Wireless communication method and wireless communication terminal using the same

Abstract

Disclose a wireless communication method and a wireless communication terminal using the method. The wireless communication terminal includes: a transmitting / receiving unit and a processor. Using the transmitting / receiving unit, the processor receives a downlink multi-user (DL MU) PPDU including information for uplink multi-user (UL MU) transmission from a basic wireless communication terminal, and transmits a UL MU PPDU to the basic wireless communication terminal based on the information for UL MU transmission.

Description

[0001] This application is a divisional application of the patent application with the application number 201780022881.9 (PCT / KR2017 / 003932), the international filing date of which is April 11, 2017, and the Chinese filing date of which is October 10, 2018, and the invention title of which is "Wireless communication method supporting multi-user cascaded transmission and wireless communication terminal using the same". Technical Field

[0002] The present invention relates to a wireless communication method and a wireless communication terminal supporting multi-user cascaded transmission. Background Art

[0003] In recent years, with the expansion of the supply of mobile devices, wireless communication technologies that can provide fast wireless Internet services to mobile devices have attracted significant public attention. Wireless communication technologies allow mobile devices including smart phones, smart tablets, laptop computers, portable multimedia players, embedded devices, etc. to access the Internet wirelessly in a home or company or a specific service providing area.

[0004] One of the most well-known wireless communication technologies is wireless LAN technology. Since the initial wireless LAN technology was supported using a frequency of 2.4 GHz, the Institute of Electrical and Electronics Engineers (IEEE) 802.11 has commercialized or developed various technical standards. First, IEEE 802.11b supports a maximum communication speed of 11 Mbps when using a frequency in the 2.4 GHz band. 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, reduces the impact of interference compared to the significantly congested frequency in the 2.4 GHz band, and increases the communication speed up to a maximum of 54 Mbps by using orthogonal frequency division multiplexing (OFDM) technology. However, IEEE 802.11a has the disadvantage that the communication distance is shorter than that of IEEE 802.11b. In addition, IEEE 802.11g uses a frequency in the 2.4 GHz band similarly to IEEE 802.11b to achieve a maximum communication speed of 54 Mbps and satisfies backward compatibility to attract significant public attention, and further, it is superior to IEEE 802.11a in terms of communication distance.

[0005] In addition, as a technical standard established to overcome the limitations of communication speed pointed out as a weakness in wireless LAN, IEEE 802.11n has been provided. The purpose of IEEE 802.11n is to increase the speed and reliability of the network and extend the working distance of the wireless network. More specifically, IEEE 802.11n supports high throughput (HT) with a data processing speed of up to 540 Mbps or higher, and further, multiple-input multiple-output (MIMO) technology that uses multiple antennas on both sides of the transmitting unit and the receiving unit based on multiple antennas in order to minimize transmission errors and optimize data speed. In addition, the standard can use a coding scheme that sends multiple overlapping copies of each other in order to improve data reliability.

[0006] As the supply of wireless LAN has become active and further, the applications using wireless LAN have become diversified, the need for a new wireless LAN system that supports higher throughput (very high throughput (VHT)) than the data processing speed supported by IEEE 802.11n has drawn public attention. Among them, IEEE 802.11ac supports a wide bandwidth (80 to 160 MHz) in the 5 GHz frequency band. The IEEE 802.11ac standard is only defined within the 5 GHz frequency band, but the initial 11ac chipset will even support operation in the 2.4 GHz frequency band for backward compatibility with existing 2.4 GHz frequency band products. Theoretically, according to this standard, the wireless LAN speed of multiple stations can reach up to 1 Gbps at maximum and the maximum single-link speed can reach up to 500 Mbps at maximum. This is achieved by expanding the concept of the wireless interface accepted by 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). In addition, as a scheme for transmitting data by using the 60 GHz frequency band instead of the existing 2.4 GHz / 5 GHz, IEEE 802.11ad has been provided. IEEE 802.11ad is a transmission standard that provides a speed of up to 7 Gbps by using beamforming technology and is suitable for the transmission of high-bitrate moving images such as massive data or uncompressed HD video. However, since it is difficult for the 60 GHz frequency band to pass through obstacles, the disadvantage is that the 60 GHz frequency band can only be used between devices within a short-distance space.

[0007] Meanwhile, in recent years, as the next-generation wireless communication technology standard after 802.11ac and 802.11ad, discussions on providing high-efficiency and high-performance wireless communication technology in a high-density environment have been continuously carried out. That is, in the next-generation wireless communication technology environment, it is necessary to provide communication with high frequency efficiency indoors / outdoors in the presence of high-density terminals and basic terminals, and various technologies for realizing this communication are required.

[0008] In particular, as the number of devices using wireless communication technology increases, it is necessary to efficiently use a predetermined channel. Therefore, what is needed is a technology that can efficiently use bandwidth by simultaneously transmitting data between multiple terminals and a base terminal. SUMMARY OF THE INVENTION

[0009] TECHNICAL PROBLEM

[0010] An object of an embodiment of the present invention is to provide a wireless communication terminal that supports multi-user cascaded transmission.

[0011] TECHNICAL SOLUTION

[0012] According to an embodiment of the present invention, there is provided a wireless communication terminal that communicates wirelessly. The wireless communication terminal includes: a transceiver; and a processor, wherein the processor is configured to receive a downlink multi-user (DL MU) PPDU including information for uplink multi-user (UL MU) transmission from a base wireless communication terminal by using the transceiver, and transmit a UL MU PPDU to the base wireless communication terminal based on the information for UL MU transmission.

[0013] The information for UL MU transmission may be UL MU response information including transmission scheduling information of the UL MU PPDU, and the transmission scheduling information of the UL MU PPDU includes ACK, wherein the UL MU response information may be included in a MAC header.

[0014] The processor may be configured to set signaling information indicating whether spatial reuse (SR) transmission of the UL MU PPDU is allowed, so that SR transmission may not be allowed.

[0015] The processor may be configured to use a frequency bandwidth of the same size as the frequency bandwidth of the DL MU PPDU as the BW value of a transmission parameter TXVECTOR of the UL MU PPDU.

[0016] The processor may be configured to transmit the UL MU PPDU without using UL MU - multiple input multiple output (MIMO).

[0017] The processor may be configured to use a binary convolutional coding (BCC) code to transmit the UL MU PPDU.

[0018] When transmitting the UL MU PPDU, the processor may be configured to transmit a packet extension field according to a length indicated by the base wireless communication terminal.

[0019] The processor may be configured to transmit the UL MU PPDU without carrier sensing.

[0020] Whether carrier sensing is required when a wireless communication terminal transmits a UL MU PPDU can be determined by the length of the UL MU PPDU transmission duration.

[0021] An aggregated MAC protocol data unit (A-MPDU) including UL MU response information may not include a trigger MPDU that triggers a wireless communication terminal, and the UL MU response information of the wireless communication terminal indicates UL MU transmission.

[0022] UL MU transmission information may be a trigger MAC protocol data unit (MPDU) for triggering UL MU transmission of a wireless communication terminal.

[0023] An aggregated MPDU (A-MPDU) including a trigger MPDU may include a block ACK MPDU as a first MPDU and a trigger MPDU as a second MPDU.

[0024] An A-MPDU may include a block ACK request (BAR) MPDU as a last MPDU. According to an embodiment of the present invention, a wireless communication terminal that communicates wirelessly is provided. The wireless communication terminal includes: a transceiver; and a processor, wherein the processor is configured to send a downlink multi-user (DL MU) PPDU including information for uplink multi-user (UL MU) transmission to a plurality of wireless communication terminals by using the transceiver, and receive a UL MU PPDU sent based on the information for UL MU transmission from at least one of the plurality of wireless communication terminals.

[0025] The information for UL MU transmission may be UL MU response information including transmission scheduling information of the UL MU PPDU, and the transmission scheduling information of the UL MU PPDU includes an ACK, wherein the UL MU response information may be included in a MAC header.

[0026] The processor may be configured to signal a request for a MU block ACK for at least one MPDU included in the DL MU PPDU, and send a MU block ACK request (BAR) frame when a MU block ACK for at least one MPDU is not received.

[0027] The processor may be a trigger MAC protocol data unit (MPDU) for triggering UL MU transmission of a wireless communication terminal, and an aggregated MPDU (A-MPDU) including the trigger MPDU may include a block ACK MPDU as a first MPDU and a trigger MPDU as a second MPDU.

[0028] An A-MPDU may include a Block ACK Request (BAR) MPDU as the last MPDU.

[0029] According to an embodiment of the present invention, there is provided a method of operating a wireless communication terminal that communicates wirelessly. The method includes: receiving, from a base wireless communication terminal, a downlink multi-user (DL MU) PPDU including information for uplink multi-user (UL MU) transmission; and transmitting a UL MU PPDU to the base wireless communication terminal based on the information for UL MU transmission.

[0030] The information for UL MU transmission may be UL MU response information including transmission scheduling information of the UL MU PPDU, and the transmission scheduling information of the UL MU PPDU includes ACK, wherein the UL MU response information may be included in a MAC header.

[0031] Advantageous Effects

[0032] Embodiments of the present invention provide a communication method supporting multi-user cascaded transmission and a wireless communication terminal using the communication method. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Shows a wireless LAN system according to an embodiment of the present invention.

[0034] Figure 2 Shows a wireless LAN system according to another embodiment of the present invention.

[0035] Figure 3 Shows a block diagram illustrating a configuration of a station according to an embodiment of the inventive concept.

[0036] Figure 4 Shows a block diagram illustrating a configuration of an access point according to an embodiment of the present invention.

[0037] Figure 5 Shows a process of a station setting an access point and a link according to an embodiment of the present invention.

[0038] Figure 6 Shows a format of an A-MPDU for DL transmission by a base wireless communication terminal according to an embodiment of the present invention.

[0039] Figure 7 Shows a format of an A-MPDU for DL transmission by a base wireless communication terminal according to another embodiment of the present invention.

[0040] Figure 8 Shows an Ack policy and an Ack policy field indicated by a value of an Ack policy field of a QoS control field according to an embodiment of the present invention.

[0041] Figure 9 Illustrate the operation of a wireless communication terminal that receives a block ACK frame in a cascaded transmission according to an embodiment of the present invention.

[0042] Figure 10 Illustrate a method for a wireless communication terminal to transmit an A-MPDU according to an embodiment of the present invention.

[0043] Figure 11 Illustrate a method for a wireless communication terminal to transmit multicast data through an A-MPDU according to an embodiment of the present invention.

[0044] Figure 12 Illustrate the operation of a wireless communication terminal to change the receiver operation mode of the wireless communication terminal according to an embodiment of the present invention.

[0045] Figure 13 Illustrate the operation of transmitting a UL MU PPDU during a MU cascaded transmission according to an embodiment of the present invention.

[0046] Figure 14 Illustrate the operation of a wireless communication terminal according to an embodiment of the present invention. Detailed Description

[0047] Preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. However, the present invention can be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Parts irrelevant to the description are omitted in the drawings to clearly describe the present invention, and like reference numerals refer to like elements throughout.

[0048] In addition, when it is described that a thing includes (or contains or has) some elements, it should be understood that, without specific limitation, it may include (or contain or have) only those elements, or it may include (or contain or have) other elements as well as those elements.

[0049] This application claims the priority and benefits of Korean Patent Application Nos. 10-2016-0044466 (April 11, 2016) and 10-2016-0045120 (April 12, 2016) filed with the Korean Intellectual Property Office, and the embodiments and items mentioned in the corresponding applications are included in the detailed description of this application.

[0050] Figure 1FIG. is a diagram illustrating a wireless communication system according to an embodiment of the present invention. For convenience of description, embodiments of the present invention are described by a wireless LAN system. The wireless LAN system includes one or more basic service sets (BSSs), and a BSS represents a set of devices that have successfully synchronized with each other to communicate with each other. Generally, BSSs can be classified into infrastructure BSSs and independent BSSs (IBSSs), and Figure 1 illustrates the infrastructure BSS between them.

[0051] As Figure 1 illustrated in the figure, the infrastructure BSSs (BSS1 and BSS2) include one or more stations STA1, STA2, STA3, STA4, and STA5, access points PCP / AP-1 and PCP / AP-2 as stations providing a distribution service, and a distribution system (DS) connecting the multiple access points PCP / AP-1 and PCP / AP-2.

[0052] A station (STA) is a predetermined device including a medium access control (MAC) that follows the protocol of the IEEE 802.11 standard and a physical layer interface for a wireless medium, and in a broad sense includes a non-access point (non-AP) station and an access point (AP). Additionally, in this specification, the term "terminal" may be used to refer to a concept including a wireless LAN communication device such as a non-AP STA or an AP or both terms. A station for wireless communication includes a processor and a transceiver, and according to this embodiment, may further include a user interface unit and a display unit. The processor may generate a frame to be transmitted through a wireless network or process a frame received through a wireless network, and furthermore, execute various processes for controlling the station. In addition, the transceiver is functionally connected to the processor and transmits and receives frames through the wireless network for the station.

[0053] An access point (AP) is an entity that provides access to a distribution system (DS) for stations associated with it via a wireless medium. In an infrastructure BSS, communication between non-AP stations is in principle performed via an AP, but when a direct link is configured, direct communication can also be achieved even between non-AP stations. Meanwhile, in the present invention, an AP is used as a concept including a personal BSS coordination point (PCP) and may include, in a broad sense, a concept including a centralized controller, a base station (BS), a Node B, a base station transceiver system (BTS), and a site controller.

[0054] Multiple infrastructure BSSs can be connected to each other through a distribution system (DS). In this case, the multiple BSSs connected through the distribution system are called an extended service set (ESS).

[0055] Figure 2FIG. illustrates a stand-alone BSS as a wireless communication system according to another embodiment of the present invention. For convenience of description, another embodiment of the present invention will be described by a wireless LAN system. In Figure 2 In the embodiment of, the repeated description of parts identical or corresponding to the embodiment of Figure 1 will be omitted.

[0056] Since Figure 2 the BSS3 illustrated in is a stand-alone BSS and does not include an AP, all stations STA6 and STA7 are not connected to the AP. The stand-alone BSS is not permitted to access the distribution system and forms a complete network. In the stand-alone BSS, the corresponding stations STA6 and STA7 can be directly connected to each other.

[0057] Figure 3 is a block diagram illustrating the configuration of a station 100 according to an embodiment of the present invention.

[0058] As Figure 3 illustrated in, the station 100 according to an embodiment of the present invention may include a processor 110, a transceiver 120, a user interface unit 140, a display unit 150, and a memory 160.

[0059] First, the transceiver 120 transmits and receives wireless signals such as wireless LAN physical layer frames and may be embedded in the station 100 or provided externally. According to this embodiment, the transceiver 120 may include at least one transmit and receive module using different frequency bands. For example, the transceiver 120 may include transmit and receive modules having different frequency bands such as 2.4 GHz, 5 GHz, and 60 GHz. According to an embodiment, the station 100 may include a transmit and receive module using a frequency band of 6 GHz or higher and a transmit and receive module using a frequency band of 6 GHz or lower. The corresponding transmit and receive modules may perform wireless communication with an AP or an external station according to the wireless LAN standard of the frequency band supported by the corresponding transmit and receive module. The transceiver 120 may operate only one transmit and receive module at a time or operate multiple transmit and receive modules together simultaneously according to the performance and requirements of the station 100. When the station 100 includes multiple transmit and receive modules, each transmit and receive module may be implemented by an independent element or multiple modules may be integrated into one chip.

[0060] Next, the user interface unit 140 includes various types of input / output devices provided in the station 100. That is, the user interface unit 140 may receive user input by using various input devices and the processor 110 may control the station 100 based on the received user input. In addition, the user interface unit 140 may perform output based on the command of the processor 110 by using various output devices.

[0061] Next, the display unit 150 outputs an image on the display screen. The display unit 150 can output various display objects, such as the content executed by the processor 110 or the user interface, based on the control commands of the processor 110, etc. In addition, the memory 160 stores the control programs used in the station 100 and the data obtained from various results. The control program can include the access program required for the station 100 to access the AP or an external station.

[0062] The processor 110 of the present invention can execute various commands or programs and process the data in the station 100. In addition, the processor 110 can control the corresponding units of the station 100 and control the data transmission / reception between these units. According to an embodiment of the present invention, the processor 110 can execute a program for accessing the AP stored in the memory 160 and receive the communication configuration message sent by the AP. In addition, the processor 110 can read the information about the priority conditions of the station 100 included in the communication configuration message and request access to the AP based on the information about the priority conditions of the station 100. The processor 110 of the present invention can represent the main control unit of the station 100 and, according to this embodiment, the processor 110 can represent a control unit for individually controlling a certain component (e.g., the transceiver 120, etc.) of the station 100. The processor 110 can be a modulator and / or demodulator that modulates the wireless signal sent to the transceiver 120 and demodulates the wireless signal received from the transceiver 120. The processor 110 controls various operations of the wireless signal transmission / reception of the station 100 according to an embodiment of the present invention. Its detailed embodiments will be described below.

[0063] Figure 3 The station 100 illustrated in is a block diagram according to an embodiment of the present invention, where individual blocks are illustrated as logically distinct elements of the device. Therefore, the elements of the device can be installed in a single chip or multiple chips depending on the design of the device. For example, the processor 110 and the transceiver 120 can be integrated into a single chip or implemented as separate chips. In addition, in an embodiment of the present invention, some components of the station 100, such as the user interface unit 140 and the display unit 150, can be optionally provided in the station 100.

[0064] Figure 4 is a block diagram illustrating the configuration of the AP 200 according to an embodiment of the present invention.

[0065] As Figure 4 illustrated, the AP 200 according to an embodiment of the present invention can include a processor 210, a transceiver 220, and a memory 260. In Figure 4 among the components of the AP 200, the repeated description of the parts that are the same as or corresponding to the components of the Figure 2 station 100 will be omitted.

[0066] Reference Figure 4 , the AP 200 according to the present invention includes a transceiver 220 for operating a BSS in at least one frequency band. As described in the embodiments of Figure 3 , the transceiver 220 of the AP 200 may also include multiple transmit and receive modules using different frequency bands. That is, the AP 200 according to an embodiment of the present invention may include two or more transmit and receive modules among different frequency bands (e.g., 2.4 GHz, 5 GHz, and 60 GHz) together. Preferably, the AP 200 may include a transmit and receive module using a frequency band of 6 GHz or higher and a transmit and receive module using a frequency band of 6 GHz or lower. The corresponding transmit and receive modules may perform wireless communication with a station according to the wireless LAN standard of the frequency band supported by the corresponding transmit and receive module. The transceiver 220 may operate only one transmit and receive module at a time or operate multiple transmit and receive modules simultaneously according to the performance and requirements of the AP 200.

[0067] Next, the memory 260 stores control programs and various result-obtained data used in the AP 200. The control program may include an access program for managing access of a station. In addition, the processor 210 may control the corresponding units of the AP 200 and control data transmission / reception between these units. According to an embodiment of the present invention, the processor 210 may execute a program for accessing a station stored in the memory 260 and send a communication configuration message for one or more stations. In this case, the communication configuration message may include information about the access priority conditions of the corresponding station. In addition, the processor 210 performs access configuration according to the access request of the station. The processor 210 may be a modulator and / or demodulator that modulates a wireless signal sent to the transceiver 220 and demodulates a wireless signal received from the transceiver 220. The processor 210 controls various operations such as radio signal transmission / reception of the AP 200 according to the first embodiment of the present invention. Detailed embodiments thereof will be described below.

[0068] Figure 5 is a diagram schematically illustrating a process in which a STA sets a link with an AP.

[0069] Reference Figure 5, the link between the STA 100 and the AP 200 is generally set through three steps of scanning, authentication, and association. First, the scanning step is the step in which the STA 100 obtains access information of the BSS operated by the AP 200. The methods for performing scanning include a passive scanning method in which the AP 200 obtains information by using beacon messages (S101) sent periodically, and an active scanning method in which the STA 100 sends a probe request to the AP (S103) and obtains access information by receiving a probe response from the AP (S105).

[0070] The STA 100 that has successfully received wireless access information in the scanning step performs the authentication step by sending an authentication request (S107a) and receiving an authentication response from the AP 200 (S107b). After the authentication step is performed, the STA 100 performs the association step by sending an association request (S109a) and receiving an association response from the AP 200 (S109b).

[0071] Meanwhile, an 802.1X-based authentication step (S111) and an IP address acquisition step through DHCP (S113) can be additionally performed. In Figure 5 , the authentication server 300 is a server that processes 802.1X-based authentication for the STA 100 and can exist physically associated with the AP 200 or exist as a separate server.

[0072] In a specific embodiment, the AP 200 can be a wireless communication terminal that allocates communication medium resources and performs scheduling in an independent network (such as an ad hoc network) not connected to an external distribution service. In addition, the AP 200 can be at least one of a base station, an eNB, and a transmission point TP. The TP 200 can also be referred to as a basic communication terminal.

[0073] A transmission opportunity (TXOP) may include a downlink (DL) transmission and an uplink (UL) transmission. Specifically, a wireless communication terminal acting as an AP performs a DL transmission in a TXOP, and a non-AP wireless communication terminal may start a UL transmission after the DL transmission. Additionally, a non-AP wireless communication terminal performs a UL transmission in a TXOP, and a wireless communication terminal acting as an AP may start a DL transmission after the UL transmission. A TXOP includes both a DL transmission and a UL transmission, and the continuity between the DL transmission and the UL transmission is referred to as cascading. When transmitting a DL MU PPDU for cascaded transmission, the base wireless communication terminal may transmit information for UL MU transmission. Specifically, the base wireless communication terminal may transmit a DL MU PPDU including an MPDU containing UL MU response information. In this case, the UL MU response information may be information included in the MAC header. Specifically, the UL MU response information may be information for scheduling a trigger-based PPDU including an ACK. In a particular embodiment, the UL MU response information may be information for scheduling a trigger-based PPDU including an immediate ACK. Additionally, the base wireless communication terminal may transmit a DL MU PPDU including a trigger MPDU. A trigger MPDU is an MPDU that triggers the UL transmission of one or more wireless communication terminals. Multiple wireless communication terminals may simultaneously transmit UL PPDUs based on the information for UL MU transmission. Specifically, multiple wireless communication terminals may transmit OFDMA UL PPDUs based on the UL MU transmission information. Reference will be made to Figures 6 to 7 Describe in detail the information for UL MU transmission.

[0074] Figure 6 Illustrate the format of an A-MPDU for DL transmission by a base wireless communication terminal according to an embodiment of the present invention.

[0075] A Physical Layer Protocol Data Unit (PPDU) may include a PHY preamble, a payload, and Tail and Padding bits (T&P). The PHY preamble may include multiple fields. Specifically, the PHY preamble may include L-LTF and L-STF, which include training signals for legacy wireless communication terminals. Additionally, the PHY preamble may include an L-SIG field, which includes signaling information for legacy wireless communication terminals. The PHY preamble may also include an RL-SIG field to support automatic detection of the PPDU format. Additionally, the PHY preamble may include a HE-SIG-A field, which includes signaling information for non-legacy wireless communication terminals. Additionally, the PHY preamble may include a HE-SIG-B field, which includes signaling information for non-legacy wireless communication terminals. Additionally, the PHY preamble may include HE-LTF and HE-STF, which include training signals for non-legacy wireless communication terminals. Additionally, the PHY preamble may include a service field. Specifically, the format of the PPDU may be the same as Figure 6 the format of the embodiment of (a).

[0076] A PPDU may include one or more MPDUs. An MPDU may include a Frame Control field, which includes information about frame control. Additionally, an MPDU may include a Duration / ID field, which indicates the identifier of the MPDU or the TXOP duration set by the MPDU. Furthermore, an MPDU may include at least one of an Address 1 field, an Address 2 field, an Address 3 field, and an Address 4 field, which indicate addresses related to the transmission and reception of the MPDU. Additionally, an MPDU may include a Sequence Control field indicating information about the sequence. Additionally, the MPDU field may include a QoS Control field for QoS control. Additionally, an MPDU may include an HT Control field for High Throughput (HT) control. Additionally, an MPDU may include a Frame Body field containing an MSDU. Moreover, an MPDU may include an FCS field for determining whether the MPDU includes an error. Specifically, the format of the MPDU may be the same as Figure 6 the format of the embodiment of (b).

[0077] The QoS Control field may include a TID field indicating the TID of the data to which the QoS Control field is applied. Additionally, the QoS Control field may include an EOSP field indicating the end of the current service period. The QoS Control field may include an ACK Policy field, which indicates the ACK transmission method to be sent by a terminal that has received the data to which the QoS field is applied. The values indicated by the ACK Policy field will be described in detail with reference to Figure 8 Additionally, the QoS Control field may include an A-MSDU Presence field indicating the type of A-MSDU. Additionally, the QoS Control field may include an AP PS Buffer Status field indicating the PS buffer status. Specifically, the format of the QoS Control field may be the same asFigure 6 The format of the embodiment of (c) is the same.

[0078] The HT control field may include a VHT field indicating whether the information indicated by the HT control field is very high throughput (VHT) control information. Additionally, the HT control field may include a HE field indicating whether the information indicated by the HT control field is HE control information. Additionally, the HT control field may include an aggregation control (A-Control) field including a plurality of subfields representing information regarding control.

[0079] The subfields included in the A control field may include a control ID field for identifying the control information included in the subfield and a control information field for indicating the control information included in the subfield. Specifically, the subfields included in the A control field include UL MU response information, which is information for an uplink (UL) MU PPDU response to a downlink (DL) multi-user (MU) PPDU. In this case, the value of the control ID field may be 0. In a specific embodiment, the UL MU response information may be used in a DL SU PPDU. This will be described with reference to Figure 12 this. Additionally, the subfields included in the A control field may include information regarding a change in the receiver operation mode. Specifically, the information regarding the change in the receiver operation mode may be a receiver operation mode indication (ROMI) of the operation mode to be changed. In this case, the value of the control ID field may be 1. Furthermore, the subfields included in the A control field may include information regarding link adaptation. In this case, the value of the control ID field may be 2.

[0080] The base wireless communication terminal may use the UL MU response information to perform MU cascaded transmission with a plurality of wireless communication terminals that receive the UL MU response information. Specifically, when sending data via a DL MU PPDU, the base wireless communication terminal may send the UL MU response information via the A control field. The plurality of wireless communication terminals that have received the DL MU PPDU from the base wireless communication terminal may send UL MU PPDUs based on the UL MU response information. The base wireless communication terminal may be allowed to send the UL MU response information to wireless communication terminals having the ability to support UL MU transmission based on the UL MU response information. Additionally, the base wireless communication terminal may not be allowed to simultaneously send a triggered MPDU and the UL MU response information to the same wireless communication terminal in a single PPDU. This will be described with reference to Figure 7 this.

[0081] Figure 7 Shows the format of an A-MPDU used for DL transmission by a base wireless communication terminal according to another embodiment of the present invention.

[0082] The basic wireless communication terminal can transmit at least one of a control MPDU and a management MPDU together with a data MPDU through A-MPDU. Accordingly, the basic wireless communication terminal can transmit a trigger MPDU among the control MPDUs together with the data MPDU.

[0083] The trigger MPDU can include a frame control field including information on frame control. Additionally, the trigger MPDU can include a duration / ID field indicating an identifier of the MPDU or a TXOP duration set by the MPDU. Additionally, the trigger MPDU can include an RA field indicating a receiver address of the trigger MPDU and a TA field indicating a transmitter address of the trigger MPDU.

[0084] Furthermore, the trigger MPDU can include a common information field indicating information common to a plurality of wireless communication terminals that receive the trigger MPDU. Additionally, the trigger MPDU can include a per-user information field indicating information about each of the plurality of wireless communication terminals that receive the trigger MPDU. Moreover, the trigger MPDU can include padding for alignment during transmission. Moreover, the trigger MPDU can include an FCS field for determining whether the MPDU includes an error. Specifically, the format of the trigger MPDU can be the same as Figure 7 the format of the embodiment of (b).

[0085] The common information field may include a length field indicating the length of the UL MU PPDU transmitted based on the trigger MPDU. Specifically, the length field may indicate the value of the L-SIG length field of the UL MU PPDU transmitted based on the trigger MPDU. In addition, the common information field may include a concatenation indication field indicating whether concatenated transmission is performed in the TWT operation and the power saving operation. Additionally, the common information field may include a CS required field indicating whether carrier sensing is required when the wireless communication terminal receiving the trigger MPDU transmits the UL MU PPDU based on the trigger MPDU. Additionally, the common information field may include a spatial reuse field indicating information related to the SR operation of the UL MU PPDU transmitted based on the trigger MPDU. Additionally, the common information field may include BW field information indicating the bandwidth of the HE SIG-A field of the UL MU PPDU transmitted based on the trigger MPDU. The BW field indicates the BW field value of the transmission parameter TXVECTOR of the UL MU PPDU. Specifically, the BW field may signal one of the values of 20, 40, 80, and 160 (80 + 80) MHz. Additionally, the common information field may include a CP / LTF type field indicating the LTF type of the UL MU PPDU transmitted based on the trigger MPDU. Additionally, the common information field may include a MU-MIMO and MU-MIMO LTF mode field indicating the LTF mode of the UL MU PPDU transmitted based on the trigger MPDU. Additionally, the common information field may include an LTF number field indicating the number of LTF symbols of the UL MU PPDU transmitted based on the trigger MPDU. Additionally, the common information field may include an STBC field indicating whether STBC coding is applied to the UL MU PPDU transmitted based on the trigger MPDU. Additionally, the common information field may include an LDPC extra field indicating the status of the LDPC additional symbol segments in the UL MU PPDU transmitted based on the trigger MPDU. Additionally, the common information field may include an AP TX power field indicating the transmission power used for the transmission of the UL MU PPDU transmitted based on the trigger MPDU. In this case, the AP TX power field may indicate the transmission power in units of 20 MHz. Additionally, the common information field may include a packet extension field indicating the packet extension length of the UL MU PPDU transmitted based on the trigger MPDU. Additionally, the common information field may include a trigger type field indicating the type of the trigger MPDU. Additionally, the common information field may include a trigger-related common information field, and this information varies according to the type of the trigger MPDU.

[0086] If the type of the triggering MPDU indicated by the triggering type field is MU-BAR, the triggering-related common information field may include information about groupcast with retries (GCR). Specifically, the triggering-related common information field may include a GCR indication field indicating whether the MU-BAR is a GCR MU-BAR. Additionally, the triggering-related common information field may include a GCR address field indicating the GCR address. The format of the specific common information field may be the same as that of the embodiment of Figure 7 (c).

[0087] The per-user information field may include a user ID field that identifies the wireless communication terminal corresponding to the per-user information field. In addition, the per-user information field may include an RU allocation field that indicates information about the resource unit (RU) used by the wireless communication terminal corresponding to the user information field when transmitting a UL MUPPDU. Additionally, the per-user information field may include a coding type field that indicates the coding type to be used when the wireless communication terminal corresponding to the per-user information field transmits a UL MU PPDU. Additionally, the per-user information field may include an MCS field that indicates information about the modulation and coding scheme (MCS) used by the wireless communication terminal corresponding to the user information field when transmitting a UL MU PPDU. Additionally, the per-user information field may include a DCM field that indicates whether the wireless communication terminal corresponding to the per-user information field uses dual-carrier modulation when transmitting a UL MU PPDU. Additionally, the per-user information field may include an SS allocation field that indicates information about the spatial stream used by the wireless communication terminal corresponding to the per-user information field when transmitting a UL MU PPDU. In addition, the per-user information field may include a target RSSI field that indicates the target received signal strength, which is the signal strength for correctly receiving the ULMU PPDU transmission signal transmitted by the wireless communication terminal corresponding to the per-user information field. In addition, the per-user information field may include a triggering-related per-user information field that includes information according to the triggering type.

[0088] If the type of the triggered MPDU indicated by the trigger type field is MU-BAR, the trigger-related per-user information field may include a BAR control field and a BA information field. The BAR control field may include a BARAck policy field indicating the ACK method specified for the MU-BAR. Additionally, the BAR control field may include a multi-TID field indicating whether an ACK transmission for multiple TIDs is requested. Additionally, the BAR control field may include a compressed bitmap field indicating whether a compressed bitmap type of block ACK transmission is requested. Additionally, the BAR control field may include a GCR field indicating whether a GCR block ACK transmission is requested. Additionally, the BAR control field may include a TID / Num TID field indicating information about the TID of the data for which an ACK transmission is requested. The information represented by the BA information field depends on the BAR control field. Specifically, when the value of the multi-TID field of the BAR control field is 1, the BAR control field may request an ACK for multiple TIDs. In this case, the BA information field may include a per-TID information field indicating the TID of the data for which an ACK is requested and a BA SSN field indicating the first sequence number for which an ACK is requested by the block ACK. Further, when the value of the GCR field is 1, the MU-BAR may request a GCR transmission. In this case, the BA information field may include a BA SSN field indicating the first sequence number for which an ACK is requested and a GCR address field indicating the GCR address. In another specific embodiment, the BA information field may include a per-TID information field indicating the TID of the data for which an ACK is requested and a BA SSN field indicating the first sequence number for which an ACK is requested by the block ACK. The common information field includes a GCR address field to reduce unnecessary repeated transmissions. The specific format of the per-user information field may be as shown in Figure 7 (d).

[0089] Figure 8 Illustrates an Ack policy and an Ack policy field indicated by the value of the Ack policy field of the QoS control field according to an embodiment of the present invention.

[0090] A wireless communication terminal that has transmitted data may request a wireless communication terminal that has received the data to send an ACK and specify the format of the ACK. The wireless communication terminal that has transmitted data may request ACK transmission from the wireless communication terminal that has received the data through the Ack Policy field in the QoS control field of the MAC header and specify the format of the ACK. Specifically, the wireless communication terminal that has transmitted data may request immediate transmission of an ACK frame or immediate transmission of a block ACK frame from the wireless communication terminal that has received the data. In this case, the wireless communication terminal that has transmitted data may set the value of the Ack Policy field in the QoS control field to 0 (00b). The immediate transmission request may be a request to send a response within a specific time period starting from when the data is received or starting from when the request is received. In a specific embodiment, the time may be a Short Inter-Frame Space (SIFS). Additionally, the wireless communication terminal that has transmitted data may request the wireless communication terminal that has received the data to send an implicit ACK or send a PSMP ACK. In this case, the wireless communication terminal that has transmitted data may set the value of the Ack Policy field in the QoS control field to 1 (01b). Additionally, the wireless communication terminal may signal to the wireless communication terminal that has received the data that it does not request the sending of an ACK. In this case, the wireless communication terminal that has transmitted data may set the value of the Ack Policy field in the QoS control field to 2 (10b). Additionally, the wireless communication terminal that has transmitted data may signal to the wireless communication terminal that has received the data that the wireless communication terminal that has transmitted the data will request transmission of a block ACK frame. In this case, the wireless communication terminal that has transmitted data may set the value of the Ack Policy field in the QoS control field to 3 (11b). Furthermore, the wireless communication terminal that has transmitted data may request the wireless communication terminal that has received the data to send a MU ACK. In this case, the wireless communication terminal that has transmitted data may set the value of the Ack Policy field in the QoS control field to 1 (01b).

[0091] Additionally, the wireless communication terminal that has transmitted data sends a BAR frame to the wireless communication terminal that has received the data to request immediate transmission of a block ACK. Additionally, the wireless communication terminal that has transmitted data sends a MU-BAR frame to the wireless communication terminal that has received the data to request immediate transmission of a MU block ACK.

[0092] In a MU cascade transmission, the base wireless communication terminal may request immediate transmission of a MU block ACK frame for data transmission to the wireless communication terminal that has received the data. Specifically, the base wireless communication terminal may request immediate transmission of a MU block ACK that is for data transmission to the wireless communication terminal that has received the data through the Ack Policy field in the QoS control field or the MU-BAR frame. Reference will be made to Figure 9Methods for setting the value of the Ack policy field in a cascaded transmission and methods for transmitting / receiving block ACK frames are described.

[0093] Figure 9 Operations of a wireless communication terminal receiving a block ACK frame in a cascaded transmission according to an embodiment of the present invention are shown.

[0094] In the absence of information for a separate UL MU transmission, a wireless communication terminal transmitting a SU PPDU may request an immediate ACK transmission of at least one A-MPDU included in the SU PPDU from the wireless communication terminal receiving the SU PPDU. In this case, the wireless communication terminal transmitting the SU PPDU may set the value of the Ack policy field in the QoS control field to 0 (00b). This is because the wireless communication terminal transmitting the UL SU PPDU does not require additional resource allocation information for UL MU transmission.

[0095] The wireless communication terminal transmitting the SU PPDU may send UL MU response information to the wireless communication terminal receiving the SU PPDU and trigger the wireless communication terminal receiving the SU PPDU to send data and ACK together. When the MPDU included in the SU PPDU includes UL MU response information, the wireless communication terminal receiving the SU PPDU may send data and ACK together.

[0096] The wireless communication terminal receiving the SU PPDU may send data during the uplink transmission duration indicated by the information for UL MU transmission. Specifically, the wireless communication terminal receiving the SU PPDU may send data during a duration equal to or shorter than the uplink transmission duration indicated by the information for UL MU transmission. In this case, the uplink transmission duration may be the duration indicated by the UL PPDU length field of the above UL MU response information. The uplink transmission duration may be the duration indicated by the length field of the common information field triggering the MPDU. In this case, the uplink transmission duration may be limited to the TXOP duration obtained by the wireless communication terminal transmitting the SU PPDU. Accordingly, the wireless communication terminal transmitting the SU PPDU may set the uplink transmission duration within the TXOP duration obtained by the wireless communication terminal transmitting the SU PPDU.

[0097] In addition, a wireless communication terminal that receives an SU PPDU may use the MCS indicated by the information for UL MU transmission to send ACK and data. In another specific embodiment, a wireless communication terminal that receives an SU PPDU may determine that the MCS indicated by the information for UL MU transmission is the MCS recommended by the wireless communication terminal that transmits the SU PPDU, and may send ACK and data using an MCS other than the MCS indicated by the information for UL MU transmission. In this case, ACK and data may be sent at the primary rate calculated by the wireless communication terminal that receives the SU PPDU.

[0098] In addition, a wireless communication terminal that receives an SU PPDU may not decode the RU allocation information included in the information for UL MU transmission. The RU allocation information may be the information represented by the RU allocation field included in the UL MU response information. In addition, the RU allocation information may be the information represented by the RU allocation field of the per-user information field that triggers the MPDU.

[0099] In addition, when the base wireless communication terminal triggers UL SU PPDU transmission, the base wireless communication terminal may be allowed to send the information for UL MU transmission to a wireless communication terminal that does not have the ability to support UL MU transmission.

[0100] In Figure 9 In the embodiment of (a), the base wireless communication terminal sends an SU PPDU including data MPDUs (Data1, Data2) containing UL MU response information to the first station STA1. In this case, the base wireless communication terminal sets the acknowledgment policy field value of the QoS control field to 0 (00b). The first station STA1 receives the SU PPDU from the base wireless communication terminal. The first station STA1 sends the data MPDU together based on the UL MU response information, and at the same time sends a block ACK frame for the received MPDU (Data1 / Data2) based on the Ack policy field of the QoS control field.

[0101] When sending an A-MPDU, the base wireless communication terminal may configure the HT control fields of all the MPDUs included in the A-MPDU to be the same. In this case, the MPDUs included in the A-MPDU may have different Ack policy field values. In this case, when the wireless communication terminal that receives the A-MPDU only receives one data MPDU, the wireless communication terminal that receives the A-MPDU may not send an ACK according to the ACK policy field of the QoS control field.

[0102] In Figure 9In the embodiment of (b), the basic wireless communication terminal transmits a DL MU PPDU to the first station STA1 to the third station STA3. In this case, the basic wireless communication terminal sets the ACK policy field values of the QoS control fields of the MPDUs transmitted to the first station STA1, the second station STA2, and the third station STA3 to be different from each other. The basic wireless communication terminal sets the ACK policy field value of the first data MPDU (Data1) to be transmitted to the second station STA2 to 1 (01b). In addition, the basic wireless communication terminal sets the ACK policy field value of the second data MPDU (Data2) to be transmitted to the second station STA2 to 3 (11b). According to an embodiment of the present invention, since the HT control field values of all MPDUs included in the A-MPDU must be the same, the basic wireless communication terminal inserts UL MU response information into the HT control field of the first data MPDU (Data1) and the HT control field of the second data MPDU (Data2). In this case, the second station STA2 only receives the second data MPDU (Data2) from the basic wireless communication terminal. However, since the ACK policy field value of the second data MPDU (Data2) is 3 (11b), the second station STA2 does not transmit a block ACK frame until it receives another BAR MPDU. In this case, the UL MU response information set in the second data MPDU (Data2) transmitted from the basic wireless communication terminal to the second station STA2 is not used. Therefore, when transmitting an A-MPDU, the basic wireless communication terminal can set the HT control fields of all MPDUs included in the A-MPDU differently.

[0103] If the base wireless communication terminal requests immediate transmission of the MU block ACK frame from one or more wireless communication terminals but fails to receive the MU block ACK frame, the base wireless communication terminal may send a MU-BAR frame to one or more wireless communication terminals. Specifically, if the base wireless communication terminal requests transmission of the MU-block ACK frame by setting the Ack policy field of the HT control field to 1 (01b) but fails to receive the MU-block ACK frame, the base wireless communication terminal may send the MU-BAR frame to one or more wireless communication terminals. In a particular embodiment, if the base wireless communication terminal sends UL MU response information for MU block ACK transmission to one or more wireless communication terminals, and sets the Ack policy field of the HT control field to 1 (01b) to request MU block ACK frame transmission but does not receive the MU block ACK frame, the base wireless communication terminal may send a MU-BAR frame to one or more wireless communication terminals. Additionally, if the base wireless communication terminal sends a MU-BAR MPDU for sending the MU block ACK to one or more wireless communication terminals, and sets the Ack policy field of the HT control field to 1 (01b) to request MU block ACK frame transmission but does not receive the MU block ACK frame, the base wireless communication terminal may send a MU-BAR frame to one or more wireless communication terminals.

[0104] In Figure 9In the embodiment of (c), the basic wireless communication terminal transmits A-MPDUs to the first station STA1 to the third station STA3. In this case, the basic wireless communication terminal sets the Ack policy field of the HT control field of some MPDUs transmitted to the first station STA1 to the third station STA3 to 1 (01b). In addition, the basic wireless communication terminal transmits UL MU response information for MU block ACK frame transmission to the first station STA1 and the third station STA3, and transmits a trigger MPDU for MU block ACK frame transmission to the second station SAT2. In this case, the first station STA1 fails to receive the UL MU response information from the basic wireless communication terminal. Moreover, the second station STA2 fails to receive the trigger MPDU from the basic wireless communication terminal. Therefore, only the third station STA3 immediately transmits a MU block ACK frame to the basic wireless communication terminal. The basic wireless communication terminal transmits a MU-BAR frame to the first station STA1 to the third station STA3 to request the transmission of the MU block ACK frame. In this case, the basic wireless communication terminal sets the Ack policy field to 1 (01b) for the first station STA1 and the second station STA2, but requests the third station STA3 to transmit ACKs for the MPDUs for which the block ACKs have not been received, and requests the third station STA3 to transmit ACKs for the MPDUs with the Ack policy field set to 3 (11b). The first to third stations STA1 to STA3 transmit MU block ACK frames to the basic wireless communication terminal.

[0105] Figure 10 A method for a wireless communication terminal to transmit A-MPDUs according to an embodiment of the present invention is shown.

[0106] As described above, the wireless communication terminal may transmit at least one of a control MPDU and a management MPDU together with a data MPDU through an A-MPDU. The wireless communication terminal may transmit an A-MPDU including a block ACK MPDU, a BAR MPDU, and a data MPDU. When the wireless communication terminal transmits an A-MPDU including a block ACK MPDU, a BAR MPDU, and a data MPDU, the wireless communication terminal may transmit the block ACK MPDU to the first MPDU of the A-MPDU. Additionally, when the wireless communication terminal transmits an A-MPDU including a block ACK MPDU, a BAR MPDU, and a data MPDU, the wireless communication terminal may transmit the BAR MPDU to the last MPDU of the A-MPDU. Specifically, when the wireless communication terminal transmits an A-MPDU including a block ACK MPDU, a BAR MPDU, and a data MPDU, the wireless communication terminal may transmit the block ACK MPDU to the first MPDU of the A-MPDU and transmit the BAR MPDU to the last MPDU of the A-MPDU. The wireless communication terminal that receives the A-MPDU may receive the block ACK MPDU and remove the MPDUs indicated by the block ACK MPDU in the transmission buffer. Specifically, the wireless communication terminal may transmit an A-MPDU including a block ACK MPDU as the first MPDU and a BAR MPDU as the last MPDU, as shown in Figure 10 (a). In this case, the wireless communication terminal that receives the A-MPDU may transmit an A-MPDU including a block ACK MPDU as the first MPDU and a BAR MPDU as the last MPDU in response to the received A-MPDU.

[0107] The base wireless communication terminal may transmit a trigger MPDU together with a data MPDU. In this case, the trigger MPDU indicates resource allocation information for uplink transmission. Specifically, the base wireless communication terminal may transmit an A-MPDU including a trigger MPDU, a block ACK MPDU, a BAR MPDU, and a data MPDU. In a specific embodiment, when the base wireless communication terminal transmits an A-MPDU including a trigger MPDU, a block ACK MPDU, a BAR MPDU, and a data MPDU, the base wireless communication terminal may transmit the trigger MPDU as the first MPDU of the A-MPDU. Additionally, when the base wireless communication terminal transmits an A-MPDU including a trigger MPDU, a block ACK MPDU, a BAR MPDU, and a data MPDU, the base wireless communication terminal may transmit the block ACK MPDU as the second MPDU of the A-MPDU. Specifically, when the base wireless communication terminal transmits an A-MPDU including a trigger MPDU, a block ACK MPDU, a BAR MPDU, and a data MPDU, as shown in Figure 10As in the embodiment of (b), the basic wireless communication terminal may transmit an A-MPDU including a trigger MPDU that is the first MPDU of the A-MPDU, a block ACK MPDU that is the second MPDU of the A-MPDU, and a BAR MPDU that is the last MPDU. In this case, the wireless communication terminal that receives the A-MPDU may transmit an A-MPDU including a block ACK MPDU that is the first MPDU and a BAR MPDU that is the last MPDU in response to the received A-MPDU. When the basic wireless communication terminal transmits a trigger MPDU that is the first MPDU of the A-MPDU, it is possible to reduce the processing burden of the wireless communication terminal that receives the A-MPDU until the uplink transmission start time point for preparing for uplink transmission. However, in such an embodiment, the wireless communication terminal that receives the A-MPDU may remove the MPDU received by the basic wireless communication terminal relatively late in the transmission buffer.

[0108] In another specific embodiment, when the basic wireless communication terminal transmits an A-MPDU including a trigger MPDU, a block ACK MPDU, a BAR MPDU, and a data MPDU, the basic wireless communication terminal may transmit the block ACK MPDU as the first MPDU of the A-MPDU. In addition, when the basic wireless communication terminal transmits an A-MPDU including a trigger MPDU, a block ACK MPDU, a BAR MPDU, and a data MPDU, the basic wireless communication terminal may transmit the trigger MPDU as the second MPDU of the A-MPDU. In addition, when the basic wireless communication terminal transmits an A-MPDU including a trigger MPDU, a block ACK MPDU, a BAR MPDU, and a data MPDU, the basic wireless communication terminal may transmit the BAR MPDU as the last MPDU of the A-MPDU. Specifically, when the basic wireless communication terminal transmits an A-MPDU including a trigger MPDU, a block ACK MPDU, a BAR MPDU, and a data MPDU, as Figure 10As in the embodiment of (c), the base wireless communication terminal may transmit an A-MPDU including a block ACK MPDU as a first MPDU of an A-MPDU, a trigger MPDU including a second MPDU of the A-MPDU, and a BAR MPDU as a last MPDU. In this case, the wireless communication terminal receiving the A-MPDU may transmit an A-MPDU including a block ACK MPDU as a first MPDU and a BAR MPDU as a last MPDU in response to the received A-MPDU. When the base wireless communication terminal transmits a block ACK MPDU to the first MPDU of the A-MPDU and transmits a trigger MPDU to the second MPDU of the A-MPDU, the processing burden on the wireless communication terminal receiving the A-MPDU for preparing for uplink transmission until the uplink transmission start time point can be reduced. In this case, the wireless communication terminal receiving the A-MPDU can relatively quickly remove the MPDU received from the base wireless communication terminal in the transmission buffer.

[0109] Figure 11 A method for a wireless communication terminal to transmit multicast data through an A-MPDU according to an embodiment of the present invention is shown.

[0110] As referred to Figure 7 As described, the base wireless communication terminal may transmit a MU-BAR frame, which is a variant of a trigger frame. Specifically, the base wireless communication terminal may transmit a MU-BAR frame and request transmission of MU-block ACKs from a plurality of wireless communication terminals that receive the MU-BAR frame. The base wireless communication terminal may simplify the process required to receive block ACK frames from a plurality of wireless communication terminals. In Figure 11 In the embodiment of (a), the base wireless communication terminal transmits multicast data to the first station STA1 to the third station STA3. In this case, the base wireless communication terminal sets the Ack policy field of the QoS control field to 3 (11b) to signal the first station STA1 to the third station STA3 to request transmission of block ACK frames. The base wireless communication terminal transmits a MU-BAR frame to the first station STA1 to the third station STA3. The first to third stations STA1 to STA3 transmit MU block ACK frames to the base wireless communication terminal.

[0111] The base wireless communication terminal may transmit an A-MPDU including a MU-BAR MPDU and a data MPDU. When the base wireless communication terminal transmits an A-MPDU including a MU-BAR MPDU and a data MPDU, the base wireless communication terminal may transmit the MU-BAR MPDU as the last MPDU of the A-MPDU. In this case, the base wireless communication terminal may transmit padding after the MU-BAR MPDU transmission. In Figure 11In the embodiment of (b), the infrastructure wireless communication terminal transmits multicast data to the first station STA1 to the third station STA3. In this case, the infrastructure wireless communication terminal sets the Ack policy field of the QoS control field to 3 (11b) to signal the first station STA1 to the third station STA3 to request the transmission of a block ACK frame. The infrastructure wireless communication terminal transmits an A-MPDU including a MU-BAR frame and a data frame to the first station STA1 to the third station STA3. In this case, the infrastructure wireless communication terminal transmits the MU-BAR frame as the last MPDU of the A-MPDU. In addition, the infrastructure wireless communication terminal transmits padding after transmitting the MU-BAR frame. The first to third stations STA1 to STA3 transmit a MU block ACK frame to the infrastructure wireless communication terminal. Through this embodiment, the infrastructure wireless communication terminal can reduce the processing burden of the wireless communication terminals receiving the A-MPDU to transmit the MU block ACK.

[0112] In another specific embodiment, when the infrastructure wireless communication terminal transmits an A-MPDU including a MU-BAR MPDU and a data MPDU, the infrastructure wireless communication terminal may transmit the MU-BAR MPDU as the first MPDU of the A-MPDU. As described above, since the MU-BAR frame is a variant of the trigger frame, the infrastructure wireless communication terminal can process the MU-BAR MPDU in the same way as processing a trigger MPDU when transmitting an A-MPDU including the MU-BAR MPDU. In Figure 11 In the embodiment of (c), the infrastructure wireless communication terminal transmits multicast data to the first station STA1 to the third station STA3. In this case, the infrastructure wireless communication terminal sets the Ack policy field of the QoS control field to 3 (11b) to signal the first station STA1 to the third station STA3 to request the transmission of a block ACK frame. The infrastructure wireless communication terminal transmits an A-MPDU including a MU-BAR frame and a data frame to the first station STA1 to the third station STA3. In this case, the infrastructure wireless communication terminal transmits the MU-BAR frame as the first MPDU of the A-MPDU. The first to third stations STA1 to STA3 transmit a MU block ACK frame to the infrastructure wireless communication terminal. Through this embodiment, the infrastructure wireless communication terminal can reduce the processing burden of the wireless communication terminals receiving the A-MPDU to prepare for the MU block ACK transmission until the MU block ACK transmission start time point. In this embodiment, the wireless communication terminals receiving the A-MPDU may need to configure the block ACK frame based on the BAR MPDU, and then configure the block ACK frame according to whether MPDUs are transmitted through the A-MPDU after the BAR MPDU. Therefore, the processing burden of the wireless communication terminals receiving the A-MPDU to transmit the block ACK frame may increase.

[0113] The basic wireless communication terminal may transmit an A-MPDU instead of a MU-BARMPDU including a trigger MPDU and multiple BAR MPDUs. In this case, the basic wireless communication terminal may include the trigger MPDU as the first MPDU, which is not a MU-BARMPDU, and may transmit the multiple BAR MPDUs after transmitting all other MPDUs including the A-MPDU. In this case, the receiver address of the BAR MPDU may be different from the receiver address of the data MPDU including the multicast data. To this end, the basic wireless communication terminal may create an exception to the principle of transmitting all MPDUs having the same receiver address within one A-MPDU. In another specific embodiment, the basic wireless communication terminal may transmit a multi-STA BAR MPDU including BAR information for multiple wireless communication terminals instead of the multiple BAR MPDUs. In this case, the multi-STA BAR MPDU may have the same receiver address as the data MPDU including the multicast data. Additionally, the BAR information of each of the multiple wireless communication terminals included in the multi-STA BAR MPDU may be distinguished by the AID of each of the multiple wireless communication terminals. In Figure 11 In the embodiment of (d), the basic wireless communication terminal transmits multicast data to the first station STA1 to the third station STA3. In this case, the basic wireless communication terminal sets the Ack policy field of the QoS control field to 3 (11b) to signal the first station STA1 to the third station STA3 to request the transmission of a block ACK frame. The basic wireless communication terminal transmits an A-MPDU including a trigger frame, three BAR frames, and a data frame to the first station STA1 to the third station STA3. In this case, the basic wireless communication terminal transmits the trigger frame to the first MPDU of the A-MPDU, and then transmits the three BAR MPDUs after transmitting all other MPDUs included in the A-MPDU. Additionally, the basic wireless communication terminal may transmit a multi-STA BAR MPDU including BAR information about the first station STA1 to the third station STA3 instead of the three BAR MPDUs. The first to third stations STA1 to STA3 transmit a MU block ACK frame to the basic wireless communication terminal. Through this embodiment, the wireless communication terminal receiving the A-MPDU can effectively prepare for the block ACK frame transmission.

[0114] Figure 12 An operation of a wireless communication terminal changing a receiver operation mode of the wireless communication terminal according to an embodiment of the present invention is shown.

[0115] A wireless communication terminal may send information about a change in operation mode through an HT control field. Specifically, the wireless communication terminal may send information about a change in operation mode through an MPDU included in an SU PPDU. In this case, the information about the change in operation mode may be a Receiver Operation Mode Indicator (ROMI). In yet another specific embodiment, the information about the change in operation mode may be a Transmitter Operation Mode Indicator (TOMI). The information about the change in operation mode includes information about parameters related to the operation mode that the wireless communication terminal sending the information about the change in operation mode is to change to. Specifically, the information about the change in operation mode may include information about the number of receivable spatial streams. Additionally, the information about the change in operation mode may include information about the receivable frequency bandwidth. In particular, the information about the change in operation mode may include information about the number of transmittable spatial streams. Additionally, the information about the change in operation mode may include information about the transmittable frequency bandwidth. When the wireless communication terminal that receives the information about the change in operation mode sends an ACK, the wireless communication terminal that sends the information about the change in receiver operation mode may change the operation mode of the wireless communication terminal for sending the ACK. In this case, the wireless communication terminal that sends the information about the change in operation mode may change the operation mode after the elapse of a transition time starting from when the ACK is received.

[0116] In Figure 12 Example (a), the base wireless communication terminal sends an A-MPDU including two data MPDUs each containing a ROMI to a first station STA1. In this case, the base wireless communication terminal sets the ACK policy field value of the QoS control field of the data MPDU to 0 (00b) to request immediate ACK transmission for the data MPDU. The first station STA1 sends a Block ACK frame indicating receipt of the two data MPDUs included in the A-MPDU. The base wireless communication terminal receives the Block ACK frame from the first station STA1 and changes the receiver operation mode.

[0117] In Figure 12 Example (b), the base wireless communication terminal sends an A-MPDU including two data MPDUs each containing a ROMI to a first station STA1. In this case, the base wireless communication terminal sets the ACK policy field value of the QoS control field of the data MPDU to 3 (11b) to signal that the base wireless communication terminal will request transmission of a Block ACK frame for the data MPDU. Then, the base wireless communication terminal sends a BAR frame to request immediate transmission of a Block ACK frame for the data MPDU.

[0118] Compared with Figure 12 Example (b), the base wireless communication terminal may Figure 12In the embodiment of (a), the receiver operation mode is changed more quickly. Accordingly, the wireless communication terminal may request an immediate ACK transmission for an MPDU including information on the operation mode change. Specifically, the wireless communication terminal may set the ACK policy field value of the QoS control field of the MPDU including information on the operation mode change to 0 (00b).

[0119] If the wireless communication terminal that receives the DL MU PPDU does not receive information on the UL MU transmission, the wireless communication terminal may not be able to send an ACK for the MPDU including information on the operation mode change even if the wireless communication terminal receives information on the operation mode change. In this case, the base wireless communication terminal may not be able to quickly change the operation mode. In Figure 12 In the embodiment of (c), the base wireless communication terminal transmits an A-MPDU including a plurality of MPDUs including ROMI to the first station STA1 and the second station STA2. In this case, the second station STA2 receives all the MPDUs transmitted by the base wireless communication terminal and transmits a block ACK frame for the received MPDUs. The first station STA1 does not receive the MPDU including the UL MU response information. Accordingly, even if the first station STA1 receives ROMI from the base wireless communication terminal, the first station STA1 cannot send an ACK for the MPDU including ROMI. Accordingly, the base wireless communication terminal only changes the receiver operation mode of the first station STA1 and cannot change the receiver operation mode of the second station STA2.

[0120] Accordingly, when the base wireless communication terminal transmits information on the operation mode change through the MPDU included in the DL MU PPDU, the base wireless communication terminal may insert the information on the operation mode change into the broadcast MPDU. In this case, the broadcast MPDU is an MPDU received by all the wireless communication terminals that receive the DL MU PPDU.

[0121] The wireless communication terminal may transmit information on the operation mode change through the MPDU included in the UL MU PPDU. Specifically, the wireless communication terminal may transmit information on the operation mode change through the MPDU included in the trigger-based PPDU. In Figure 12In the embodiment of (b), the first station STA1 and the second station STA2 send the ROMI to the basic wireless communication terminal through the MPDUs included in the UL MU PPDU. The basic wireless communication terminal receives all the MPDUs sent by the first station STA1. The basic wireless communication terminal does not receive the MPDU including the ROMI among the multiple MPDUs sent by the second station STA2. Therefore, the basic wireless communication terminal sends a block ACK frame indicating that all the MPDUs sent by the first station STA1 and the MPDUs sent by the second station STA2 that do not include the ROMI are received. The first station STA1 receives the block ACK frame from the basic wireless communication terminal and changes the receiver operation mode of the basic wireless communication terminal.

[0122] As in the embodiments described in reference Figure 12 (a) to Figure 12 (d), the wireless communication terminal may request immediate ACK transmission of the MPDU including information about the operation mode change. In addition, the wireless communication terminal may send the MPDU including information about the operation mode change through the SU PPDU. In addition, the wireless communication terminal may send the MPDU including information about the operation mode change through the trigger-based PPDU.

[0123] Figure 13 Shows the operation of sending a UL MU PPDU during the MU cascade transmission according to an embodiment of the present invention.

[0124] When the wireless communication terminal sends a UL MU PPDU based on the UL MU response information, the UL MU PPDU can be sent under the following conditions. Specifically, when the wireless communication terminal sends an A-MPDU including an ACKMPDU and a data MPDU through the UL MU PPDU based on the UL MU response information, the UL MU PPDU can be sent under the following conditions.

[0125] When a wireless communication terminal transmits a UL MU PPDU based on UL MU response information, the wireless communication terminal may transmit the UL MU PPDU without carrier sensing. In a specific embodiment, when the wireless communication terminal transmits a UL MU PPDU, the requirement for carrier sensing of the wireless communication terminal may be determined according to the length of the uplink transmission duration. Therefore, when the wireless communication terminal transmits a UL MU PPDU based on UL MU response information, the wireless communication terminal may perform carrier sensing based on the length of the uplink transmission duration. For example, when the wireless communication terminal transmits a UL MU PPDU based on UL MU response information, if the length of the uplink transmission duration is greater than a specified value, carrier sensing of the wireless communication terminal may be required. In this case, when the channel is idle, the wireless communication terminal may be able to start the transmission of the UL MU PPDU. The uplink transmission duration may be the duration indicated by the UL PPDU length field of the above UL MU response information.

[0126] When a wireless communication terminal transmits a UL MU PPDU based on UL MU response information, the wireless communication terminal may not allow spatial reuse (SR) transmission of the UL MU PPDU. Specifically, when the wireless communication terminal transmits a UL MU PPDU, signaling information indicating whether SR transmission is allowed may be set so that SR transmission is not allowed. In a specific embodiment, when the wireless communication terminal transmits a UL MU PPDU, the wireless communication terminal may set the SR parameter of the transmission parameter TXVECTOR to a value indicating that SR transmission is not allowed. In another specific embodiment, when the wireless communication terminal transmits a UL MU PPDU based on UL MU response information, the wireless communication terminal may set whether SR transmission is allowed according to an indication from the basic wireless communication terminal.

[0127] In addition, when a wireless communication terminal transmits a UL MU PPDU based on UL MU response information, the wireless communication terminal may use a frequency bandwidth of the same size as the frequency bandwidth of the DL MU PPDU including the UL MU response information as the BW value of the transmission parameter TXVECTOR. In this case, the BW value may indicate the BW field value of the HE-SIG-A field of the UL MU PPDU.

[0128] In addition, when a wireless communication terminal transmits a UL MU PPDU based on UL MU response information, the wireless communication terminal may use the default CP / LTF type of the UL MU PPDU.

[0129] In addition, when the wireless communication terminal transmits a UL MU PPDU based on UL MU response information, the wireless communication terminal may not use MU-MIMO. In addition, when the wireless communication terminal transmits a UL MU PPDU based on UL MU response information, the wireless communication terminal may not use the MU-MIMO LTF mode. Specifically, when the wireless communication terminal transmits a UL MU PPDU, the wireless communication terminal may set the SS allocation parameter of the transmission parameter TXVECTOR to 0. In addition, when the wireless communication terminal transmits a UL MU PPDU, the wireless communication terminal may set the number of spatial streams of the transmission parameter TXVECTOR to 0.

[0130] In addition, when the wireless communication terminal transmits a UL MU PPDU based on UL MU response information, the wireless communication terminal may use a binary convolutional coding (BCC) code to transmit the UL MU PPDU. Specifically, when the wireless communication terminal transmits a UL MU PPDU, the wireless communication terminal may set the coding type parameter of the transmission parameter TXVECTOR to 0. In addition, when the wireless communication terminal transmits a UL MU PPDU, the wireless communication terminal may set the LDPC additional parameter of the transmission parameter TXVECTOR to 0.

[0131] In addition, when the wireless communication terminal transmits a UL MU PPDU based on UL MU response information, the wireless communication terminal may not use STBC to transmit the UL MU PPDU. Specifically, when the wireless communication terminal transmits a UL MU PPDU, the wireless communication terminal may set the STBC parameter of the transmission parameter TXVECTOR to 0.

[0132] In addition, when the wireless communication terminal transmits a UL MU PPDU based on UL MU response information, even if the UL MU response information is transmitted separately for each A-MPDU in the DL MUPPDU, the wireless communication terminal may not arbitrarily extend the number of symbols used to transmit the LTF. Specifically, the wireless communication terminal may transmit the LTF through one symbol. In a specific embodiment, when the wireless communication terminal transmits a UL MU PPDU, the wireless communication terminal may set the number of LTF parameters of the transmission parameter TXVECTOR to 1.

[0133] In addition, when the wireless communication terminal transmits a UL MU PPDU based on UL MU response information, the wireless communication terminal may not perform power control based on the AP TX power / target RSSI information.

[0134] In addition, when the wireless communication terminal transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal may transmit the UL MU PPDU by setting the packet extension field according to the method specified by the basic wireless communication terminal. Specifically, when the wireless communication terminal transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal may set the length of the packet extension field to the length specified by the basic wireless communication terminal to transmit the UL MU PPDU.

[0135] In addition, when the wireless communication terminal transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal may select the MCS to be used in the transmission of the UL MU PPDU according to the ACK rate selection method of the MCS of the received data MPDU.

[0136] In addition, when the wireless communication terminal transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal may transmit the UL MU PPDU without using DCM.

[0137] The wireless communication terminal may use the UL MU response information through these embodiments to improve the efficiency of MU cascade transmission. In addition, when the wireless communication terminal transmits a UL MU PPDU based on the UL MU response information through these embodiments, the problem that the UL MU PPDU transmission operation becomes unclear due to the format difference between the trigger frame and the UL MU response information can be solved.

[0138] When the basic wireless communication terminal triggers the uplink transmission of multiple wireless communication terminals through a DL MU PPDU, the basic wireless communication terminal may transmit only one of the trigger MPDU and the UL MU response information for each of the multiple wireless communication terminals. Therefore, the A-MPDU may not simultaneously include the UL MU response information and the trigger MPDU that triggers the same wireless communication terminal as the wireless communication terminal indicated by the UL MU response information. Specifically, as in the embodiment of Figure 13 (a), the basic wireless communication terminal may transmit a DL MU PPDU including a trigger MPDU and a UL MU response information to the first station STA1 to the third station STA3. In this case, the basic wireless communication terminal may transmit the trigger MPDU to the first station STA1, transmit the UL MU response information to the second station STA2, and transmit the trigger MPDU to the third station STA3. Through these embodiments, the basic wireless communication terminal may reduce the complexity of configuring the trigger MPDU and the UL MU response information.

[0139] In Figure 13In the embodiment of (a), the third station STA3 only receives data MPDUs from the basic wireless communication terminal and does not receive trigger MPDUs. Therefore, the third station STA3 may not send a UL MU PPDU to the basic wireless communication terminal. When the basic wireless communication terminal triggers uplink transmissions of multiple wireless communication terminals via a DL MU PPDU, the basic wireless communication terminal may send both a trigger MPDU and UL MU response information for each of the multiple wireless communication terminals. In this case, the UL MU response information and the information indicated by the trigger MPDU should be the same or similar. In Figure 13 In the embodiment of (b), the third station STA3 does not receive a trigger MPDU but receives UL MU response information. Therefore, the third station STA sends a UL MU PPDU to the basic wireless communication terminal.

[0140] Figure 14 Illustrates the operation of a wireless communication terminal according to an embodiment of the present invention.

[0141] The basic wireless communication terminal 1401 sends a DL MU PPDU including information for UL MU transmission to a plurality of wireless communication terminals including the wireless communication terminal 1403 (S1401). The UL MU transmission information may be the above-mentioned UL MU response information. Additionally, the information for UL MU transmission may be the above-mentioned trigger MPDU. In this case, the UL MU response information may be information included in the MAC header. Specifically, the UL MU response information may be information for scheduling a trigger-based PPDU including an ACK. Additionally, the trigger-based PPDU may be a UL MU PPDU.

[0142] In addition, the basic wireless communication terminal 1401 may send an A-MPDU via a DL MU PPDU. In this case, the basic wireless communication terminal 1401 may send at least one of a control MPDU and a management MPDU together with a data MPDU, as described above. The basic wireless communication terminal 1401 may send an A-MPDU including a block ACK MPDU, a BAR MPDU, and a data MPDU. When the basic wireless communication terminal 1401 sends an A-MPDU including a block ACK MPDU, a BAR MPDU, and a data MPDU, the basic wireless communication terminal 1401 may send the block ACK MPDU as the first MPDU of the A-MPDU. In addition, when the basic wireless communication terminal 1401 sends an A-MPDU including a block ACK MPDU, a BAR MPDU, and a data MPDU, the basic wireless communication terminal 1401 may send the BAR MPDU as the last MPDU of the A-MPDU. Specifically, when the basic wireless communication terminal 1401 sends an A-MPDU including a block ACK MPDU, a BAR MPDU, and a data MPDU, the basic wireless communication terminal 1401 may send the block ACK MPDU as the first MPDU of the A-MPDU and the BAR MPDU as the last MPDU of the A-MPDU. Specifically, the basic wireless communication terminal 1401 may send the A-MPDU as in the embodiment described in reference Figure 10 and send the A-MPDU as in the described embodiment.

[0143] In addition, the basic wireless communication terminal 1401 may send only one of a trigger MPDU and UL MU response information to the wireless communication terminal 1403. Therefore, the A-MPDU sent to the wireless communication terminal 1403 may not simultaneously include UL MU response information for the wireless communication terminal 1403 and a trigger MPDU that triggers the wireless communication terminal 1403. In another specific embodiment, the basic wireless communication terminal 1401 may send both the trigger MPDU and the UL MU response information to the wireless communication terminal 1403.

[0144] The wireless communication terminal 1403 transmits a UL MU PPDU based on information for UL MU transmission (S1403). Specifically, the wireless communication terminal 1403 may obtain information for UL MU transmission from the DL MU PPDU, and transmit the UL MU PPDU based on the obtained information for UL MU transmission. In this case, the UL MU transmission information may be the ULMU response information as described above. When the wireless communication terminal 1403 transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal 1403 may transmit the UL MU PPDU without carrier sensing. In a specific embodiment, when the wireless communication terminal 1403 transmits a UL MU PPDU, the requirement for carrier sensing of the wireless communication terminal may be determined according to the length of the uplink transmission duration. Therefore, when the wireless communication terminal 1403 transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal 1403 may perform carrier sensing based on the length of the uplink transmission duration. For example, when the wireless communication terminal 1403 transmits a UL MU PPDU based on the UL MU response information, if the length of the uplink transmission duration is greater than a specified value, carrier sensing of the wireless communication terminal 1403 may be required. In this case, when the channel is idle, the wireless communication terminal 1403 may be able to start the transmission of the UL MU PPDU. The uplink transmission duration may be the duration indicated by the UL PPDU length field of the above UL MU response information.

[0145] When the wireless communication terminal 1403 transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal 1403 may not allow spatial reuse (SR) transmission for the UL MU PPDU. Specifically, when the wireless communication terminal 1403 transmits a UL MUPPDU, signaling information indicating whether SR transmission is allowed may be set such that SR transmission is not allowed. In a specific embodiment, when the wireless communication terminal 1403 transmits a UL MU PPDU, the wireless communication terminal may set the SR parameter of the transmission parameter TXVECTOR to a value indicating that SR transmission is not allowed.

[0146] In addition, when the wireless communication terminal 1403 transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal 1403 may use a frequency bandwidth of the same size as the frequency bandwidth of the DL MU PPDU including the UL MU response information as the BW value of the transmission parameter TXVECTOR. Specifically, when the wireless communication terminal 1403 transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal 1403 may use the same frequency band as the frequency band of the DL MU PPDU including the UL MU response information.

[0147] In addition, when the wireless communication terminal 1403 transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal 1403 may use the default CP / LTF type of the UL MU PPDU.

[0148] In addition, when the wireless communication terminal 1403 transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal 1403 may not use MU-MIMO. Therefore, when the wireless communication terminal 1403 transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal 1403 may not use the MU-MIMO LTF mode. Specifically, when the wireless communication terminal 1403 transmits a UL MU PPDU, the wireless communication terminal 1403 may set the SS allocation parameter of the transmission parameter TXVECTOR to 0.

[0149] In addition, when the wireless communication terminal 1403 transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal 1403 may use a binary convolutional coding (BCC) code to transmit the UL MU PPDU. Specifically, when the wireless communication terminal 1403 transmits a UL MU PPDU, the wireless communication terminal may set the coding type parameter of the transmission parameter TXVECTOR to 0. In addition, when the wireless communication terminal 1403 transmits a UL MU PPDU, the wireless communication terminal may set the LDPC additional parameter of the transmission parameter TXVECTOR to 0.

[0150] In addition, when the wireless communication terminal 1403 transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal 1403 may transmit the UL MU PPDU without using STBC. Specifically, when the wireless communication terminal 1403 transmits a UL MU PPDU, the wireless communication terminal 1403 may set the STBC parameter of the transmission parameter TXVECTOR to 0.

[0151] In addition, when the wireless communication terminal 1403 transmits a UL MU PPDU based on the UL MU response information, even if the UL MU response information is transmitted individually for each A-MPDU in the DL MU PPDU, the wireless communication terminal 1403 may not arbitrarily extend the number of symbols used to transmit the LTF. Specifically, the wireless communication terminal 1403 may transmit the LTF through one symbol. In a specific embodiment, when the wireless communication terminal transmits a UL MU PPDU, the wireless communication terminal may set the number of LTF parameters of the transmission parameter TXVECTOR to 1.

[0152] In addition, when the wireless communication terminal 1403 transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal 1403 may not perform power control based on the AP TX power / target RSSI information.

[0153] In addition, when the wireless communication terminal 1403 transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal 1403 may not perform power control based on the AP TX power / target RSSI information.

[0154] In addition, when the wireless communication terminal 1403 transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal 1403 may set a packet extension field according to the method specified by the basic wireless communication terminal 1401 to transmit the UL MU PPDU. Specifically, when the wireless communication terminal 1403 transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal 1403 may set the length of the packet extension field to the length specified by the basic wireless communication terminal 1401 to transmit the UL MU PPDU. In addition, when the wireless communication terminal 1403 transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal 1403 may select the MCS to be used in the transmission of the UL MU PPDU according to the ACK rate selection method based on the MCS of the received data MPDU.

[0155] In addition, when the wireless communication terminal 1403 transmits a UL MU PPDU based on the UL MU response information, the wireless communication terminal 1403 may transmit the UL MU PPDU without using the DCM.

[0156] As described above, when transmitting the DL MU PPDU, the basic wireless communication terminal 1401 may request the wireless communication terminal 1403 to transmit an ACK and specify the format of the ACK. The basic wireless communication terminal 1401 may request the wireless communication terminal 1403 to transmit an ACK and specify the format of the ACK through the Ack policy field in the QoS control field of the MAC header. Specifically, the basic wireless communication terminal 1401 may request the wireless communication terminal 1403 to perform ACK transmission and specify the ACK format, as Figure 8 in the embodiment of.

[0157] In addition, the basic wireless communication terminal 1401 may send a BAR frame to the wireless communication terminal 1403 to request an immediate transmission of a block ACK frame. In addition, the basic wireless communication terminal 1401 may send a MU-BAR frame to the wireless communication terminal 1403 to request an immediate transmission of a MU block ACK frame.

[0158] In MU cascade transmission, the base wireless communication terminal may request the wireless communication terminal 1403 to send an immediate MU block ACK frame for data transmission. Specifically, the base wireless communication terminal may request the immediate transmission of the MU block ACK for data transmission from the wireless communication terminal 1403 through the Ack policy field of the MU-BAR frame or the QoS control field.

[0159] When the base wireless communication terminal 1401 requests the wireless communication terminal 1403 to immediately send an MU block ACK frame but does not receive the MU block ACK frame, the base wireless communication terminal 1401 may send an MU-BAR frame to the wireless communication terminal 1403. Specifically, when the base wireless communication terminal 1401 requests the transmission of the MU block ACK frame by setting the acknowledgment policy field of the HT control field to 1 (01b) but fails to receive the MU block ACK, the base wireless communication terminal 1401 may send the MU-BAR frame to the wireless communication terminal 1403. In a particular embodiment, if the base wireless communication terminal 1401 sends the UL MU response information for sending the MU block ACK to the wireless communication terminal 1403 and requests the transmission of the MU block ACK frame by setting the acknowledgment policy field of the HT control field to 1 (01b), but fails to receive the MU block ACK frame, then the base wireless communication terminal 1401 may send the MU-BAR frame to the wireless communication terminal 1403. Additionally, if the base wireless communication terminal 1401 sends the MU-BAR MPDU for sending the MU block ACK to the wireless communication terminal 1403, requests the transmission of the MU-block ACK frame by setting the Ack policy field of the HT control field to 1 (01b), but fails to receive the MU-block ACK frame, the base wireless communication terminal 1401 may send the MU-BAR frame to one or more wireless communication terminals. Specifically, the base wireless communication terminal 1401 may operate as in the embodiments described in the reference Figure 9 as described.

[0160] In addition, the base wireless communication terminal 1401 and the wireless communication terminal 1403 may request the immediate ACK transmission for an MPDU including information about a change in the operation mode. In addition, the base wireless communication terminal 1401 and the wireless communication terminal 1403 may send an MPDU including information about a change in the operation mode through an SU PPDU. In addition, the base wireless communication terminal 1401 and the wireless communication terminal 1403 may send an MPDU including information about a change in the operation mode through a trigger-based PPDU.

[0161] Although the present invention has been described by using wireless LAN communication as an example, the present invention is not limited thereto and can be applied to other communication systems such as cellular communication. Additionally, although the methods, devices, and systems of the present invention are described in conjunction with specific embodiments of the present invention, some or all of the components or operations of the present invention can be implemented using a computer system having a general hardware architecture.

[0162] The features, structures, and effects described in the above embodiments are included in at least one embodiment of the present invention and are not necessarily limited to one embodiment. Additionally, those skilled in the art can combine or modify the features, structures, and effects shown in each embodiment in other embodiments. Therefore, it should be understood that the content related to such combinations and modifications is included within the scope of the present invention.

[0163] Although the present invention is mainly described based on the above embodiments but is not limited thereto, those skilled in the art will understand that various changes and modifications can be made without departing from the spirit and scope of the present invention. For example, each component specifically shown in the embodiments can be modified and implemented. It should be understood that the differences related to such modifications and applications are included within the scope of the present invention defined in the appended claims.

Claims

1. A wireless communication terminal for wireless communication, the wireless communication terminal comprising: a transceiver; and a processor, wherein the processor is configured to: receive, by using the transceiver, a downlink multi-user (DL MU) physical layer protocol data unit (PPDU) including information for uplink multi-user (UL MU) transmission from a base wireless communication terminal, when the information for the UL MU transmission is a trigger MAC protocol data unit (MPDU), determine whether carrier sensing is required according to the CS required field of the common information field of the trigger MPDU, and based on the information for the UL MU transmission and the determination, send a PPDU for the UL MU transmission to the base wireless communication terminal, and when the information for the UL MU transmission is UL MU response information, send, without carrier sensing, the PPDU for the UL MU transmission to the base wireless communication terminal by using the transceiver based on the information for the UL MU transmission, wherein the UL MU response information includes transmission scheduling information for the PPDU for the UL MU transmission and is included in a media access control (MAC) header.

2. The wireless communication terminal according to claim 1, when the information for the UL MU transmission is the UL MU response information, wherein, The processor is configured to set a BW value of a transmission parameter (TXVECTOR) of the PPDU for the UL MU transmission to a frequency bandwidth of the DL MU PPDU.

3. The wireless communication terminal according to claim 1, when the information for the UL MU transmission is UL MU response information, wherein, The processor is configured to send the PPDU for the UL MU transmission without using UL MU multiple-input multiple-output (MIMO).

4. The wireless communication terminal according to claim 1, when the information for the UL MU transmission is the UL MU response information, wherein, The processor is configured to use a binary convolutional coding (BCC) code to send the PPDU for the UL MU transmission.

5. The wireless communication terminal according to claim 1, when the information for the UL MU transmission is UL MU response information, wherein, The processor is configured to set a length of a packet extension field of the PPDU for the UL MU transmission according to a length indicated by the base wireless communication terminal.

6. The wireless communication terminal according to claim 1, wherein, When the information for the UL MU transmission is the UL MU response information, an aggregated MAC protocol data unit (A-MPDU) including the UL MU response information does not include a trigger MPDU, and the trigger MPDU triggers the wireless communication terminal triggered by the UL MU response information.

7. The wireless communication terminal according to claim 1, when the information for the UL MU transmission is the trigger MPDU for triggering the UL MU transmission of the wireless communication terminal, wherein, An aggregated MPDU (A-MPDU) including the trigger MPDU includes a block ACK MPDU as a first MPDU and includes the trigger MPDU as a second MPDU.

8. The wireless communication terminal according to claim 7, wherein, When the information for the UL MU transmission is the trigger MPDU for triggering the UL MU transmission of the wireless communication terminal, the A-MPDU includes a block ACK request (BAR) MPDU as a last MPDU.

9. A method of operating a wireless communication terminal for wireless communication, the method comprising: receiving, from a base wireless communication terminal, a downlink multi-user (DL MU) physical layer protocol data unit (PPDU) including information for uplink multi-user (UL MU) transmission, When the information for the UL MU transmission is a triggered MAC protocol data unit (MPDU), determine whether carrier sensing is required according to the CS required field in the common information field of the triggered MPDU, and based on the information for the UL MU transmission and the determination, send a PPDU for the UL MU transmission to the basic wireless communication terminal, and When the information for the UL MU transmission is UL MU response information, send the PPDU for the UL MU transmission to the basic wireless communication terminal based on the information for the UL MU transmission without the carrier sensing, wherein the UL MU response information includes transmission scheduling information of the PPDU for the UL MU transmission and is included in a media access control (MAC) header.

10. The method according to claim 9, when the information for the UL MU transmission is the UL MU response information, wherein, Sending the PPDU for the UL MU transmission includes: using a frequency bandwidth of the same size as the frequency bandwidth of the DL MU PPDU as the BW value of a transmission parameter (TXVECTOR) of the PPDU for the UL MU transmission.

11. According to the method of claim 9, when the information for the UL MU transmission is UL MU response information, wherein, Sending the PPDU for the UL MU transmission includes: sending the PPDU for the UL MU transmission without using UL MU multiple-input multiple-output (MIMO).

12. According to the method of claim 9, when the information for the UL MU transmission is the UL MU response information, wherein, Sending the PPDU for the UL MU transmission includes: using a binary convolutional coding (BCC) code to send the PPDU for the UL MU transmission.

13. According to the method of claim 9, when the information for the UL MU transmission is the UL MU response information, wherein, Sending the PPDU for the UL MU transmission includes: setting a packet extension field of the PPDU for the UL MU transmission according to a length indicated by the basic wireless communication terminal.

14. The method according to claim 9, when the information for the UL MU transmission is the UL MU response information, wherein, An aggregated MAC protocol data unit (A-MPDU) including the UL MU response information does not include a triggered MPDU that triggers a wireless communication terminal triggered by the UL MU response information.

15. The method according to claim 9, when the information for the UL MU transmission is a triggered MPDU, wherein, An aggregated MPDU (A-MPDU) including the triggered MPDU includes a block ACK MPDU as a first MPDU and includes the triggered MPDU as a second MPDU.

16. The method according to claim 15, wherein When the information for the UL MU transmission is the triggered MPDU, the A-MPDU includes a block ACK request (BAR) MPDU as a last MPDU.

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