the Special User Info field and the UL BW subfield of the Common Info field.

[0356] In addition, a station that has received a trigger frame can perform a spatial reuse (SR) operation based on the Spatial Reuse 1 subfield or the Spatial Reuse 2 subfield. Specifically, when a station that has received a trigger frame determines that the trigger frame is an Inter-BSS frame, the station can perform the SR operation. The SR operation may be a type of channel access. When a station performs the SR operation, the station can transmit a PPDU based on the information included in the trigger frame and the transmission power of the PPDU to be transmitted in the SR operation.

[0357] The UL Bandwidth Extension subfield may be a field used when the frequency bandwidth indicated by the trigger frame exceeds 160 MHz. The UL Bandwidth Extension subfield can indicate 320 MHz. The UL BW subfield of the Common Info field can indicate that the frequency bandwidth indicated by the trigger frame is one of 20 MHz, 40 MHz, 80 MHz, and 160 MHz. The values 0, 1, 2, and 3 of the UL BW subfield can indicate 20 MHz, 40 MHz, 80 MHz, and 160 MHz, respectively.

[0358] In addition, the trigger frame can indicate the frequency bandwidth using the UL BW subfield of the Common Info field and the UL Bandwidth Extension subfield of the Special User Info field. Therefore, a station receiving the trigger frame can determine the frequency bandwidth indicated by the trigger frame based on the UL BW subfield of the Common Info field and the UL Bandwidth Extension subfield of the Special User Info field. The UL BW subfield of the Common Info field and the UL Bandwidth Extension subfield of the Special User Info field can indicate 20 MHz, 40 MHz, 80 MHz, 160 MHz, and 320 MHz. At this time, the UL BW subfield and the UL Bandwidth Extension subfield can distinguish and indicate the 320 MHz frequency band as 320 - 1 MHz and 320 - 2 MHz according to the channel center frequency or the starting frequency. When only the UL Bandwidth field is used without the UL Bandwidth Extension subfield, the value of the UL Bandwidth Extension subfield indicating 160 MHz can indicate any one of 160 MHz, 320 MHz - 1, and 320 MHz - 2 together with the UL Bandwidth Extension subfield. Specifically, the frequency bandwidth indicated by the UL BW subfield, the frequency bandwidth indicated by the UL BW subfield when only the UL BW subfield is used without the UL Bandwidth Extension subfield, the value of the UL Bandwidth Extension subfield, and the frequency bandwidth indicated by the UL BW subfield and the UL Bandwidth Extension subfield together may be as shown in Table 2.

[0359]

Table 2

[0360] In the foregoing embodiments, the frequency bandwidth indicated by the trigger frame can indicate the frequency bandwidth used in the TB PPDU, frame, or transmission sequence transmitted based on the trigger frame.

[0361] The presence and length of the Trigger Dependent User Info subfield included in the Special User Info field may be determined based on the type of the trigger frame. That is, the presence and length of the Trigger Dependent User Info subfield included in the Special User Info field may be determined based on which variant the trigger frame corresponds to. The type of the trigger frame can be indicated by the Trigger Type subfield included in the Common Info field. The value of the Trigger Type subfield may be set to 0 to 7. At this time, the values 0 to 7 of the Trigger Type subfield can indicate a basic trigger frame, a BFRP (Beamforming Report Poll) frame, a MU-BAR frame, a MU-RTS frame, a Buffer Status Report Poll (BSRP) frame, a GCR MU-BAR frame, a BQRP (Bandwidth Query Report Poll) frame, and an NFRP (NDP Feedback Report Poll) frame, respectively.

[0362] In the foregoing embodiments, the HE station that transmits the TB PPDU based on the RA-RU of the trigger frame can also transmit the HE TB PPDU based on the RA-RU even when the trigger frame includes the Special User Info field. Hereinafter, a method for solving this will be described.

[0363] The station can determine the format of the TB PPDU to be transmitted as a response to the trigger frame based on the variant of the User Info field corresponding to the station. Specifically, when the User Info field corresponding to the station in the trigger frame is the HE variant, the station can transmit an HE TB PPDU as a response to the trigger frame. Also, when the User Info field corresponding to the station in the trigger frame is the ETH variant, the station can transmit an EHT TB PPDU as a response to the trigger frame. Further, when the User Info field corresponding to the station in the trigger frame is the NEXT variant, the station can transmit a NEXT TB PPDU as a response to the trigger frame.

[0364] When the HE / EHT P160 subfield indicates the format of the TB PPDU to be transmitted as a response to the trigger frame on the primary 160 MHz channel as an EHT TB PPDU, the User Info field corresponding to the station may be the EHT variant. Also, when the HE / EHT P160 subfield indicates the format of the TB PPDU to be transmitted as a response to the trigger frame on the primary 160 MHz channel as an HE TB PPDU and the RU assigned to the station that received the trigger frame is not included in the primary 160 MHz, the User Info field corresponding to the station may be the EHT variant. Further, when the HE / EHT P160 subfield indicates the format of the TB PPDU to be transmitted as a response to the trigger frame on the primary 160 MHz channel as an HE TB PPDU and the RU assigned to the station that received the trigger frame is included in the primary 160 MHz, the User Info field corresponding to the station may be the HE variant.

[0365] The MU-RTS frame may include the Special User Info field described above. Specifically, a modified MU-RTS frame may include the Special User Info field. The MU-RTS frame can indicate the bandwidth on which the MU-RTS frame is transmitted. Also, as described above, the modified MU-RTS frame can allocate a shared TXOP. The modified MU-RTS frame can indicate the frequency bandwidth used in the shared TXOP. When a frequency bandwidth exceeding 160 MHz is used in the shared TXOP, the modified MU-RTS frame can use the Special User Info field to indicate a frequency bandwidth exceeding 160 MHz. Specifically, according to the embodiment described in FIG. 29, the Special User Info field can indicate a frequency bandwidth exceeding 160 MHz. In such an embodiment, the remaining fields of the Special User Info field excluding the UL Bandwidth Extension field may be set as reserved fields. Specifically, the values of the remaining fields of the Special User Info field excluding the UL Bandwidth Extension field may be set to 0. Also, the UL Bandwidth Extension field of the Special User Info field may be set according to the embodiment described in FIG. 29 above.

[0366] FIG. 30 shows a method of setting TXVECTOR parameters when a station according to an embodiment of the present invention transmits a frame as a response to a modified MU-RTS frame.

[0367] The method for setting the TXVECTOR parameter when the station responds to a modified MU-RTS frame may be different from the method for setting the TXVECTOR parameter when the station responds to a non-modified MU-RTS frame. At this time, the TXVECTOR parameter may include TRIGGER_RESPONDING. TRIGGER_RESPONDING is set to true or false. The TXVECTOR parameter may be a parameter transmitted from the MAC layer to the physical layer. Specifically, when the station performs transmission, the station transmits the TXVECTOR set at the MAC layer to the physical layer. The RXVECTOR parameter may be a parameter transmitted from the physical layer to the MAC layer. Specifically, when the station performs reception, the value of the RXVECTOR parameter is set at the physical layer, and the RXVECTOR parameter is transmitted from the physical layer to the MAC layer.

[0368] TRIGGER_RESPONDING of the TXVECTOR parameter may be set when a non-HT PPDU or a non-HT duplicate PPDU is transmitted. Therefore, among the embodiments of the present invention, the embodiments related to the TRIGGER_RESPONDING setting may be applied when a non-HT PPDU or a non-HT duplicate PPDU is transmitted.

[0369] The station can set TRIGGER_RESPONDING of the TXVECTOR parameter based on whether to transmit a PPDU as a response to the MU-RTS frame. For example, when the station transmits a PPDU as a response to the MU-RTS frame, the station may set TRIGGER_RESPONDING of the TXVECTOR parameter to true. When the station does not transmit a PPDU as a response to the MU-RTS frame, the station can set TRIGGER_RESPONDING of the TXVECTOR parameter to false.

[0370] Also, the transmission conditions of the station may change depending on the value of TRIGGER_RESPONDING in the TXVECTOR parameter. For example, when TRIGGER_RESPONDING in the TXVECTOR parameter is set to true, the station can transmit according to the specified transmission conditions. When TRIGGER_RESPONDING in the TXVECTOR parameter is set to false, the station can transmit regardless of the specified transmission conditions or under transmission conditions that are more relaxed than the specified transmission conditions. Therefore, depending on whether the station transmits a TB PPDU, the transmission conditions that the station should follow may change. Specifically, when the station transmits a TB PPDU, the station can transmit according to the specified conditions. Also, when the station transmits a PPDU that is not a TB PPDU, the station can transmit regardless of the specified conditions or under transmission conditions that are more relaxed than the specified conditions. When the station transmits a non-HT (duplicate) PPDU or a TB PPDU as a response to a MU-RTS frame, multiple stations can transmit PPDUs simultaneously. Therefore, it becomes difficult for the station that receives the PPDU to receive the PPDU due to the transmission parameter settings of multiple stations. Also, the transmission of multiple PPDUs may not be synchronized, and interference may occur between the transmissions of multiple PPDUs. Also, the transmission power difference between multiple PPDUs may increase.

[0371] The pre-specified transmission conditions may include pre-corrected accuracy requirements. Further, the pre-specified transmission conditions may include a pre-corrected transmission time, a pre-corrected transmission frequency and transmission sampling symbol clock, and a pre-corrected transmission power. At this time, the pre-corrected transmission frequency and transmission sampling symbol clock conditions can prevent inter-carrier interference. Further, the pre-corrected transmission power condition can adjust the interference between PPDUs. Further, the pre-specified conditions may include per chain power conditions. Further, the pre-specified transmission conditions may include EVM (error vector magnitude) conditions and spectral mask conditions. Further, the pre-specified conditions may include absolute transmit power accuracy conditions (accuracy of achieving a specified transmit power), RSSI measurement accuracy conditions (the difference between the RSSI and the received power), relative transmit power accuracy conditions (accuracy of achieving a change in transmit power for consecutive PPDUs). Further, the pre-specified conditions may include correcting carrier frequency offset (CFO) errors and symbol clock errors. The carrier frequency offset error correction condition may be that the carrier frequency offset error does not exceed a pre-set level after carrier frequency correction.

[0372] Specifically, when the station transmits the following PPDUs by a triggering PPDU, that is, a PPDU including trigger information, it can correct the carrier frequency offset (CFO) error and the symbol clock error. At this time, the trigger information may include a trigger frame and a TRS Control field. - HE TB PPDU or EHT TB PPDU - Non-HT PPDU or non-HT duplicate PPDU with TRIGGER_RESPONDING of the TXVECTOR parameter set to true

[0373] When measured from 10% of the complementary cumulative distribution function (CCDF) of the AWGN carrier frequency offset error at a received power of -60 dBM at the primary 20 MHz after correction, the absolute value of the remaining carrier frequency offset error corresponding to the triggering PPDU shall not exceed the following levels. - 350 Hz for the data subcarriers of the HE TB PPDU or EHT TB PPDU - 2 kHz for the non-HT PPDU or non-HT duplicate PPDU

[0374] The measurement of the remaining carrier frequency offset error of the EHT TB PPDU should be performed after the HE-SIG-A field or the U-SIG field.

[0375] The measurement of the remaining carrier frequency offset error of the non-HT PPDU or non-HT duplicate PPDU should be performed after the L-STF field. The symbol clock error needs to be compensated up to the ppm amount of only the carrier frequency offset error.

[0376] As a response to a triggering PPDU, a station that transmits an HE TB PPDU, an EHT TB PPDU, a non-HT PPDU, or a non-HT duplicate PPDU must ensure that the transmission start time of the HE TB PPDU, EHT TB PPDU, non-HT PPDU, or non-HT duplicate PPDU at the station's transmit antenna connector is within +-0.4us + 16us from the end of the last OFDM symbol of the triggering PPDU or the end of the PE field of the triggering PPDU.

[0377] However, a response to a modified MU-RTS frame can be transmitted by a single station. Therefore, for the transmission of a response to a modified MU-RTS frame, the above-mentioned pre-specified transmission conditions may not be required, or the pre-specified transmission conditions may be relaxed and applied.

[0378] When transmitting a response to a modified MU-RTS frame and when transmitting a response to a MU-RTS frame that is not a modified MU-RTS frame, a station can set the TRIGGER_RESPONDING of the TXVECTOR parameter differently. Specifically, when a station transmits a response to a modified MU-RTS frame, the station can set the value of TRIGGER_RESPONDING of the TXVECTOR parameter to false. Also, when a station transmits a response to a MU-RTS frame that is not a modified MU-RTS frame, the station can set the value of TRIGGER_RESPONDING of the TXVECTOR parameter to true. Such an embodiment may be applied when a station transmits a non-HT PPDU or a non-HT duplicate PPDU as described above.

[0379] In the embodiment of FIG. 30, the first station (STA1) transmits a MU-RTS frame that is not a modified MU-RTS frame. The second station (STA2) transmits a CTS frame as a response to the MU-RTS frame that is not a modified MU-RTS frame. As in the above-described embodiment, the second station sets the value of TRIGGER_RESPONDING in the TXVECTOR parameter to true and transmits the CTS frame. The first station (STA1) transmits a modified MU-RTS frame. The second station (STA2) transmits a response to the modified MU-RTS frame to the first station (STA1). At this time, the second station sets the value of TRIGGER_RESPONDING in the TXVECTOR parameter to false and transmits a response to the modified MU-RTS frame.

[0380] For convenience of explanation, the modified MU-RTS frame is referred to as a MU-RTS TXOP Sharing (TXS) trigger frame.

[0381] FIG. 31 shows the configuration of a management frame and a MU EDCA Parameter Set element according to an embodiment of the present invention.

[0382] The station can perform channel access based on a plurality of EDCA parameter sets. The channel access may include EDCA (enhanced distributed channel access). The EDCA parameter set may include an EDCA parameter set for each AC (access category). Further, the EDCA parameter sets for each AC included in one EDCA parameter set may have different parameter values from each other. Also, when a plurality of EDCA parameter sets are distinguished into a first EDCA parameter set and a second parameter set, the values of the EDCA parameters of the first EDCA parameter set and the values of the EDCA parameters of the second EDCA parameter set for one AC may be different. Also, the AC may include AC_BE (best effort), AC_BK (background), AC_VI (video), and AC_VO (voice).

[0383] EDCA provides priority for each traffic, specifically CSMA / CA access by AC. Also, multiple EDCA parameter sets may include a legacy EDCA parameter set and a MU EDCA parameter set. Specifically, multiple EDCA parameter sets can be classified into a legacy EDCA parameter set and a MU EDCA parameter set. The legacy EDCA parameter set may be stored in dot11EDCATable, and the MU EDCA parameter set may be stored in dot11MUEDCATable. The EDCA parameter set may include CWmin, CWmax, AIFSN, TXOP limit, and MSDU lifetime. Also, the MU EDCA parameter set may include CWmin, CWmax, AIFSN, and MUEDCATimer. As described above, the EDCA parameter set may include parameter values for each AC. Therefore, the EDCA parameter set may be represented as CWmin[AC], CWmax[AC], AIFSN[AC], TXOP limit[AC], and MSDU lifetime[AC]. Also, the MU EDCA parameter set may be represented as CWmin[AC], CWmax[AC], AIFSN[AC], and MUEDCATimer[AC].

[0384] According to one embodiment, the CW (contention window) may be determined based on CWmin or CWmax. Also, it may be based on CW when invoking a backoff procedure, resetting a backoff counter, or newly selecting. For example, a number randomly selected from integers 0 to CW can be used as the backoff counter. Also, when initializing CW, it may be initialized to CWmin. Also, the minimum value that CW can have may be CWmin. The maximum value that CW can have may be CWmax.

[0385] Based on the AIFSN (arbitration interframe space number), the AIFS described in FIG. 6 may be determined. For example, AIFS may be AIFSN * (slot time (aSlotTime)) + SIFS (aSIFSTime). Specifically, AIFS may be the time to wait when a station performs channel access again after sensing that the channel is busy. Also, AIFS can determine the boundary of the slot used when a station performs channel access again after sensing that the channel is busy.

[0386] The station that has obtained the TXOP (transmit opportunity) can determine the end point of the transmission sequence based on the TXOP limit. Specifically, the station generally ends the transmission sequence within the TXOP limit, and in some exceptional situations, it may be allowed to perform the transmission sequence for a duration exceeding the TXOP limit.

[0387] The station can receive an element indicating the value of the parameters of the EDCA parameter set from the associated AP, and set the EDCA parameter set according to the value of the parameters of the EDCA parameter set indicated by the received element. Also, when the station fails to receive an element indicating the value of the parameters of the EDCA parameter set from the AP associated with the station, the station can set the value of the parameters of the EDCA parameter set to the default value.

[0388] AP can transmit a management frame including an element indicating the value of a parameter of an EDCA parameter set. At this time, the management frame may include a beacon frame, an association response frame, a reassociation response frame, and a probe response frame. Further, the management frame may include a plurality of elements indicating each parameter set of a plurality of EDCA parameter sets. The element indicating the value of the parameter of the legacy EDCA parameter set may be an EDCA Parameter Set. Also, the element indicating the value of the parameter of the MU EDCA parameter set may be an MU EDCA Parameter Set element.

[0389] In FIG. 31, the management frame includes an EDCA Parameter Set element, a Capabilities element, an Operation element, and an MU EDCA Parameter Set element. The Capabilities element and the Operation element may be separately defined for an HT station, a VHT station, an HE station, and an EHT station.

[0390] An element may be identified by an Element ID field or an Element ID Extension field included in the element. The Element ID field and the Element ID Extension field of the EDCA Parameter Set element indicate that it is an EDCA Parameter Set element. Also, the Element ID field and the Element ID Extension field of the MU EDCA Parameter Set element indicate that it is an MU EDCA Parameter Set element.

[0391] The EDCA Parameter Set element and the MU EDCA Parameter Set element may include a parameter record field corresponding to each AC. The EDCA Parameter Set element may include a Parameter Record field for each AC. Further, the MU EDCA Parameter Set element may include a MU Parameter Record field for each AC. The parameter record field may include a sub-field, the ACI field (AC Index), which indicates to which AC each parameter record field corresponds.

[0392] Also, the parameter record field may include a sub-field that indicates CWmin, the ECWmin field, and a sub-field that indicates CWmax, the ECWmax field. At this time, the values of CWmin and CWmax may be as follows. At this time, ECWmin indicates the value of the ECWmin sub-field, and ECWmax indicates the value of the ECWmax sub-field. CWmin = 2^ECWmin - 1 CWmax = 2^ECWmax - 1

[0393] Also, the parameter record field may include a TXOP Limit sub-field or a MU EDCA Timer sub-field. Specifically, the Parameter Record field may include the TXOP Limit sub-field. The TXOP Limit sub-field can indicate the TXOP limit. The MU Parameter Record field may include the MU EDCA Timer sub-field. The MU EDCA Timer sub-field can indicate the MU EDCA timer.

[0394] When a non-AP station successfully transmits triggered by an AP using the first EDCA parameter set, it can perform channel access using the second EDCA parameter set. Performing channel access using an EDCA parameter set may be to update EDCA parameters, such as CWmin, CWmax, AIFSN, and MU EDCA timer, according to the values of the parameters in the EDCA parameter set. At this time, the first EDCA parameter set may be a legacy EDCA parameter set, and the second EDCA parameter set may be a MU EDCA parameter set. At this time, the non-AP station can set a timer that indicates the remaining duration to which the second parameter set is applied when using the second EDCA parameter set. The timer decreases the value of the timer constantly over time, and the non-AP station can use the second EDCA parameter set until the value of the timer becomes 0. When the value of the timer becomes 0, the non-AP station can perform channel access using the first EDCA parameter set. Also, when the non-AP station receives an element indicating a reset of the EDCA parameter set, the non-AP station can set the value of the timer to 0. At this time, the timer may be a MU EDCA timer. In this specification, for convenience of explanation, setting the value of the timer to a non-zero value is described as setting the timer, and the EDCA timer indicating the remaining duration to which the second parameter set is applied is referred to as the timer for the application of the second parameter set. At this time, the non-zero value may be the default value included in the EDCA parameter set.

[0395] Also, the value of the parameter of the first EDCA parameter set may be smaller than the parameter of the second EDCA parameter set. At this time, the success probability of channel access using the second EDCA parameter set may be smaller than the success probability of channel access using the first EDCA parameter set. Thereby, the channel access fairness between stations can be adjusted.

[0396] If a non-AP station successfully transmits a transmission triggered by an AP, it can represent the case where the non-AP station has successfully transmitted a transmission solicited by a basic trigger frame. Also, if the non-AP station has successfully transmitted a transmission solicited by a basic trigger frame, it may be limited to the case where the non-AP station has successfully transmitted a QoS data frame solicited by a basic trigger frame. When the non-AP station successfully transmits a QoS data frame, it may be defined as follows. When the QoS data frame requests an immediate response, the non-AP station may be considered to have successfully transmitted the QoS data frame when the non-AP station receives an immediate response to the QoS data frame. Also, when the QoS data frame does not request an immediate response, the non-AP station may be considered to have successfully transmitted the QoS data frame when the non-AP station transmits the QoS data frame. Therefore, when the non-AP station transmits a QoS data frame that requests an immediate response and receives an immediate response to the QoS data frame, the non-AP station can update the EDCA parameters with the second EDCA parameter set. Also, when the non-AP station transmits a QoS data frame that does not request an immediate response, the non-AP station can update the EDCA parameters with the second EDCA parameter set. At this time, the non-AP station can update the EDCA parameters corresponding to the AC of the QoS data frame with the second EDCA parameter set. Also, when the non-AP station transmits a QoS data frame that requests an immediate response and receives an immediate response to the QoS data frame, the non-AP station can set a timer for the application of the second EDCA parameter set. At this time, the EDCA timer may be started at the end of the PPDU including the immediate response.Also, when a non-AP station transmits a QoS data frame that does not request an immediate response, the non-AP station can set a timer for the application of the second EDCA parameter set. At this time, the timer for the application of the second EDCA parameter set may be started at the end of the PPDU including the QoS data frame.

[0397] FIG. 32 shows a method for a station to which a shared TXOP according to an embodiment of the present invention is assigned to set MU EDCA parameter sets.

[0398] The first EDCA parameter set and the second EDCA parameter set in the embodiment described with reference to FIG. 32 may be the same as the first EDCA parameter set and the second EDCA parameter set in the embodiment described with reference to FIG. 31.

[0399] A station to which TXOP sharing is assigned can perform channel access using the second EDCA parameter set described above. At this time, the second EDCA parameter set may be the MU EDCA parameter set described above. In still other specific embodiments, the second EDCA parameter set may be an EDCA parameter set with a lower priority than the legacy EDCA parameter set described above. By such an embodiment, the channel access fairness between a station to which a shared TXOP is assigned and a station to which a shared TXOP is not assigned can be adjusted. For convenience of explanation, a station to which a shared TXOP is assigned is referred to as a shared TXOP assignee, and a shared TXOP holder is referred to as a shared TXOP holder.

[0400] When the station that has received the MU-RTS TXS trigger frame transmits a response to the MU-RTS TXS trigger frame, the station can switch the EDCA parameters used for channel access from the first EDCA parameter set to the second EDCA parameter set. The response frame to the MU-RTS TXS trigger frame may be a CTS frame. Therefore, the response to the MU-RTS TXS trigger frame can indicate a CTS frame or a PPDU including the CTS frame. When the station that has received the MU-RTS TXS trigger frame transmits a response to the MU-RTS TXS trigger frame, the station can perform channel access using the second EDCA parameter set within the shared TXOP. Such an embodiment may be applicable only when the MU-RTS TXS trigger frame allows transmission only to one of the stations that are shared TXOP holders, for example, an AP. That is, such an embodiment may not be applicable when the MU-RTS TXS trigger frame allows transmission by a plurality of stations that are shared TXOP holders, for example, an AP and other non-AP stations.

[0401] In yet another specific embodiment, when the station to which the shared TXOP is allocated transmits at least one frame to the shared TXOP allocator, the station can switch the EDCA parameters used for channel access from the first EDCA parameter set to the second EDCA parameter set.

[0402] In addition, a station to which a shared TXOP is assigned can set a timer for applying the second EDCA parameter set at the end of the shared TXOP. In still other specific embodiments, a station to which a shared TXOP is assigned can set a timer for applying the second EDCA parameter set when it receives a response corresponding to the signaling for ending the shared TXOP. In still other specific embodiments, a station to which a shared TXOP is assigned can set a timer for applying the second EDCA parameter set at the earlier of the end of the shared TXOP or when it receives a response corresponding to the signaling for ending the shared TXOP. At this time, setting the timer for applying the second EDCA parameter set may be, as described above, setting the value of the timer for applying the second EDCA parameter set to a value greater than 0.

[0403] In the embodiment of FIG. 32, a first station (STA1) transmits a MU-RTS TXS trigger frame to a second station (STA2) to assign a shared TXOP to the second station (STA2). At this time, the second station (STA2) transmits a CTS frame to the first station (STA1). As described above, when the second station (STA2) transmits a CTS frame to the first station (STA1), the second station (STA2) switches the first EDCA parameter set to the second EDCA parameter set and performs channel access using the second EDCA parameter set. In addition, the second station (STA2) can set a timer for applying the second EDCA parameter at the end of the shared TXOP. This is to prevent the value of the timer from continuously decreasing even though the shared TXOP holder does not perform channel access when setting the timer for applying the second EDCA parameter when switching to the second EDCA parameter set. Thereby, fairness with other stations can be guaranteed.

[0404] In FIG. 32 and the like, after a shared TXOP holder transmits a frame within a shared TXOP, an example is described in which the shared TXOP holder switches the EDCA parameters used for channel access from a first parameter set, for example, a legacy EDCA parameter set, to a second parameter set, for example, a MU EDCA parameter set. Such an example may be applied only when the shared TXOP holder successfully transmits a frame. Therefore, when the shared TXOP holder successfully transmits a frame, the shared TXOP holder can switch the EDCA parameters used for channel access from the first parameter set to the second parameter set. Also, such an example may be applied only when the shared TXOP holder successfully transmits a QoS data frame. Also, when the shared TXOP holder successfully transmits a QoS data frame, the shared TXOP holder can switch the EDCA parameters used for channel access from the first parameter set to the second parameter set. When the QoS data frame requires an immediate response, successfully transmitting the QoS data frame may be transmitting the QoS data frame and receiving an ACK for the transmitted QoS data frame. Also, when the QoS data frame does not require an immediate response, successfully transmitting the QoS data frame may be transmitting the QoS data frame. When the shared TXOP holder successfully transmits a QoS data frame to the shared TXOP assignee within the shared TXOP, the value of an EDCA timer for applying the second parameter set, for example, the value of a MU EDCA timer, is set to a non-zero value.

[0405] Therefore, when a QoS data frame requests an immediate response, the shared TXOP holder can send the QoS data frame to the shared TXOP allocator within the shared TXOP and set an EDCA timer for the application of the second parameter set at the end of the PPDU including the immediate response to the QoS data frame received from the shared TXOP allocator. When the QoS data frame does not request an immediate response, an EDCA timer for the application of the second parameter set can be set at the end of the PPDU including the QoS data frame transmitted to the shared TXOP allocator within the shared TXOP.

[0406] In the foregoing embodiments, it has been described that the embodiment in which the shared TXOP holder switches the EDCA parameters used for channel access from the first EDCA parameter set to the second EDCA parameter set after transmitting a frame within the shared TXOP is applicable only in the first shared TXOP mode. This is because it may become difficult for the shared TXOP allocator to monitor the frame exchange between the shared TXOP holder and other stations. Also, when the shared TXOP holder does not perform a frame exchange with the shared TXOP allocator, it is difficult to say that the shared TXOP holder has obtained an advantage compared to other stations in the frame exchange with the shared TXOP allocator.

[0407] FIG. 33 shows the operation of a station according to an embodiment of the present invention to recover a TXOP after allocating a shared TXOP.

[0408] Within a co-TXOP, the co-TXOP assignee can transmit only when the pre-specified conditions are met. The pre-specified conditions may include at least one of the co-TXOP assignee transmitting an immediate response to the transmission of the co-TXOP holder within the co-TXOP and performing a TXOP recovery operation. At this time, the TXOP recovery operation may be performed when no frames are exchanged within the co-TXOP. When no transmission or reception has occurred for a certain period of time or more within the co-TXOP, the station can determine that no frames are being exchanged. Also, when a transmission failure occurs within the co-TXOP, the station can determine that no frames are being exchanged. At this time, when no immediate response to the transmitted frame is made, the station can determine that the transmission has failed.

[0409] Also, when the station receives a frame for which it does not request an immediate response, the station can determine that no frames are being exchanged. Specifically, when the station receives an A-MPDU that contains only MPDUs for which it does not request an immediate response, the station can determine that no frames are being exchanged. When the station cannot successfully receive all MPDUs of the A-MPDU, the station cannot determine whether the A-MPDU contains only MPDUs for which it does not request an immediate response. Therefore, when the station cannot successfully receive all MPDUs of the A-MPDU, the station cannot perform TXOP recovery.

[0410] As described above, when transmission or reception is not performed for a certain period of time or longer within a shared TXOP, the station can determine that frames are not being exchanged. Specifically, when the channel on which TXOP sharing has been performed for a certain period of time or longer within a shared TXOP is idle, the station can determine that frames are not being exchanged. At this time, the certain period of time may be PIFS. Also, the fact that the channel is idle may mean that the CS (carrier sense) result of the channel is idle. At this time, CS may be ED (energy detection). When the station senses the energy of a signal that is equal to or greater than the ED threshold in ED, the station can determine that the medium is busy. Also, when the station senses the energy of a signal that is less than the ED threshold in ED, the station can determine that the medium is idle.

[0411] In this specification, the fact that the channel is idle at the TxPIFS slot boundary may be regarded as the CS result being idle at PIFS, or the channel being idle at PIFS. Also, in this specification, starting transmission at a specific time, particularly after PIFS from the end of the PPDU, may be described on the premise that the channel is idle at PIFS. Also, in this specification, not being able to start transmission at a specific time, particularly after PIFS from the end of the PPDU, may be described on the premise that the channel is busy at PIFS.

[0412] Also, PIFS may be the time obtained by adding SIFS (aSIFSTime) and slot time (aSlotTime). Also, the TxPIFS slot boundary may be the time aRxTxTurnaroundTime before the time that is PIFS later than the time when the channel switches to the idle state. Therefore, the TxPIFS slot boundary may be TxSIFS slot boundary + aSlotIme. TxSIFS may be the time aRxTxTurnaroundTime before the time that is SIFS later than the time when the channel switches to the idle state. aRxTxTurnaroundTime may be a value determined based on the time it takes for the station to switch from the reception state to the transmission state. Specifically, aRxTxTurnaroundTime may be the time it takes for the station to switch from the reception state to the transmission state. In yet another specific embodiment, aRxTxTurnaroundTime may be the maximum time it takes for the station to switch from the reception state to the transmission state. SIFS may be 16 us, slot time may be 9 us, and PIFS may be 25 us. Specifically, when frame exchange is performed in the 5 GHz band or 6 GHz band, SIFS may be 16 us, slot time may be 9 us, and PIFS may be 25 us. Also, SIFS may be 10 us, slot time may be 9 us, and PIFS may be 19 us. Specifically, when frame exchange is performed in the 2.4 GHz band, SIFS may be 10 us, slot time may be 9 us, and PIFS may be 19 us.

[0413] Also, the embodiment for performing the above-described TXOP recovery may be applicable only in the first shared TXOP mode. Specifically, it may be applicable only when the shared TXOP holder is not allowed to transmit a P2P frame within the shared TXOP.

[0414] Further, the aforementioned TXOP recovery may be applicable only when the shared TXOP holder receives or transmits the last frame before PIFS from the end point of the shared TXOP. At this time, when the shared TXOP holder receives or transmits the last frame after a time point just earlier than PIFS from the end point of the shared TXOP, the station can perform channel access after the shared TXOP.

[0415] Also, in the above-described embodiments, the TXOP recovery has been described as being performed by the shared TXOP allocator, but the shared TXOP holder can perform TXOP recovery according to the above-described embodiments.

[0416] In the embodiment of FIG. 33, the first station (STA1) transmits a MU-RTS TXS trigger frame to the second station (STA2) to allocate a shared TXOP to the second station (STA2). At this time, the second station (STA2) transmits a CTS frame to the first station (STA1). Within the shared TXOP, the first station (STA1) transmits a frame (DL frame 1) to the second station (STA2) and determines that the channel is idle at PIFS. When the first station (STA1) determines that the channel is idle at PIFS, the first station (STA1) transmits a frame (DL frame 2) as a TXOP recovery operation.

[0417] In FIG. 33, a method of recovering TXOP within a shared TXOP has been described. When the shared TXOP ends, the TXOP obtained by the shared TXOP allocator may not end. At this time, a method for the shared TXOP allocator to recover the TXOP may be required. This will be described with reference to FIG. 34.

[0418] FIG. 34 shows that a shared TXOP allocator performs TXOP recovery after the end of the shared TXOP according to an embodiment of the present invention.

[0419] First, within a shared TXOP, the shared TXOP assignee can transmit according to the following conditions.

[0420] When the shared TXOP assignee that has transmitted a MU-RTS TXS trigger frame in the first shared TXOP mode receives a CTS frame from the shared TXOP holder, the shared TXOP assignee can start transmission within the shared TXOP only in the following cases.

[0421] When the shared TXOP assignee receives a PPDU requesting an immediate response from the shared TXOP holder within the shared TXOP, the shared TXOP assignee can start transmission within the shared TXOP. Also, when the channel is idle at the TxPIFS slot boundary from the end of the last immediate response transmission sent to the station in the first shared TXOP mode or the end of the frame transmission that does not request an immediate response received from the TXOP holder, the shared TXOP assignee can start transmission within the shared TXOP.

[0422] When the shared TXOP assignee that has transmitted a MU-RTS TXS trigger frame in the second shared TXOP mode receives a CTS frame from the shared TXOP holder, the shared TXOP assignee can start transmission within the shared TXOP only in the following cases.

[0423] When the shared TXOP assignee receives a PPDU requesting an immediate response from the shared TXOP holder within the shared TXOP, the shared TXOP assignee can start transmission within the shared TXOP.

[0424] Also, when the TXNAV timer expires, that is, when the TXOP acquired by the shared TXOP assignee expires, the shared TXOP assignee cannot transmit any PPDU without performing a new backoff procedure.

[0425] After the shared TXOP ends, if the shared TXOP does not end, the shared TXOP assignee can start transmission when any one of the pre-specified conditions is met.

[0426] Condition 1: The co-TXOP assignee can perform CS at the end of the co-TXOP and can determine that the channel is idle at PIFS. At this time, the co-TXOP assignee can transmit a PPDU at a time that is only PIFS later than the end of the co-TXOP.

[0427] Condition 2: The transmission of the PPDU by the co-TXOP assignee may end after a time that is only SIFS earlier than the end of the co-TXOP. At this time, the co-TXOP assignee can transmit a PPDU at a time that is only SIFS later than the end of the PPDU transmitted by the co-TXOP assignee. Specifically, the co-TXOP assignee can transmit a PPDU after SIFS from the end of the PPDU transmitted by the co-TXOP assignee without performing CS.

[0428] Condition 3: The co-TXOP assignee performs CS at the end of the co-TXOP and can determine that the channel is not idle. At this time, the co-TXOP assignee can transmit a PPDU when the channel is idle, that is, when the channel is idle at the TxPIFS slot boundary.

[0429] Condition 4: The co-TXOP assignee can perform a backoff procedure to obtain a TXOP and obtain the TXOP. At this time, the co-TXOP assignee can transmit a PPDU.

[0430] In the embodiment of FIG. 34, the first station (STA1) transmits a MU-RTS TXS trigger frame to the second station (STA2) to allocate a co-TXOP (shared TXOP) to the second station (STA2). At this time, the second station (STA2) transmits a CTS frame to the first station (STA1).

[0431] In the embodiment of FIG. 34(a), when the first station (STA1) transmits the first frame (DL frame 1) within the shared TXOP, there remains a time that is smaller than PIFS and larger than SIFS until the end of the shared TXOP. At this time, the first station (STA1) performs CS at the end of the shared TXOP and determines that the channel is idle at PIFS. Therefore, the first station (STA1) can transmit the second frame (DL frame 2) at a time that is PIFS later than the end of the shared TXOP. However, the interval between the first frame (DL frame 1) and the second frame (DL frame 2) is larger than 25 us. Therefore, this may correspond to a violation of the existing regulations. Specifically, this may violate the regulation that when a station that has acquired TXOP in the wireless LAN standard performs frame exchange, the interval between frames is not allowed to be larger than 25 us.

[0432] In the embodiment of FIG. 34(b), when the second station (STA1) transmits a frame (UL frame or P2P frame) within the shared TXOP, there remains a time that is smaller than PIFS and larger than SIFS until the end of the shared TXOP. At this time, the first station (STA1) performs CS at the end of the shared TXOP and determines that the channel is idle at PIFS. Therefore, the first station (STA1) can transmit a frame (DL frame) at a time that is PIFS later than the end of the shared TXOP. At this time, the interval between the PPDUs transmitted by the first station (STA1) is larger than 25 us. Also, the interval between the PPDU transmitted by the second station (STA2) and the PPDU transmitted by the first station (STA1) is larger than 25 us. Therefore, this may also violate the regulation regarding the transmission interval within the aforementioned TXOP.

[0433] Also, when the first station (STA1) cannot sense all frame exchanges within the shared TXOP and performs CS at the end of the shared TXOP or when frame exchange ends at the end of the shared TXOP, the interval between PPDUs is greater than 25 us. This is the same even when PPDU transmission is performed according to condition 3 described above. That is, the interval between the PPDU transmitted last within the shared TXOP and the PPDU that the first station (STA1) transmits for the first time after the shared TXOP is greater than 25 us. This may also violate the regulation regarding the transmission interval within the TXOP described above.

[0434] In the embodiment of FIG. 34(c), the transmission of the first frame (DL frame 1) of the first station (STA1) ends at a time point just SIFS earlier than the end of the shared TXOP. At this time, the first station (STA1) can transmit the second frame (DL frame 2) after SIFS from the end of the PPDU including the first frame (DL frame 1).

[0435] TXOP recovery after the end of the shared TXOP that does not violate the regulation regarding the interval between PPDUs transmitted within the TXOP will be described with reference to FIG. 35.

[0436] FIG. 35 is a diagram showing that the shared TXOP allocator performs TXOP recovery after the end of the shared TXOP according to still another embodiment of the present invention.

[0437] The first condition described with reference to FIG. 34 may be modified as follows. The end of the last PPDU of the shared TXOP may be after a point in time that is PIFS earlier than the end of the shared TXOP. At this time, when the channel is idle between the end of the last PPDU transmitted within the shared TXOP and PIFS, the shared TXOP allocator can transmit a PPDU at a point in time that is PIFS later than the end of the last PPDU transmitted within the shared TXOP. Such an embodiment may be applicable only when the shared TXOP holder is not permitted to transmit to stations other than the shared TXOP allocator within the shared TXOP. In this specification, the PPDUs transmitted within the shared TXOP can refer only to the PPDUs transmitted by the shared TXOP holder within the shared TXOP and the PPDUs transmitted in response to the PPDUs transmitted by the shared TXOP holder. For convenience of explanation, the last PPDU transmitted within the shared TXOP is referred to as the last PPDU of the shared TXOP. Also, the case where the shared TXOP holder is not permitted to transmit to stations other than the shared TXOP allocator within the shared TXOP is referred to as the first TXOP sharing mode. Also, the case where the shared TXOP holder is permitted to transmit to stations other than the shared TXOP allocator within the shared TXOP is referred to as the second TXOP sharing mode.

[0438] At this time, the last PPDU of the shared TXOP may be a PPDU transmitted by the shared TXOP holder. At this time, the shared TXOP allocator can perform TXOP recovery according to the above-described embodiment only when the PPDU does not include a frame that requests an immediate response.

[0439] In the embodiment of FIG. 35, the first station (STA1) transmits a MU-RTS TXS trigger frame to the second station (STA2) to allocate a shared TXOP to the second station (STA2). At this time, the second station (STA2) transmits a CTS frame to the first station (STA1).

[0440] In the embodiment of FIG. 35(a), when the first station (STA1) transmits the first frame (DL frame 1) within the shared TXOP, there remains a time smaller than PIFS and larger than SIFS until the end of the shared TXOP. At this time, the first station (STA1) performs CS at the end of the first frame (DL frame 1) and determines that the channel is idle at PIFS. Therefore, the first station (STA1) can transmit the second frame (DL frame 2) at a time PIFS later than the end of the first frame (DL frame 1). Therefore, the interval between the first frame (DL frame 1) and the second frame (DL frame 2) is smaller than 25 us.

[0441] In the embodiment of FIG. 35(b), when the second station (STA1) transmits a frame (UL frame) within the shared TXOP, there remains a time smaller than PIFS and larger than SIFS until the end of the shared TXOP. At this time, the first station (STA1) performs CS at the end of the PPDU including the frame (UL frame) and determines that the channel is idle at PIFS. Therefore, the first station (STA1) can transmit a frame (DL frame) at a time PIFS later than the end of the PPDU including the frame (UL frame). At this time, the interval between the PPDU transmitted by the second station (STA2) and the PPDU transmitted by the first station (STA1) is smaller than 25 us.

[0442] In yet another specific embodiment, when the duration of the remaining shared TXOP is smaller than the PIFS, the shared TXOP holder may not be allowed to start transmission. When the duration of the remaining shared TXOP is smaller than the PIFS, the shared TXOP allocator can transmit a PPDU at a time that is only SIFS later than the end of the PPDU transmitted as the last PPDU of the shared TXOP. At this time, the shared TXOP allocator can transmit a PPDU at a time that is only SIFS later than the end of the PPDU transmitted as the last PPDU of the shared TXOP without performing a CS. This is because, since the duration of the remaining shared TXOP is smaller than the PIFS, it can be ensured that the shared TXOP holder does not perform transmission. In such an embodiment, when the last PPDU of the shared TXOP is a PPDU transmitted by the shared TXOP allocator and the duration of the remaining shared TXOP is smaller than the SIFS, the station that has received the allocation can transmit a PPDU according to the second condition described in FIG. 34.

[0443] When the duration of the remaining shared TXOP is smaller than the PIFS, the shared TXOP holder and the station that has been allocated the TXOP may not be allowed to start transmission. Specifically, when the duration of the remaining shared TXOP is smaller than the PIFS and larger than the SIFS, the shared TXOP holder and the station that has been allocated the TXOP may not be allowed to start transmission.

[0444] Also, after the shared TXOP has ended, the following condition may be added as a condition for the shared TXOP allocator to start transmission if the shared TXOP has not ended.

[0445] Condition 5: The co-TXOP assignee can receive a frame requesting an immediate response from the co-TXOP holder. At this time, the co-TXOP assignee can transmit the PPDU at a time that is SIFS later than the end of the PPDU including the frame requesting the immediate response. At this time, the interval between the end of the PPDU including the frame requesting the immediate response and the end of the co-TXOP for the station that has received the TXOP assignment may be equal to or less than a specified value. The specified value may be SIFS. The specified value may be 0.

[0446] As described above, the embodiment described with reference to FIG. 35 may be applied in the first co-TXOP mode. The TXOP recovery after the end of the co-TXOP in the second co-TXOP mode will be described with reference to FIG. 36.

[0447] FIG. 36 is a diagram showing that the co-TXOP assignee performs TXOP recovery after the end of the co-TXOP according to still another embodiment of the present invention.

[0448] The embodiment described with reference to FIG. 35 may also be applied in the second co-TXOP mode. However, the embodiment described with reference to FIG. 35 may be applied in the second co-TXOP mode only when the last PPDU of the co-TXOP contains a frame whose intended recipient is the co-TXOP assignee.

[0449] Therefore, in the second co-TXOP mode, the last PPDU of the co-TXOP may contain a frame whose intended recipient is the co-TXOP assignee, and the end of the last PPDU of the co-TXOP may be after a time that is PIFS earlier than the end of the co-TXOP. At this time, when the channel is idle between the end of the last PPDU of the co-TXOP and PIFS, the co-TXOP assignee can transmit the PPDU at a time that is PIFS later than the end of the last PPDU of the co-TXOP. Such an embodiment may be applied only when the last PPDU of the co-TXOP does not contain a frame requesting an immediate response.

[0450] Also, when the duration of the remaining shared TXOP is smaller than PIFS, the shared TXOP holder may not be permitted to start transmission. When the duration of the remaining shared TXOP is smaller than PIFS, the shared TXOP assignee can transmit a PPDU at a time that is only SIFS later than the end of the last PPDU of the shared TXOP. At this time, the shared TXOP assignee can transmit a PPDU at a time that is only SIFS later than the end of the last PPDU of the shared TXOP without performing CS.

[0451] In still other specific embodiments, when the duration of the remaining shared TXOP is smaller than PIFS, the shared TXOP holder and the station that allocated the TXOP may not be permitted to start transmission. Specifically, when the duration of the remaining shared TXOP is smaller than PIFS and larger than SIFS, the shared TXOP holder and the station that allocated the TXOP may not be permitted to start transmission.

[0452] However, different from the embodiment of FIG. 36, the shared TXOP assignee needs to determine whether the last PPDU of the shared TXOP contains a frame that is intended for the shared TXOP assignee. Specifically, the shared TXOP assignee can determine whether the frame included in the last PPDU of the shared TXOP is a frame that the shared TXOP holder transmits to the shared TXOP assignee.

[0453] In the embodiment of FIG. 36, the first station (STA1) transmits an MU-RTS TXS trigger frame to the second station (STA2) to allocate a shared TXOP to the second station (STA2). At this time, the second station (STA2) transmits a CTS frame to the first station (STA1). In the embodiment of FIG. 36(a), when the second station (STA2) transmits a UL frame within the shared TXOP, there remains a time smaller than PIFS and larger than SIFS until the end of the shared TXOP. At this time, the first station (STA1) performs CS at the end of the UL frame and determines that the channel is idle at PIFS. Therefore, the first station (STA1) can transmit a DL frame at a time point delayed by PIFS from the end of the UL frame. Therefore, the interval between the UL frame and the DL frame 2 is smaller than 25 us.

[0454] When the intended recipient of the frame included in the last PPDU of the shared TXOP is the shared TXOP holder, the shared TXOP allocator may be permitted to perform TXOP recovery according to the embodiment of FIG. 36(a).

[0455] When the transmitter of the frame included in the last PPDU of the shared TXOP is the station that received the TXOP allocation, and the intended receiver is a station other than the shared TXOP allocator, the shared TXOP allocator can perform TXOP recovery based on whether the last PPDU of the shared TXOP includes a frame that requests an immediate response. When the transmitter of the frame included in the last PPDU of the shared TXOP is the station that received the TXOP allocation, the intended receiver is a station other than the shared TXOP allocator, and the last PPDU of the shared TXOP includes a frame that requests an immediate response, it is not necessary for the shared TXOP allocator to perform TXOP recovery by the embodiment described in FIG. 36(a). This is because the shared TXOP allocator may have difficulty receiving the response frame transmitted by the P2P peer station within the shared TXOP. When the channel is idle between the PPDU including the immediate response to the frame that requests the immediate response described above and the PIFS, the station that allocated the TXOP can start transmission at a time point that is only PIFS later than the PPDU including the immediate response. In still other specific embodiments, the station that allocated the TXOP can start transmission at a time point that is only SIFS later than the PPDU including the immediate response.

[0456] In FIG. 36(b), when the second station (STA2) transmits a P2P frame within the shared TXOP, there remains a time that is smaller than the PIFS and larger than the SIFS until the end of the shared TXOP. At this time, the P2P frame does not request an immediate response. The first station (STA1) performs a CS at the end of the P2P frame and determines that the channel is idle at the PIFS. Therefore, the first station (STA1) can transmit a DL frame at a time point that is only PIFS later than the end of the P2P frame. Therefore, the interval between the P2P frame and the DL frame 2 is smaller than 25 us.

[0457] In FIG. 36(C), when a P2P frame is transmitted to a second station (STA2) within a shared TXOP, there remains a time smaller than PIFS and larger than SIFS until the end of the shared TXOP. A first station (STA1) performs CS at the end of the P2P frame and determines that the channel is idle at PIFS. Therefore, the first station (STA1) can transmit a DL frame at a time delayed by only PIFS from the end of the UL frame. Therefore, the interval between the UL frame and the DL frame 2 is smaller than 25 us.

[0458] In the foregoing embodiments, the station to which the TXOP is allocated can determine the intended recipient of the received frame based on the recipient address of the received frame, for example, the RA field. Specifically, the station to which the TXOP is allocated can determine the station indicated by the recipient address of the received station as the intended recipient. Also, the station to which the TXOP is allocated can determine the sender of the received frame based on the sender address of the received frame, for example, the TA field. Specifically, the station to which the TXOP is allocated can determine the station indicated by the sender address of the received station as the sender. Also, the station to which the TXOP is allocated can determine the intended recipient of the frame included in the received PPDU based on the STA-ID field in the signaling field of the received PPDU. Also, the station to which the TXOP is allocated can determine the intended recipient of the frame included in the received PPDU based on the STA-ID field and the BSS color field in the signaling field of the received PPDU. Also, the station to which the TXOP is allocated can determine the intended recipient of the frame included in the received PPDU based on the STA-ID field, the BSS color field, and the UL / DL field in the signaling field of the received PPDU. At this time, the STA-ID field indicates the ID of the station that is the intended recipient of the frame included in the PPDU. Also, the BSS color field indicates the BSS color of the BSS to which the PPDU is transmitted. Also, the UL / DL field indicates whether the PPDU is an uplink transmission PPDU or a downlink transmission PPDU.

[0459] When the channel is busy at the end of the shared TXOP, even within the TXOP acquired by the shared TXOP assignee that includes the shared TXOP, it may not be allowed for the shared TXOP assignee to start frame exchange without performing the backoff procedure for acquiring the TXOP. A situation may occur where a station allowed to transmit within the shared TXOP is unable to transmit. At this time, even if the shared TXOP assignee starts transmitting immediately after the shared TXOP ends, the interval between the PPDU transmitted by the shared TXOP assignee and the PPDU transmitted within the shared TXOP may be greater than 25 us. Therefore, the shared TXOP assignee can perform the backoff procedure for acquiring the TXOP again.

[0460] Also, it may be the case that the frame included in the last PPDU of the shared TXOP cannot be successfully received, or the frame included in the last PPDU of the shared TXOP is not included in the frame exchange of the shared TXOP holder. At this time, even within the TXOP acquired by the shared TXOP assignee that includes the shared TXOP, it may not be allowed for the shared TXOP assignee to start frame exchange without performing the backoff procedure for acquiring the TXOP. When the frame included in the last PPDU of the shared TXOP is not included in the frame exchange of the shared TXOP holder, it means that the receiver of the frame included in the last PPDU of the shared TXOP is not the shared TXOP holder and the transmitter of the frame included in the last PPDU of the shared TXOP is not the shared TXOP holder. This is because it is not guaranteed that the interval between the PPDU transmitted by the s...

Claims

1. A station in a wireless communication system, including a transceiver, and a processor for controlling the transceiver, wherein the processor is configured to: receive a trigger frame from an AP (Access Point), the trigger frame allocating a part of a transmission opportunity (TXOP) obtained by the AP to the station as a shared TXOP; transmit a CTS frame as a response to the trigger frame; transmit a non-TB (Trigger Based) PPDU (physical layer protocol data unit) within the shared TXOP; switch a first EDCA (enhanced distributed channel access) parameter set used for channel access to a second EDCA parameter set based on transmission of a QoS (quality of service) data frame included in the non-TB PPDU; perform the channel access according to the second EDCA parameter set; and is configured to perform the above operations. A station.

2. The station according to claim 1, wherein the processor is configured to switch the first EDCA parameter set to the second EDCA parameter set when the QoS data frame is successfully transmitted to the AP within the shared TXOP.

3. The station according to claim 2, wherein the processor is configured to switch the first EDCA parameter set to the second EDCA parameter set when the station transmits a QoS data frame requesting an immediate response to the AP via the non-TB PPDU and receives a response to the QoS data frame requesting the immediate response within the shared TXOP.

4. The station according to claim 2, wherein the processor is configured to switch the first EDCA parameter set to the second EDCA parameter set when the station transmits the non-TB PPDU including a QoS data frame that does not request an immediate response to the AP within the shared TXOP.

5. The value of the timer for the remaining duration applied to the second EDCA parameter set is set to a value greater than 0 when the QoS data frame is successfully transmitted to the AP. The station according to claim 2.

6. The processor is configured not to set the value of the timer to 0 even if the station successfully transmits signaling to deactivate the UL MU transmission operation within the shared TXOP to the AP. The station according to claim 5.

7. The processor is configured to set the value of the timer to 0 when the station successfully transmits signaling to deactivate the shared TXOP operation to the AP. The station according to claim 5.

8. Based on whether UL MU (multiuser) transmission is successfully executed, the second EDCA parameter set is used instead of the first EDCA parameter set. The station according to claim 1.

9. When the remaining duration of the shared TXOP is shorter than the Point Coordination Function (PCF) Interframe Space (PIFS), the transmission of the AP is not permitted except for one or more predetermined transmissions. The one or more predetermined transmissions are executed by the AP after a Short Interframe Space (SIFS) from the end of the transmission of the last PPDU transmitted from the station within the shared TXOP, and the last PPDU does not require an immediate response. The station according to claim 1.

10. A method of operating a station in a wireless communication system, comprising: Receiving a trigger frame for triggering an uplink transmission from an AP (Access Point), wherein the trigger frame allocates a part of a transmission opportunity (TXOP) obtained by the AP as a shared TXOP to the station; Transmitting a CTS frame as a response to the trigger frame; Transmitting a non-TB (Trigger Based) PPDU (physical layer protocol data unit) within the shared TXOP; Based on the transmission of the QoS (quality of service) data frame included in the non-TB PPDU, switching the first EDCA (enhanced distributed channel access) parameter set used for channel access to the second EDCA parameter set; Executing the channel access according to the second EDCA parameter set; A method comprising:

11. The step of switching the first EDCA parameter set used for channel access to the second EDCA parameter set includes switching the first EDCA parameter set to the second EDCA parameter set when the station successfully transmits the QoS data frame to the AP within the shared TXOP. The method according to claim 10.

12. The step of switching the first EDCA parameter set to the second EDCA parameter set when the station successfully transmits the QoS data frame to the AP within the shared TXOP includes the station transmitting a QoS data frame requesting an immediate response to the AP via the non-TB PPDU and receiving a response to the QoS data frame requesting the immediate response within the shared TXOP. The method according to claim 11, further comprising switching the first EDCA parameter set to the second EDCA parameter set.

13. The step of switching the first EDCA parameter set to the second EDCA parameter set when the station successfully transmits the QoS data frame to the AP within the shared TXOP includes the station transmitting the non-TB PPDU including the QoS data frame not requesting an immediate response to the AP within the shared TXOP. The method according to claim 11, further comprising switching the first EDCA parameter set to the second EDCA parameter set.

14. The step of switching the first EDCA parameter set to the second EDCA parameter set includes setting a value of a timer for a remaining duration applied to the second EDCA parameter set to a value greater than 0 when the QoS data frame is successfully transmitted to the AP. The method according to claim 11.

15. The method according to claim 14, further comprising a stage where, even if the station successfully transmits signaling for deactivating the UL MU transmission operation to the AP within the shared TXOP, the value of the timer is not set to 0.

16. The method according to claim 14, further comprising a stage where, when the station successfully transmits signaling for deactivating the shared TXOP operation to the AP, the value of the timer is set to 0.

17. The method according to claim 10, wherein the second EDCA parameter set is used instead of the first EDCA parameter set based on whether UL MU (multiuser) transmission is successfully executed.

18. When the remaining duration of the shared TXOP is shorter than the point coordination function (PCF) interframe space (PIFS), the transmission of the AP is not permitted except for one or more predetermined transmissions, and the one or more predetermined transmissions are executed by the AP after a short interframe space (SIFS) from the end of the transmission of the last PPDU transmitted from the station within the shared TXOP, and the last PPDU does not require an immediate response. The method according to claim 10.

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