Method for transmitting aggregate MPDU and corresponding response frame, and wireless communication terminal using the same

Abstract

The present invention relates to a method for transmitting an aggregate MPDU and a response frame thereto, and a wireless communication terminal using the same, and more particularly to a wireless communication method and a wireless communication terminal for setting various formats of an aggregate MPDU and a response frame thereto and using the same to perform efficient data communication. [Solution] To this end, the present invention provides a wireless communication terminal including a processor and a communication unit as a wireless communication terminal, in which the processor generates an aggregate MPDU (A-MPDU) including one or more MPDUs (MAC Protocol Data Units) requesting an immediate response, transmits the generated A-MPDU to a receiver, receives a response frame from the receiver corresponding to the A-MPDU, and determines whether the transmission of the MPDU included in the A-MPDU was successful based on the received response frame, and a wireless communication method using the same.

Description

[Technical field]

[0001] The present invention relates to a method for transmitting an aggregate MPDU and a response frame thereto, and a wireless communication terminal using the same, and more particularly to a wireless communication method and a wireless communication terminal for setting various formats of an aggregate MPDU and a response frame thereto and performing efficient data communication using the same. [Background technology]

[0002] Recently, as the use of mobile devices has become more widespread, wireless LAN technology that can provide them with high-speed wireless Internet services has been attracting attention. Wireless LAN technology is a technology that enables mobile devices such as smartphones, smart pads, laptop PCs, portable multimedia players, embedded devices, etc. to wirelessly connect to the Internet at home, in business, or in specific service areas based on short-distance wireless communication technology.

[0003] Since IEEE (Institute of Electronics Engineers) 802.11 supported early wireless LAN technology using 2.4GHz frequency, it has put into practical use or is currently developing standards for various technologies. First, IEEE 802.11b uses the 2.4GHz frequency band and supports a maximum communication speed of 11Mbps. IEEE 802.11a, which was commercialized after IEEE 802.11b, uses the 5GHz frequency band instead of the 2.4GHz band, reducing the impact of interference compared to the significantly more congested 2.4GHz frequency band, and uses OFDM technology to increase communication speeds to a maximum of 54Mbps. However, IEEE 802.11a has the disadvantage of a shorter communication distance than IEEE 802.11b. IEEE 802.11g, like IEEE 802.11b, uses the 2.4GHz frequency band to achieve a maximum communication speed of 54Mbps and satisfies backward compatibility, which has attracted considerable attention, but it also has an advantage over IEEE 802.11a in communication distance.

[0004] IEEE 802.11n is a technical standard established to overcome the communication speed limitations that have been pointed out as a weakness of wireless LAN. The purpose of IEEE 802.11n is to increase the speed and reliability of the network and to extend the operating distance of the wireless network. In detail, IEEE 802.11n supports a high throughput (HT) of up to 540Mbps or more in data processing speed, and is based on MIMO (Multiple Inputs and Multiple Outputs) technology that uses multiple antennas on both the transmitting and receiving ends to minimize transmission errors and optimize data speed. This standard also uses a coding method that transmits multiple duplicate copies to increase data reliability.

[0005] As the use of wireless LANs becomes more widespread and applications using them become more diverse, the need for new wireless LAN systems to support data throughput rates (Very High Throughput, VHT) higher than those supported by IEEE 802.11n is emerging. Among them, IEEE 802.11ac supports wide bandwidth (80MHz~160MHz) at 5GHz frequency. Although the IEEE 802.11ac standard is defined only in the 5GHz band, it is expected that initial 11ac chipsets will also support operation in the 2.4GHz band for backward compatibility with existing 2.4GHz band products. Theoretically, this standard allows multi-station wireless LAN speeds of at least 1Gbps and maximum single link speeds of at least 500Mbps. This is done by extending the air interface concepts accepted by 802.11n, such as wider radio frequency bandwidth (up to 160MHz), more MIMO spatial streams (up to 8), multi-user MIMO, and high density modulation (up to 256QAM). Also, there is IEEE 802.11ad, a method of transmitting data using the 60GHz band instead of the conventional 24GHz / 5GHz. IEEE 802.11ad is a transmission standard that uses beamforming technology to provide speeds of up to 7Gbps, and is suitable for streaming large amounts of data and high bitrate videos such as uncompressed HD video. However, the 60GHz frequency band has the disadvantage that it is difficult to pass through obstacles and can only be used between devices in close proximity.

[0006] Meanwhile, discussions are currently ongoing to provide high-efficiency and high-performance wireless LAN communication technology in high-density environments as the standard for next-generation wireless LANs after 802.11ac and 802.11ad. In other words, next-generation wireless LAN environments should provide high-frequency-efficient communication both indoors and outdoors in the presence of high-density stations and APs (Access Points), and various technologies are required to realize this. Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, the present invention has an object to provide highly efficient / high performance wireless LAN communication in a high density environment.

[0008] The present invention has an object to set various formats of aggregate MPDUs and response frames thereto, and to use them to perform efficient data communication. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, the present invention provides a wireless communication terminal and a wireless communication method for a terminal as follows.

[0010] First, according to one embodiment of the present invention, a wireless communication terminal is provided, which includes a processor and a communication unit, wherein the processor generates an aggregate MPDU (A-MPDU) including one or more MPDUs (MAC Protocol Data Units) requesting an immediate response, transmits the generated A-MPDU to a receiver, receives a response frame from the receiver corresponding to the A-MPDU, and determines whether the transmission of the MPDU included in the A-MPDU was successful based on the received response frame.

[0011] The processor determines whether the MPDU included in the A-MPDU was successfully transmitted by considering at least one of the number of TIDs (Traffic IDs) and MPDU classification information requesting an immediate response among one or more MPDUs constituting the A-MPDU, and the response frame transmitted in response to the A-MPDU.

[0012] If the A-MPDU is composed of MPDUs of multiple TIDs requesting an immediate response and the response frame transmitted in response to the A-MPDU is an Ack frame, the processor determines that transmission of the MPDU included in the A-MPDU has failed.

[0013] The processor retransmits the MPDU included in the A-MPDU determined to have been unsuccessfully transmitted.

[0014] The processor determines that channel access for the A-MPDU transmission is successful and resets at least one EDCA parameter of an access category used for the channel access.

[0015] The response frame of the A-MPDU is generated based on at least one of the number of TIDs for which an immediate response is requested among the MPDUs of the A-MPDU successfully received by the receiver and the MPDU segmentation information of the A-MPDU.

[0016] If the MPDU successfully received by the receiver contains only one MPDU requesting an immediate response and the MPDU requesting an immediate response is followed by an MPDU separator whose EOF (End of Frame) field value is 1 and whose MPDU length field value is not 0, the response frame of the A-MPDU is an Ack frame.

[0017] If the MPDU successfully received by the receiver includes one or more MPDUs of only one TID requesting an immediate response, and the MPDU requesting an immediate response is preceded by an MPDU separator whose EOF field value is 0, then the response frame of the A-MPDU is a compressed BlockAck frame.

[0018] If the MPDU successfully received by the receiver includes MPDUs for multiple TIDs requesting an immediate response, or includes MPDUs for one or more TIDs requesting an immediate response and an action frame, the response frame for the A-MPDU is a multi-STA BlockAck frame.

[0019] If at least one MPDU or MPDU fragment in the A-MPDU is not successfully received by the recipient, the response frame of the A-MPDU is a multi-STA BlockAck frame.

[0020] If at least one MPDU or MPDU fragment is not successfully received by the recipient prior to the first received EOF padding in the A-MPDU, the response frame of the A-MPDU is a multi-STA BlockAck frame.

[0021] The receiver responds to the A-MPDU with the Multi-STA BlockAck frame if the Multi-STA BlockAck frame can be transmitted within the duration indicated by the successfully received MPDU or within the length indicated by the trigger information received in the A-MPDU.

[0022] In addition, according to one embodiment of the present invention, a wireless communication method for a wireless communication terminal is provided, comprising the steps of generating an aggregate MPDU (A-MPDU) including one or more MPDUs requesting an immediate response, transmitting the generated A-MPDU to a receiver, receiving a response frame from the receiver corresponding to the A-MPDU, and determining whether the transmission of the MPDU included in the A-MPDU was successful based on the received response frame.

[0023] Next, according to another embodiment of the present invention, a wireless communication terminal includes a processor and a communication unit, and the processor receives an aggregate MPDU (A-MPDU) composed of one or more MPDUs, determines a format of a response frame for the received A-MPDU, and transmits the response frame in the determined format.

[0024] The format of the response frame for the A-MPDU is determined based on at least one of the number of TIDs requesting an immediate response among the MPDUs successfully received in the A-MPDU and the MPDU segmentation information of the A-MPDU.

[0025] If the successfully received MPDU contains only one MPDU requesting an immediate response, and the MPDU requesting an immediate response has an EOF field value of 1 and an MPDU length field value other than 0 that follows the MPDU byte, the response frame of the A-MPDU is determined to be an Ack frame.

[0026] If the successfully received MPDU includes one or more MPDUs of only one TID requesting an immediate response, and the MPDU requesting an immediate response is followed by an MPDU segment whose EOF field value is 0, the response frame of the A-MPDU is determined to be a compressed BlockAck frame.

[0027] If the successfully received MPDU includes MPDUs of multiple TIDs requesting an immediate response, or includes an MPDU of one or more TIDs requesting an immediate response and an action frame, the response frame of the A-MPDU is determined to be a multi-STA BlockAck frame.

[0028] If at least one MPDU or MPDU fragment in the A-MPDU is not successfully received by the recipient, the response frame of the A-MPDU is a multi-STA BlockAck frame.

[0029] If at least one MPDU or MPDU fragment is not successfully received before the first received EOF padding in the A-MPDU, the response frame of the A-MPDU is determined to be a multi-STA BlockAck frame.

[0030] If the multi-STA Block Ack frame can be transmitted within the duration indicated by the MPDU successfully received in the A-MPDU or within the length indicated by the trigger information received in the A-MPDU, the response frame of the A-MPDU is determined to be the multi-STA Block Ack frame.

[0031] If the successfully received MPDU includes only one MPDU requesting an immediate response and a trigger frame, and the MPDU requesting an immediate response is followed by an MPDU segment whose EOF field value is 1 and whose MPDU length field value is not 0, the response frame of the A-MPDU is determined to be an Ack frame.

[0032] According to another embodiment of the present invention, there is provided a wireless communication method for a wireless communication terminal, the wireless communication method including the steps of receiving an aggregate MPDU (A-MPDU) composed of one or more MPDUs, determining a format of a response frame for the received A-MPDU, and transmitting the response frame in the determined format. Effect of the Invention

[0033] According to the embodiment of the present invention, it is possible to set aggregate MPDUs of various formats and response frames corresponding thereto, thereby enabling efficient data communication.

[0034] According to an embodiment of the present invention, in a contention-based channel access system, it is possible to increase the overall resource utilization rate and improve the performance of a wireless LAN system. [Brief description of the drawings]

[0035] [Figure 1] FIG. 1 is a diagram showing a wireless LAN system according to an embodiment of the present invention. [Diagram 2] FIG. 11 is a diagram showing a wireless LAN system according to another embodiment of the present invention. [Diagram 3] FIG. 2 is a diagram showing a configuration of a station according to an embodiment of the present invention. [Figure 4] FIG. 2 is a diagram showing the configuration of an access point according to an embodiment of the present invention. [Diagram 5] 1 is a diagram illustrating a process in which a STA sets up a link with an AP. [Figure 6(a)] FIG. 1 is a diagram showing an embodiment of a method for assembling MPDUs of a wireless LAN packet. [Figure 6(b)] FIG. 1 is a diagram showing an embodiment of a method for assembling MPDUs of a wireless LAN packet. [Figure 7(a)] FIG. 1 is a diagram showing an embodiment of a method for assembling MPDUs of wireless LAN packets in a non-legacy wireless LAN system. [Figure 7(b)] FIG. 1 is a diagram showing an embodiment of a method for assembling MPDUs of wireless LAN packets in a non-legacy wireless LAN system. [Figure 7(c)] FIG. 1 is a diagram showing an embodiment of a method for assembling MPDUs of wireless LAN packets in a non-legacy wireless LAN system. [Figure 8] A diagram showing another embodiment of an MPDU aggregation method for a WLAN packet in a non-legacy WLAN system. [Figure 9(a)] A diagram showing yet another embodiment of a method for assembling MPDUs of a WLAN packet in a non-legacy WLAN system. [Figure 9(b)] A diagram showing yet another embodiment of a method for assembling MPDUs of a WLAN packet in a non-legacy WLAN system. [Figure 10(a)] A figure showing one embodiment of a response method using the A-MPDU format. [Figure 10(b)] A figure showing one embodiment of a response method using the A-MPDU format. [Figure 10(c)] A figure showing one embodiment of a response method using the A-MPDU format. [Figure 11(a)] A diagram showing an embodiment of a method for a terminal to transmit a response frame for an A-MPDU. [Figure 11(b)] A diagram showing an embodiment of a method for a terminal to transmit a response frame for an A-MPDU. [Figure 11(c)] A diagram showing an embodiment of a method for a terminal to transmit a response frame for an A-MPDU. [Figure 12(a)] 13 is a diagram illustrating another embodiment of a method for a terminal to transmit a response frame for an A-MPDU. [Figure 12(b)]13 is a diagram illustrating another embodiment of a method for a terminal to transmit a response frame for an A-MPDU. [Figure 12(c)] 13 is a diagram illustrating another embodiment of a method for a terminal to transmit a response frame for an A-MPDU. [Figure 13(a)] A diagram showing one embodiment of a method for an AP to transmit a response frame to an A-MPDU. [Figure 13(b)] A diagram showing one embodiment of a method for an AP to transmit a response frame to an A-MPDU. [Figure 14(a)] A diagram showing a method of transmitting a response frame according to yet another embodiment of the present invention. [Figure 14(b)] A diagram showing a method of transmitting a response frame according to yet another embodiment of the present invention. [Figure 14(c)] A diagram showing a method of transmitting a response frame according to yet another embodiment of the present invention. [Figure 15(a)] A diagram showing a method for transmitting A-MPDU and a response frame according to one embodiment of the present invention. [Figure 15(b)] A diagram showing a method for transmitting A-MPDU and a response frame according to one embodiment of the present invention. [Figure 16(a)] A diagram showing a method for transmitting A-MPDU and a response frame according to another embodiment of the present invention. [Figure 16(b)] A diagram showing a method for transmitting A-MPDU and a response frame according to another embodiment of the present invention. [Figure 17] A diagram showing a method for transmitting A-MPDU and a response frame according to yet another embodiment of the present invention. [Figure 18(a)] A diagram showing a method of transmitting an S-MPDU and a response frame in a non-legacy wireless LAN system according to one embodiment of the present invention. [Figure 18(b)] A diagram showing a method of transmitting an S-MPDU and a response frame in a non-legacy wireless LAN system according to one embodiment of the present invention. [Figure 19(a)] A diagram showing a method of transmitting an S-MPDU and a response frame in a non-legacy wireless LAN system according to another embodiment of the present invention. [Figure 19(b)] A diagram showing a method of transmitting an S-MPDU and a response frame in a non-legacy wireless LAN system according to another embodiment of the present invention. [Figure 19(c)] A diagram showing a method of transmitting an S-MPDU and a response frame in a non-legacy wireless LAN system according to another embodiment of the present invention. [Figure 20] 13 is a diagram illustrating an operation of a wireless communication terminal transmitting an A-MPDU based on maximum number information of TIDs according to an embodiment of the present invention. [Figure 21] 13 is a diagram illustrating an operation of a wireless communication terminal transmitting an A-MPDU based on maximum number information of TIDs according to another embodiment of the present invention. [Figure 22] 13 is a diagram illustrating an operation of a wireless communication terminal transmitting an A-MPDU based on maximum number information of TIDs according to still another embodiment of the present invention. [Figure 23] 13 is a diagram illustrating an operation of a wireless communication terminal transmitting an A-MPDU based on maximum number information of TIDs according to still another embodiment of the present invention. [Figure 24] A diagram illustrating an operation of a wireless communication terminal setting maximum number information of TIDs of a trigger frame according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] The terms used in this specification are selected as general terms that are currently widely used as much as possible in consideration of the functions of the present invention, but this may vary depending on the intentions, customs, or the emergence of new technologies of the engineers in the relevant technical field. In addition, in certain cases, the applicant may arbitrarily select terms, and in such cases, the meanings of the terms will be described in the description of the relevant invention. Therefore, it is clear that the terms used in this specification should be interpreted not simply as terms, but based on the substantial meanings of the terms and the contents of this specification as a whole.

[0037] Throughout the specification, when a component is "connected" to another component, this includes not only when it is "directly connected" to another component, but also when it is "electrically connected" with another component in between. Furthermore, when a component "includes" a specific component, this means that it may further include the other component, not excluding the other component, unless otherwise specified to the contrary. In addition, limitations such as "greater than" or "less than" based on a specific critical value may be appropriately replaced with "more than" or "less than" depending on the embodiment.

[0038] This application claims priority based on Korean Patent Application Nos. 10-2016-0175999, 10-2017-0048145, and 10-2017-0146357, and the embodiments and descriptions described in each of the above applications which are the basis of priority are incorporated herein by reference in their entirety.

[0039] FIG 1 is a diagram showing a wireless LAN system according to an embodiment of the present invention. The wireless LAN system includes one or more Basic Service Sets (BSS), where a BSS is a set of devices that can successfully synchronize and communicate with each other. Generally, BSSs are classified into infrastructure BSSs and independent BSSs (IBSSs), and FIG 1 shows an infrastructure BSS.

[0040] As shown in FIG. 1, an infrastructure BSS (BSS1, BSS2) includes one or more stations (STA1, STA2, STA3, STA4, STA5), access points (PCP / AP-1, PCP / AP-2) which are stations providing distribution services, and a distribution system (DS) that connects multiple access points (PCP / AP-1, PCP / AP-2).

[0041] A station (STA) is any device including a medium access control (MAC) and a physical layer interface for a wireless medium according to the IEEE 802.11 standard, and in a broad sense includes not only non-AP stations but also APs. In this specification, the term "terminal" refers to either a non-AP or an AP, or both. A station for wireless communication includes a processor and a communication unit, and further includes a user interface unit and a display unit, etc., depending on the embodiment. The processor generates frames to be transmitted through a wireless network, processes frames received through the wireless network, and performs various other processes for controlling the station. The communication unit is functionally connected to the processor and transmits and receives frames through the wireless network for the station. In the present invention, the term "terminal" is used to include a user equipment (UE).

[0042] An access point (AP) is an entity that provides a connection to a distribution system DS via a wireless medium for a station associated therewith. In an infrastructure BSS, communication between non-AP stations is generally performed via the AP, but when a direct link is set up, direct communication is possible between non-AP stations. Meanwhile, in the present invention, AP is used as a concept including a personal BSS coordination point (PCP), but in a broad sense, AP includes all concepts such as a central controller, a base station (BS), a node B, a base transceiver system (BTS), or a site controller. In the present invention, AP is also referred to as a base wireless communication terminal, but in a broad sense, the base wireless communication terminal is used as a term including an AP, a base station, an eNodeB (eNB), and a transmission point TP. In addition, the base wireless communication terminal includes various types of wireless communication terminals that allocate communication medium resources and perform scheduling in communication with a plurality of wireless communication terminals.

[0043] A plurality of infrastructure BSSs are connected to each other via a distribution system DS. In this case, a plurality of BSSs connected to each other via the distribution system is called an Extended Service Set (ESS).

[0044] 2 is a diagram showing an independent BSS, which is a wireless LAN system according to another embodiment of the present invention, in which the same or corresponding parts in the embodiment of FIG. 2 are the same as or correspond to the embodiment of FIG.

[0045] BSS3 shown in Figure 2 is an independent BSS and does not include an AP, so all stations (STA6, STA7) are not connected to an AP. An independent BSS is not allowed to connect to a distribution system and forms a self-contained network. In an independent BSS, each station (STA6, STA7) is directly connected to each other.

[0046] 3 is a block diagram showing a configuration of a station 100 according to an embodiment of the present invention. As shown in the figure, the station 100 according to the embodiment of the present invention includes a processor 110, a communication unit 120, a user interface unit 140, a display unit 150, and a memory 160.

[0047] First, the communication unit 120 transmits and receives wireless signals such as wireless LAN packets, and is provided inside or outside the station 100. According to an embodiment, the communication unit 120 includes at least one communication module using different frequency bands. For example, the communication unit 120 includes communication modules using different frequency bands such as 2.4 GHz, 5 GHz, and 60 GHz. According to an embodiment, the station 100 includes a communication module using a frequency band of 6 GHz or more and a communication module using a frequency band of 6 GHz or less. Each communication module performs wireless communication with an AP or an external station according to the wireless LAN standard of the frequency band supported by the corresponding communication module. The communication unit 120 may operate only one communication module at a time or operate multiple communication modules simultaneously according to the performance and requirements of the station 100. When the station 100 includes multiple communication modules, each communication module may be provided in an independent form, or multiple modules may be integrated and provided on one chip. In an embodiment of the present invention, the communication unit 120 represents an RF (Radio Frequency) communication module that processes RF signals.

[0048] Next, the user interface 140 includes various types of input / output means provided in the station 100. That is, the user interface unit 140 receives user input using various input means, and the processor 110 controls the station 100 based on the received user input. Also, the user interface unit 140 performs output based on a command from the processor 110 using various output means.

[0049] Then, the display unit 150 outputs an image on a display screen. The display unit 150 outputs various display objects such as a user interface based on the contents performed by the processor 110 or a control command of the processor 110. The memory 160 also stores control programs used by the station 100 and various data associated therewith. Such control programs include connection programs required for the station 100 to connect to an AP or an external station.

[0050] The processor 110 of the present invention executes various commands or programs to process data within the station 100. The processor 110 also controls each unit of the station 100 and controls transmission and reception of data between the units. According to an embodiment of the present invention, the processor 110 executes a program for connection to an AP stored in the memory 160 and receives a communication setup message transmitted by the AP. The processor 110 also reads information on the priority conditions of the station 100 included in the communication setup message and requests a connection to the AP based on the information on the priority conditions of the station 100. The processor 110 of the present invention may refer to a main control unit of the station 100, or may refer to a control unit for individually controlling some components of the station 100, for example, the communication unit 120, depending on the embodiment. That is, the processor 110 may be a modem that modulates and demodulates a wireless signal transmitted and received from the communication unit 120, or a modulator and / or demodulator. The processor 110 controls various operations of transmitting and receiving wireless signals of the station 100 according to an embodiment of the present invention. A detailed embodiment of the present invention will be described later.

[0051] The station 100 shown in FIG. 3 is a block diagram according to an embodiment of the present invention, and the separate blocks are used to logically distinguish the elements of the device. Thus, the above-mentioned device elements may be mounted on one chip or multiple chips depending on the design of the device. For example, the processor 110 and the communication unit 120 may be integrated and embodied on one chip, or may be embodied on 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, may be selectively provided in the station 100.

[0052] 4 is a block diagram showing a configuration of an AP 200 according to an embodiment of the present invention. As shown in the figure, the AP 200 according to the embodiment of the present invention includes a processor 210, a communication unit 220, and a memory 260. In FIG. 4, a duplicated description of parts of the configuration of the AP 200 that are the same as or correspond to the configuration of the station 100 in FIG. 3 will be omitted.

[0053] Referring to FIG. 4, the AP 200 according to the present invention includes a communication unit 220 for operating a BSS in at least one frequency band. As described in the embodiment of FIG. 3, the communication unit 220 of the AP 200 also includes a plurality of communication modules using different frequency bands. That is, the AP 200 according to the embodiment of the present invention includes at least two communication modules among different frequency bands, for example, 2.4 GHz, 5 GHz, and 60 GHz. Preferably, the AP 200 includes a communication module using a frequency band of 6 GHz or more and a communication module using a frequency band of 6 GHz or less. Each communication module performs wireless communication with a station according to the WLAN standard of the frequency band supported by the corresponding communication module. The communication unit 220 may operate only one communication module at a time or operate multiple communication modules simultaneously according to the performance and requirements of the AP 200. In the embodiment of the present invention, the communication unit 220 represents an RF communication module for processing RF signals.

[0054] Next, the memory 260 stores control programs used in the AP 200 and various data associated therewith. Such control programs include a connection program for managing station connections. Also, the processor 210 controls each unit of the AP 200 and controls transmission and reception of data between the units. According to an embodiment of the present invention, the processor 210 executes a program for connection with a station stored in the memory 260 and transmits a communication setting message to one or more stations. At this time, the communication setting message includes information regarding connection priority conditions of each station. Also, the processor 210 performs connection setting in response to a connection request of a station. According to an embodiment, the processor 210 is a modem or a modulation / demodulation unit that modulates and demodulates wireless signals transmitted and received from the communication unit 220. The processor 210 controls various operations of transmitting and receiving wireless signals of the AP 200 according to an embodiment of the present invention. A detailed embodiment thereof will be described later.

[0055] FIG. 5 is a diagram illustrating a process in which a STA establishes a link with an AP.

[0056] 5, the link between the STA 100 and the AP 200 is set up through three steps: scanning, authentication, and association. First, the scanning step is a step in which the STA 100 acquires connection information of the BSS operated by the AP 200. There are two methods for performing scanning: a passive scanning method in which the STA 100 acquires information using only a beacon message S101 periodically transmitted by the AP 200, and an active scanning method in which the STA 100 transmits a probe request to the AP S103, receives a probe response from the AP S105, and acquires connection information.

[0057] The STA 100 that has successfully received wireless connection information in the scanning step transmits an authentication request (S107a), receives an authentication response from the AP 200 (S107b), and performs an authentication step. After the authentication step is performed, the STA 100 transmits an association request (S109a), receives an association response from the AP 200, and performs an association step (S109b). In this specification, association basically means wireless association, but the present invention is not limited thereto, and association in a broad sense includes both wireless association and wired association.

[0058] Meanwhile, an 802.1X-based authentication step S111 and an IP address acquisition step S113 via DHCP are additionally performed. In Fig. 5, the server 300 is a server that processes 802.1X-based authentication with the STA 100, and may be physically connected to the AP 200 or may exist as a separate server.

[0059] Aggregated MPDU (A-MPDU) 6 is a diagram showing an embodiment of a method for assembling MPDUs of a wireless LAN packet. In a contention-based wireless LAN system, each time a terminal attempts data transmission, the terminal must compete for channel occupation. Therefore, as the density of terminals in a BSS and the amount of transmission data per terminal increase, the efficiency of the actual data transmission amount relative to the contention time may rapidly decrease.

[0060] In order to solve this problem and improve the data transmission efficiency of the terminal, an aggregated MPDU (A-MPDU) as shown in FIG. 6 may be used. The A-MPDU is composed of one or more A-MPDU subframes and a variable amount of EOF padding. Each A-MPDU subframe includes an MPDU delimiter and can selectively include an MPDU that follows it. The MPDU delimiter indicates information about the MPDU included in the A-MPDU subframe. More specifically, the MPDU delimiter includes an EOF field, an MPDU length field, a CRC (cyclic redundancy check) field, and an MPDU signature field. The EOF length field indicates the length of the MPDU. If no MPDU exists in the MPDU subframe, the MPDU length field is set to 0. The CRC field is used to detect errors in the MPDU delimiter, and the MPDU signature field represents a pattern used by the receiver to detect the MPDU delimiter.

[0061] Hereinafter, in the embodiments of the present invention, MPDU may be used as a term representing an A-MPDU subframe composed of the MPDU for convenience. For example, an MPDU with an EOF field value set to 1 may refer to an A-MPDU subframe with an EOF field value set to 1 or an MPDU constituting the A-MPDU subframe. More specifically, an MPDU with an EOF field value set to 1 may refer to an A-MPDU subframe including an MPDU segment with an EOF field value set to 1 or an MPDU constituting the A-MPDU subframe. Also, in the embodiments of the present invention, a receiver may be used as a term representing a terminal that receives an A-MPDU and transmits a response frame thereto.

[0062] FIG. 6a is a diagram showing an embodiment of the structure of an A-MPDU. As shown in the figure, an A-MPDU may include one or more A-MPDU subframes (i.e., a pre-EOF padding section) and an EOF padding section. In the case of a TID in which a block response (BA) or agreement has been performed, multiple data frames (or data MPDUs) may be transmitted together through one A-MPDU. In this case, in an MPDU divisor for each MPDU, the EOF field value is set to 0 and the MPDU length field value is set to a non-zero value. Referring to FIG. 6a, multiple data MPDUs belonging to TID2 are transmitted through one A-MPDU. In an EOF padding section following a pre-EOF padding section, the EOF field value is set to 1, and one or more EOF divisors with the MPDU length field value set to 0 are transmitted to indicate the end of A-MPDU transmission.

[0063] FIG. 6b is a diagram showing an embodiment of a single MPDU (S-MPDU) structure. The above-mentioned A-MPDU structure may be inefficient when a sender is trying to transmit one MPDU. More specifically, when A-MPDU is used, an MPDU separator must be inserted for each MPDU, and a BlockAck-based response including a BA bitmap may be requested. Meanwhile, in the 802.11ac wireless LAN system, it is specified that all data transmitted in the PPDU (PHY Protocol Data Unit) format of the VHT PPDU is transmitted via the MPDU format of the A-MPDU. Therefore, in order to improve the inefficient transmission structure in the above-mentioned situation, when only one MPDU is transmitted within the PPDU, the S-MPDU format can be used. In the MPDU separator of a data MPDU transmitted alone in the S-MPDU format, the value of the EOF field is set to 1, and the value of the MPDU length field is set to a value other than 0. As in the A-MPDU format, EOF padding may be used in the S-MPDU format. When an S-MPDU is received, the receiver can respond with a normal Ack, not a BlockAck, regardless of whether a block response agreement between the transmitter and receiver has been performed.

[0064] 7 is a diagram illustrating an embodiment of a method for assembling MPDUs of wireless LAN packets in a non-legacy wireless LAN system. In this embodiment of the present invention, the non-legacy wireless LAN system may refer to a wireless LAN system conforming to the IEEE 802.11ax standard, and the non-legacy wireless LAN packet may refer to a High Efficiency (HE) PPDU conforming to the standard. However, the present invention is not limited thereto.

[0065] Legacy wireless LAN systems prior to the IEEE 802.11ax standard had the restriction that all MPDUs included in an A-MPDU must belong to the same TID. For example, a data MPDU and an action frame could not be aggregated in one A-MPDU. Also, since MPDUs with different TIDs could not be included in an A-MPDU, if a data MPDU with an EOF field value of 1 was included in a received A-MPDU, the receiver identified the data MPDU as the only MPDU included in the A-MPDU. Therefore, the receiver can respond with a general Ack by considering the A-MPDU as an S-MPDU.

[0066] However, in a non-legacy wireless LAN system, an A-MPDU in which MPDUs of multiple TIDs are aggregated can be transmitted in a multi-user (MU) transmission or a single user (SU) transmission that satisfies certain conditions. Such an A-MPDU in which MPDUs of multiple TIDs are aggregated is called a multi-TID A-MPDU. A multi-TID A-MPDU in a non-legacy wireless LAN system can include one or more A-MPDU subframes with the EOF field set to a value of 1.

[0067] Each MPDU of one or more A-MPDU subframes with the EOF field set to 1 must belong to a different TID and must be the only MPDU of the TID in the A-MPDU. That is, an A-MPDU subframe including an MPDU separator with the EOF field set to 1 is composed of an MPDU or an action frame requesting a general Ack response. As shown in FIG. 7a, the EOF field value of the MPDU separator preceding the only MPDU of a specific TID in the A-MPDU (i.e., the MPDU of TID1 and the MPDU of TID3) may be set to 1. Here, even in the case of a Quality of Service (QoS) data MPDU of a TID for which a block response agreement is performed, the EOF field value of the MPDU separator is set to 1 in the case of the only MPDU of the TID in the A-MPDU. Also, as shown in FIG. 7b, an action frame requesting a general Ack response may be aggregated with other data MPDUs. In this case, a maximum of one action frame can be aggregated in the A-MPDU, and the EOF field value of the MPDU delimiter preceding the action frame can be set to 1.

[0068] Meanwhile, a data MPDU of a TID for which a block response agreement has not been performed may be aggregated with data MPDUs of other TIDs by setting the value of the EOF field of the corresponding MPDU delimiter to 1. If a block response agreement has not been performed, the frame of the corresponding TID does not basically support a BlockAck response. However, since a multi-STA BlockAck (hereinafter, M-BA) supports an Ack context, a response to the MPDU of the corresponding TID may be performed using the M-BA. When a data MPDU of a TID for which a block response agreement has not been performed is transmitted through an A-MPDU, it is obvious that the MPDU is the only MPDU of the corresponding TID. Therefore, according to an embodiment of the present invention, when a data MPDU of a TID for which a block response agreement has not been performed is transmitted through an A-MPDU, the value of the EOF field of the corresponding MPDU delimiter may be set to 0. However, even in this case, if one or more other MPDUs aggregated together with the A-MPDU request an immediate response, a response to the MPDU of the corresponding TID may be performed using the M-BA.

[0069] Also, one or more MPDUs of the TID for which the block response agreement has been performed can be aggregated into the same A-MPDU by setting the value of the EOF field of the corresponding MPDU delimiter to 0. That is, one or more A-MPDU subframes with the EOF field value of 0 can be aggregated with an A-MPDU subframe with the EOF field value of 1. In a legacy wireless LAN system, if the EOF field value of the first MPDU delimiter of a received A-MPDU is 1, the MPDU of the corresponding A-MPDU subframe can be regarded as the only MPDU transmitted through the A-MPDU. That is, the received A-MPDU can be regarded as an S-MPDU as shown in FIG. 7c. However, in a non-legacy wireless LAN system, after identifying other subsequent MPDU delimiters and MPDUs, it can be determined whether the corresponding A-MPDU is an S-MPDU, a (single-TID) A-MPDU, or a multi-TID A-MPDU.

[0070] The receiver of the S-MPDU, A-MPDU, or multi-TID A-MPDU can transmit a response based on an acknowledgement context. According to an embodiment of the present invention, the acknowledgement context may include a BlockAck context, an Ack context, an All Ack context, etc., and a detailed embodiment thereof will be described later. According to an embodiment of the present invention, an A-MPDU subframe with an EOF field value set to 1 can indicate an Ack context. If an MPDU of an A-MPDU subframe with an EOF field value of 1 is transmitted alone via an A-MPDU, a response to the MPDU can be made using an Ack frame. However, if an MPDU of an A-MPDU subframe with an EOF field value of 1 is transmitted together with other frames requesting an immediate response, a response to the MPDU can be made using an M-BA frame.

[0071] When a response to an MPDU of an A-MPDU subframe in which the EOF field has a value of 1 is performed using an M-BA frame, the response to the MPDU is received through a per AID TID information field in which the BA bitmap is omitted in the M-BA frame. More specifically, a response context included in each per AID TID information in the M-BA frame may be indicated by an Ack type subfield of the per AID TID information field. According to an embodiment, a value of 1 in the Ack type subfield may indicate an Ack context, and a value of 0 in the Ack type subfield may indicate a BlockAck context. Therefore, when a response to an MPDU of an A-MPDU subframe in which the EOF field has a value of 1 is performed using an M-BA frame, the response to the MPDU may be received through a per AID TID information field in which the Ack type subfield has a value of 1 set. That is, the value of the Ack type subfield of the per AID TID information field containing response information for the MPDU (i.e., Ack type subfield = 1) is set to be different from the Ack type subfield value of another per AID TID information field requesting a BA bitmap (i.e., Ack type subfield = 0).

[0072] 8 illustrates another embodiment of a method for assembling MPDUs of a wireless LAN packet in a non-legacy wireless LAN system. As described above, since a multi-TID A-MPDU is used in a non-legacy wireless LAN system, there can be up to one A-MPDU subframe for each TID in which the EOF field value is set to 1 in one A-MPDU. That is, an A-MPDU subframe in which the EOF field value is set to 1 and multiple A-MPDU subframes in which the EOF field value is set to 0 can coexist in one A-MPDU.

[0073] In a single-TID A-MPDU used in a legacy wireless LAN system, an MPDU separator with an EOF value of 0 cannot be placed after an MPDU separator with an EOF value of 1. However, in a multiple-TID A-MPDU used in a non-legacy wireless LAN system, A-MPDU subframes with an EOF field value of 0 and A-MPDU subframes with an EOF field value of 1 are mixed, so that the EOF values ​​of the MPDU separators may be irregularly arranged. According to an embodiment of the present invention, a method of arranging multiple MPDUs in a multiple-TID A-MPDU can be set to comply with the MPDU arrangement rule in a conventional A-MPDU.

[0074] More specifically, according to an embodiment of the present invention, an A-MPDU subframe whose EOF field value is set to 1 may be configured to be located between an A-MPDU subframe whose EOF field value is set to 0 and the EOF padding. More specifically, the arrangement of MPDU division elements (or A-MPDU subframes) within an A-MPDU may be configured in the following order: First group: an MPDU separator with the value of the EOF field set to 0 and the value of the MPDU length field set to a non-zero value (in the example of FIG. 8, the MPDU separator for the MPDU of TID2). Second group: MPDU separators whose EOF field is set to a value of 1 and whose MPDU length field is set to a value other than 0 (in the example of FIG. 8, the MPDU separator for the MPDU with TID1, the MPDU separator for the MPDU with TID3, and the MPDU separator for the action frame). Third group: an MPDU segment with the value of the EOF field set to 1 and the value of the MPDU length field set to 0 (in the embodiment of FIG. 8, the EOF padding portion).

[0075] That is, the MPDU segmentation in the A-MPDU is arranged in the order of the first group, the second group, and the third group. According to an embodiment, the arrangement order of the MPDUs in the first group and / or the arrangement order of the MPDUs in the second group may not be restricted. That is, the arrangement of multiple MPDUs belonging to the same group may not be consecutive among the same TIDs, and there may be no restriction on the order between TIDs.

[0076] 9 illustrates another embodiment of a method for assembling MPDUs of a wireless LAN packet in a non-legacy wireless LAN system. A-MPDU can aggregate multiple MPDUs into one PSDU (PHY Service Data Unit). At this time, MPDUs of various types of frames are aggregated into A-MPDU. More specifically, QoS data frames, QoS Null frames, action frames, action No Ack frames, control frames, etc. can be aggregated into one A-MPDU. Among them, A-MPDUs including QoS data frames are divided into DEIR (Data Enabled Immediate Response) context and DENIR (Data Enabled No Immediate Response) context depending on whether the data frame requires an immediate response.

[0077] Whether or not a data frame requires an immediate acknowledgement can be indicated by an acknowledgement policy subfield of the QoS Control field of the MAC header. According to one embodiment, the acknowledgement policy subfield can indicate an acknowledgement policy for data via four different field values.

[0078] First, if the response policy subfield is set to a first value, the receiver responds to the data frame with a general Ack or an implicit BlockAck. If the response policy is general Ack or implicit BlockAck, an immediate response to the data frame is requested. That is, the receiver transmits an Ack frame or a BlockAck frame after SIFS from the PPDU carrying the data frame. In this case, the BlockAck frame may be transmitted separately or as part of the A-MPDU.

[0079] Next, when the response policy subfield is set to a second value, no response to the data frame is requested, i.e., when the response policy subfield is set to a second value, the response policy can be identified as No Ack.

[0080] Next, if the response policy subfield is set to a third value, an implicit Ack is requested. If the response policy is an implicit Ack, a response to the data frame is performed, but the response is not an Ack frame. According to a further embodiment of the present invention, if the response policy subfield is set to a third value, an HTP (HE TB PPDU) Ack can be requested. If a data frame is transmitted via a PPDU requesting a HE TB (high efficiency trigger-based) PPDU, and the response policy of the data frame is an HTP Ack, the recipient responds to the data frame via a HE TB PPDU.

[0081] Finally, if the Response Policy subfield is set to the fourth value, a BlockAck is requested. If the Response Policy is BlockAck, the receiver takes no action except to record its status upon receipt of the frame. The receiver may proceed with a response if a BlockAck Request frame is received.

[0082] Thus, information about whether a data frame requires an immediate response is assigned in the MAC Service Access Point (SAP), which is part of the MAC upper layer, via the service class for each TID in the form of QoSAck or QoSNoAck. For a TID with a service class assigned as QoSNoAck, no block response agreement is performed and the value of the response policy subfield of the frame for that TID is set to a second value, i.e., to indicate No Ack.

[0083] In a legacy wireless LAN system, only one MPDU of one TID can be transmitted through one A-MPDU. Therefore, when a QoS data frame or a QoS Null frame of a TID that requests an immediate response is aggregated, the A-MPDU is automatically classified as a DEIR context. Also, when a QoS data frame or a QoS Null frame of a TID that does not request an immediate response is aggregated, the A-MPDU is automatically classified as a DENIR context. Therefore, in a legacy wireless LAN system, a frame of a TID whose service class is QoSAck and a frame of another TID whose service class is QoSNoAck cannot be aggregated in one A-MPDU. However, in a non-legacy wireless LAN system, aggregation of MPDUs of different TIDs is allowed through a multi-TID A-MPDU. Therefore, in a non-legacy wireless LAN system, it is necessary to modify the context for an A-MPDU in which a frame of a TID whose service class is QoSAck and a frame of another TID whose service class is QoSNoAck are aggregated together.

[0084] First, Fig. 9a illustrates an A-MPDU of a DEIR context according to an embodiment of the present invention. An A-MPDU in which a frame of a TID whose service class is QoSAck and a frame of another TID whose service class is QoSNoAck are aggregated together may be classified as a DEIR context because an immediate response is requested by the TID whose service class is QoSAck. According to an embodiment of the present invention, a frame whose response policy is No Ack may be selectively aggregated into an A-MPDU of a DEIR context only if at least one of a frame whose response policy is Ack (or implicit BlockAck), a frame whose response policy is HTP Ack, a frame whose response policy is BlockAck, and an action frame is present.

[0085] Next, Figure 9b is a diagram showing an A-MPDU of a DENIR context according to an embodiment of the present invention. According to an embodiment of the present invention, frames of multiple TIDs whose response policy is No Ack may be aggregated together in the A-MPDU of the DENIR context. In addition, frames of one or more TIDs whose response policy is No Ack and an action No Ack frame may be aggregated together in the A-MPDU of the DENIR context.

[0086] A-MPDU response frame 10 is a diagram showing an embodiment of a response method according to an A-MPDU format. As described above, in a non-legacy wireless LAN system, A-MPDUs of the following formats may be used: i) A-MPDU in which multiple MPDUs belonging to different TIDs are aggregated (embodiment of FIG. 10a); ii) A-MPDU in which multiple MPDUs belonging to one TID are aggregated (embodiment of FIG. 10b); iii) A-MPDU including one MPDU (embodiment of FIG. 10c).

[0087] Therefore, the structure of the response frame may change depending on the format of the A-MPDU received by the receiver. According to an embodiment of the present invention, the following response frame may be transmitted for each A-MPDU format. 1) Ack frame: When there is only one MPDU in the received A-MPDU whose EOF field is set to 1, or when there is only one MPDU requesting an immediate response in the received A-MPDU. 2) Compressed BlockAck (C-BA) frame: When all MPDUs that request an immediate response in the received A-MPDU belong to the same TID. Or when the received A-MPDU is composed of only one MPDU of a TID that requests an immediate response and frames that do not request an immediate response in addition to the TID. In this case, frames that do not request an immediate response can include an action No Ack frame, a QoS data frame whose response policy is BlockAck or No Ack, a QoS Null frame whose response policy is BlockAck or No Ack, etc. 3) Multi-STA BlockAck (M-BA) frame: When the received A-MPDU is composed of MPDUs of two or more TIDs requesting an immediate response. Or, when the received A-MPDU is configured to include MPDUs of one or more TIDs requesting an immediate response and an action frame. When a response is transmitted in an M-BA frame, the response may be performed via an independent per AID TID information field for each TID. If the received A-MPDU contains an MPDU with the EOF field value set to 1, the value of the Ack type subfield of the per AID TID information field corresponding to the MPDU may be set to 1 and the BA bitmap may be omitted.

[0088] FIG. 11 is a diagram showing an embodiment of a method for a terminal to transmit a response frame for an A-MPDU. As described above, in a non-legacy wireless LAN system, a sender can transmit a multi-TID A-MPDU, and different response policies can be specified for each TID in one A-MPDU. Also, a receiver can transmit a response using any one of an Ack frame, a BlockAck frame, and an M-BA frame based on the format of the received A-MPDU. Unlike an AP, a non-AP STA does not need to receive data from multiple terminals at the same time. Therefore, the STA can perform a response to the A-MPDU based on information included in the received A-MPDU, information on the presence or absence of upstream multiple user trigger information in the A-MPDU, etc.

[0089] 11 is a diagram showing an embodiment of a response method of a STA when there is no MPDU with a response policy set to HTP Ack in the received A-MPDU. The A-MPDU transmitted by the AP is carried in a HE SU (high efficiency single-user) PPDU or HE MU (high efficiency multi-user) PPDU, which is received by the STA. If the response policy of the MPDU included in the received A-MPDU is set to HTP Ack, the receiver must respond in the HE TB PPDU format. However, if there is no MPDU with a response policy set to HTP Ack in the received A-MPDU, the STA can respond in the HE SU PPDU format.

[0090] At this time, the STA can respond with any one of an Ack frame, a BlockAck frame, and an M-BA frame carried in the HE SU PPDU based on the format of the received A-MPDU. According to an embodiment, the STA can determine the format of the response frame considering the number of TIDs for which an immediate response is requested in the MPDU of the successfully received A-MPDU, information on the MPDU segment of the A-MPDU, etc. More specifically, the STA can determine the format of the response frame based on at least one combination of the following information included in the MPDU of the successfully received A-MPDU: i) the number of TIDs for which an immediate response is requested, ii) the presence or absence of MPDU segmentation in which the EOF field value is 1 and the MPDU length field value is not 0, iii) the number of MPDUs for which a response of the Ack context is requested, and iv) the number of MPDUs for which no block response agreement is made.

[0091] First, FIG. 11a illustrates an embodiment in which a STA responds to an A-MPDU with an Ack frame carried in a HE SU PPDU. According to an embodiment of the present invention, if a successfully received MPDU in an A-MPDU is the only MPDU requesting an immediate response of an Ack context (i.e., if the received A-MPDU is identified as an S-MPDU), the STA responds with an Ack frame. Also, if a successfully received MPDU in an A-MPDU includes the only MPDU requesting an immediate response of an Ack context and one or more other MPDUs that do not require an immediate response, the STA responds with an Ack frame. That is, if a successfully received MPDU in an A-MPDU includes only one MPDU requesting an immediate response, the STA responds with an Ack frame.

[0092] In this case, the MPDU requesting an immediate response to the Ack context may include an action frame, a QoS data frame whose response policy is general Ack, a QoS Null frame whose response policy is general Ack, etc. According to an embodiment of the present invention, the MPDU requesting an immediate response to the Ack context may be followed by an MPDU divisor whose EOF field has a value of 1 and whose MPDU length field has a value other than 0. In addition, the MPDU not requesting an immediate response may include an action No Ack frame, a QoS data frame whose response policy is BlockAck or No Ack, a QoS Null frame whose response policy is BlockAck or No Ack, etc.

[0093] According to a further embodiment of the present invention, if the received A-MPDU is identified as including only one MPDU requesting an immediate response of the Ack context, the STA may respond with an M-BA frame. In this case, the STA may perform the response of the Ack context by inserting only one per AID TID information field into the M-BA frame. However, since the length of the M-BA frame is longer than the length of the Ack frame, the STA may respond with the M-BA frame only when it is possible to transmit using the MCS according to the specified rule within the duration indicated by the received MPDU.

[0094] Next, FIG. 11b illustrates an embodiment in which a STA responds to an A-MPDU with a Compressed BlockAck (C-BA) frame carried in an HE SU PPDU. According to an embodiment of the present invention, if a received A-MPDU is identified as a single-TID A-MPDU, the STA responds with a Compressed BlockAck (C-BA) frame. That is, if the successfully received MPDU in the A-MPDU includes one or more MPDUs of only one TID that request an immediate response, the STA responds with a C-BA frame. Also, if the successfully received MPDU in the A-MPDU includes one or more MPDUs of only one TID that request an immediate response and one or more other MPDUs that do not request an immediate response, the STA responds with a C-BA frame. In other words, if multiple MPDUs that request an immediate response in the successfully received MPDUs of the A-MPDU all belong to the same TID, the STA responds with a C-BA frame.

[0095] In this case, the MPDU requesting an immediate response may include a QoS data frame whose response policy is implicit BlockAck, a QoS Null frame whose response policy is implicit BlockAck, etc. According to an embodiment of the present invention, a frame whose response policy is implicit BlockAck may request an immediate response of the BlockAck context. According to an embodiment, the MPDU requesting an immediate response of the BlockAck context may be followed by an MPDU separator whose EOF field has a value of 0 and whose MPDU length field has a value other than 0. Also, the MPDU not requesting an immediate response may include an action No Ack frame, a QoS data frame whose response policy is BlockAck or No Ack, a QoS Null frame whose response policy is BlockAck or No Ack, etc. According to a further embodiment of the present invention, if the received A-MPDU is identified as a single-TID A-MPDU, the STA may respond with an M-BA frame.

[0096] Next, FIG. 11c illustrates an embodiment in which a STA responds to an A-MPDU with a Multi-STA BlockAck (M-BA) frame carried in an HE SU PPDU.

[0097] According to an embodiment of the present invention, if the received A-MPDU is identified as a multi-TID A-MPDU, the STA responds with a multi-STA BlockAck (M-BA) frame. That is, if the successfully received MPDU in the A-MPDU includes MPDUs of two or more TIDs that request an immediate response, the STA responds with an M-BA frame. Also, if the successfully received MPDU in the A-MPDU includes MPDUs of one or more TIDs that request an immediate response and an action frame, the STA responds with an M-BA frame.

[0098] According to a more specific embodiment, if the received A-MPDU satisfies at least one of the following conditions, the STA can respond with an M-BA frame: i) if the A-MPDU includes an MPDU of two or more TIDs requesting an immediate response of a BlockAck context; ii) if the A-MPDU includes an MPDU of one or more TIDs requesting an immediate response of a BlockAck context and an MPDU of one or more TIDs requesting an immediate response of an Ack context; iii) if the A-MPDU includes an MPDU of two or more TIDs requesting an immediate response of an Ack context; iv) if the A-MPDU includes an MPDU of one or more TIDs requesting an immediate response of a BlockAck context or an Ack context and an action frame.

[0099] At this time, the MPDU requesting an immediate response of the BlockAck context may include a QoS data frame whose response policy is implicit BlockAck, a QoS Null frame whose response policy is implicit BlockAck, etc. According to an embodiment, the MPDU requesting an immediate response of the BlockAck context may be followed by an MPDU divisor whose EOF field has a value of 0 and whose MPDU length field has a value other than 0. Also, the MPDU requesting an immediate response of the Ack context may include an action frame, a QoS data frame whose response policy is general Ack, a QoS Null frame whose response policy is general Ack, etc. According to an embodiment of the present invention, the MPDU requesting an immediate response of the Ack context may be followed by an MPDU divisor whose EOF field has a value of 1 and whose MPDU length field has a value other than 0.

[0100] When a response is transmitted in the M-BA frame, the response may be performed through an independent per AID TID information field for each TID. In this case, in the response to the action frame, the TID value of the per AID TID information field is set to '1111'. If an MPDU of an Ack context exists in the received A-MPDU, the value of the Ack type subfield of the per AID TID information field corresponding to the MPDU may be set to 1 and the BA bitmap may be omitted. Also, if all MPDUs included in the received A-MPDU are successfully received, the STA may insert only one per AID TID information field into the M-BA frame to perform a response to the All Ack context. In this case, the TID value of the only per AID TID information field inserted into the M-BA frame may be set to '1110' to indicate a response of the All Ack context.

[0101] 12 is a diagram showing another embodiment of a method for transmitting a response frame for an A-MPDU by a terminal, in which the embodiment of FIG 12 is the same as or similar to the embodiment of FIG 11 described above, and redundant description will be omitted.

[0102] FIG. 12 is a diagram showing an embodiment of a response method of a STA when an MPDU with a response policy set to HTP Ack exists in a received A-MPDU. The A-MPDU transmitted by the AP can be carried in an HE SU PPDU or an HE MU PPDU, and the STA receives it. If the response policy of the MPDU included in the received A-MPDU is set to HTP Ack, the receiver must respond in the HE TB PPDU format. In this case, a STA that receives an MPDU with a response policy set to HTP Ack can respond in the HE TB PPDU format only in the following cases: i) when an A-MPDU including a trigger frame with the receiver address field set to the address of the STA is received; ii) when an A-MPDU including a QoS data frame or a QoS Null frame with the receiver address field set to the address of the STA including an Uplink Multi-User Response Scheduling (UMRS) control field is received. If at least one of the trigger frame and the UMRS control field is not received, the STA cannot respond to an MPDU with a response policy set to HTP Ack. Based on the format of the received A-MPDU, the STA can respond with either an Ack frame, a BlockAck frame or an M-BA frame carried in the HE TB PPDU.

[0103] First, FIG. 12a illustrates an embodiment in which a STA responds to an A-MPDU with an Ack frame carried in a HE TB PPDU. According to an embodiment of the present invention, if the successfully received MPDU in the A-MPDU is the only MPDU requesting an immediate response of the Ack context (i.e., the received A-MPDU is identified as an S-MPDU) and includes a UMRS control field, the STA responds with an Ack frame. Also, if the successfully received MPDU in the A-MPDU includes the only MPDU requesting an immediate response of the Ack context, zero or more other MPDUs not requesting an immediate response, and a trigger frame, the STA responds with an Ack frame. That is, if the successfully received MPDU in the A-MPDU includes the only MPDU requesting an immediate response and includes a UMRS control field or a trigger frame, the STA responds with an Ack frame.

[0104] In this case, the MPDU requesting an immediate response of the Ack context may include an action frame, a QoS data frame whose response policy is HTP Ack, a QoS Null frame whose response policy is HTP Ack, etc. According to an embodiment of the present invention, the MPDU requesting an immediate response of the Ack context may be followed by an MPDU separator whose EOF field has a value of 1 and whose MPDU length field has a value other than 0. In addition, the MPDU not requesting an immediate response may include an action No Ack frame, a QoS data frame whose response policy is BlockAck or No Ack, a QoS Null frame whose response policy is BlockAck or No Ack, etc.

[0105] According to a further embodiment of the present invention, if the received A-MPDU is identified as including only one MPDU requesting an immediate response of the Ack context, the STA may respond with an M-BA frame. In this case, the STA may perform the response of the Ack context by inserting only one per AID TID information field into the M-BA frame. However, since the length of the M-BA frame is longer than the length of the Ack frame, the STA may respond with an M-BA frame only when it is possible to transmit using a modulation and coding scheme (MCS) according to a specified rule within the length indicated by the trigger information included in the received A-MPDU. In this case, the length indicated by the trigger information may be expressed through the length field of the common information field of the trigger frame or the HE TB PPDU length field of the UMRS control field of the MPDU.

[0106] Next, FIG. 12b illustrates an embodiment in which a STA responds to an A-MPDU with a compressed BlockAck (C-BA) frame carried in a HE TB PPDU. According to an embodiment of the present invention, if a received A-MPDU is identified as a single-TID A-MPDU, the STA responds with a compressed BlockAck (C-BA) frame. That is, if the successfully received MPDU in the A-MPDU includes multiple MPDUs of only one TID that request an immediate response of the BlockAck context and includes a UMRS control field or trigger frame, the STA responds with a C-BA frame. Also, if the successfully received MPDU in the A-MPDU includes multiple MPDUs of only one TID that request an immediate response of the BlockAck context and one or more other MPDUs that do not request an immediate response and includes a UMRS control field or trigger frame, the STA responds with a C-BA frame. In other words, if all successfully received MPDUs of an A-MPDU requesting an immediate response of the BlockAck context belong to the same TID and the A-MPDU includes a UMRS control field or a trigger frame, the STA responds with a C-BA frame.

[0107] In this case, the MPDU requesting an immediate response of the BlockAck context may include a QoS data frame whose response policy is HTP Ack, a QoS Null frame whose response policy is HTP Ack, etc. According to an embodiment, the MPDU requesting an immediate response of the BlockAck context may be followed by an MPDU separator whose EOF field has a value of 0 and whose MPDU length field has a value other than 0. Also, the MPDU not requesting an immediate response may include an action No Ack frame, a QoS data frame whose response policy is BlockAck or No Ack, a QoS Null frame whose response policy is BlockAck or No Ack, etc. According to a further embodiment of the present invention, if the received A-MPDU is identified as a single-TID A-MPDU, the STA may respond with an M-BA frame.

[0108] Next, FIG. 12c illustrates an embodiment in which a STA responds to an A-MPDU with a Multi-STA BlockAck (M-BA) frame carried in an HE TB PPDU.

[0109] According to an embodiment of the present invention, if the received A-MPDU is identified as a multi-TID A-MPDU, the STA responds with a multi-STA BlockAck (M-BA) frame. That is, if the successfully received MPDU in the A-MPDU includes an MPDU with two or more TIDs requesting an immediate response and includes a UMRS control field or trigger frame, the STA responds with an M-BA frame. Also, if the successfully received MPDU in the A-MPDU includes an action frame with an MPDU with one or more TIDs requesting an immediate response and includes a UMRS control field or trigger frame, the STA responds with an M-BA frame.

[0110] According to a more specific embodiment, if the received A-MPDU includes a UMRS control field or a trigger frame while satisfying at least one of the following conditions, the STA can respond with an M-BA frame: i) if the A-MPDU includes an MPDU of two or more TIDs requesting an immediate response of a BlockAck context; ii) if the A-MPDU includes an MPDU of one or more TIDs requesting an immediate response of a BlockAck context and an MPDU of one or more TIDs requesting an immediate response of an Ack context; iii) if the A-MPDU includes an MPDU of two or more TIDs requesting an immediate response of an Ack context; iv) if the A-MPDU includes an MPDU of one or more TIDs requesting an immediate response of a BlockAck context or an Ack context and an action frame.

[0111] At this time, the MPDU requesting an immediate response of the BlockAck context may include a QoS data frame whose response policy is HTP Ack, a QoS Null frame whose response policy is HTP Ack, etc. According to an embodiment, the MPDU requesting an immediate response of the BlockAck context may be followed by an MPDU divisor whose EOF field has a value of 0 and whose MPDU length field has a value other than 0. Also, the MPDU requesting an immediate response of the Ack context may include an action frame, a QoS data frame whose response policy is HTP Ack, a QoS Null frame whose response policy is HTP Ack, etc. According to an embodiment of the present invention, the MPDU requesting an immediate response of the Ack context may be followed by an MPDU divisor whose EOF field has a value of 1 and whose MPDU length field has a value other than 0.

[0112] When a response is transmitted in the M-BA frame, the response may be transmitted via an independent per AID TID information field for each TID, a specific embodiment of which is described in FIG 11c.

[0113] 13 is a diagram showing an embodiment of a method for an AP to transmit a response frame for an A-MPDU. In a non-legacy wireless LAN system, an AP can receive a PPDU transmitted by one or more STAs through an Uplink Multi-User (UL MU) transmission. Therefore, the format of the response frame and the format of the PPDU carrying the response frame can be determined according to the configuration of the A-MPDU of the PPDU received by the AP from one or more STAs.

[0114] First, FIG. 13a illustrates an embodiment in which an AP receives an A-MPDU transmitted by one or more STAs and responds with a response frame carried in an HE MU PPDU. The AP receives an A-MPDU transmitted by one or more STAs and configures a response frame for each STA according to the above-described embodiment. If a number of A-MPDUs among the received A-MPDUs request an immediate response, the AP can perform the response in the HE MU PPDU format. The AP can generate a response frame of any one of an Ack frame, a BlockAck frame, and an M-BA frame for each received A-MPDU and transmit the generated multiple response frames in the HE MU PPDU format. A specific embodiment for determining the format of a response frame for each received A-MPDU is as described above with reference to FIG. 11. The AP can transmit a response frame through a resource unit allocated to each STA. According to an embodiment of the present invention, each response frame carried in an HE MU PPDU can be transmitted through a resource unit in which the A-MPDU of each STA is transmitted.

[0115] Next, Fig. 13b illustrates an embodiment in which an AP receives an A-MPDU transmitted by one or more STAs and responds with a response frame carried in an HE SU PPDU. When an HE SU PPDU transmitted by one STA is received or only one A-MPDU among A-MPDUs transmitted by multiple STAs requests an immediate response, the AP can perform the response in the HE SU PPDU format. The AP can generate a response frame, such as an Ack frame, a BlockAck frame, or an M-BA frame, for an A-MPDU that requires an immediate response, and transmit the generated response frame in the HE SU PPDU format. A specific embodiment for determining the format of a response frame for a received A-MPDU is as described above with reference to Fig. 11.

[0116] According to a further embodiment of the present invention, if multiple A-MPDUs among the received A-MPDUs require immediate response, the AP can respond in the HE SU PPDU format. In this case, the response frame carried in the HE SU PPDU can be a group-addressed M-BA frame. The group-addressed M-BA frame can indicate response information for each STA and for each TID via the per AID TID information field.

[0117] FIG. 14 is a diagram showing a method of transmitting a response frame according to another embodiment of the present invention. According to the embodiment of FIG. 14, the A-MPDU and S-MPDU of all formats that are carried in the HE PPDU and request an immediate response can be responded to by the M-BA frame. That is, the terminal can respond to the multi-TID A-MPDU shown in FIG. 14a, the single-TID A-MPDU shown in FIG. 14b, and the S-MPDU shown in FIG. 14c collectively by the M-BA frame. When the terminal responds collectively by the M-BA frame, its implementation is simple, and the possibility of receiving a response frame of an unintended format by the sender can be eliminated. However, when it is clear that the S-MPDU has been transmitted, there is a disadvantage that the response must be performed by the M-BA frame having a larger amount of data than the Ack frame.

[0118] Operation method when some MPDUs in A-MPDU fail to be received 15 to 19 are diagrams illustrating an operation method of a terminal when at least some MPDUs of an A-MPDU fail to be transmitted. In each embodiment of FIG. 15 to 19, the same or corresponding parts as those of the previous drawings will not be described in detail.

[0119] As in the above-described embodiment, the terminal may generate an A-MPDU including one or more MPDUs requesting an immediate response, and transmit the generated A-MPDU. The receiver of the A-MPDU determines a format of a response frame based on the number of TIDs for which an immediate response is required among the successfully received MPDUs, and transmits a response frame of the determined format. That is, the response frame of the A-MPDU may be generated based on the number of TIDs for which an immediate response is required among the successfully received MPDUs. According to one embodiment, an action frame included in the successfully received MPDU is regarded as an individual TID. The terminal receives a response frame of the receiver corresponding to the A-MPDU, and determines whether the transmission of the MPDU included in the A-MPDU is successful based on the received response frame. When a response frame of a predetermined format is received according to the above-described embodiment for the A-MPDU transmitted by the terminal, the terminal may determine whether the transmission of each MPDU is successful based on response information for each MPDU included in the response frame.

[0120] Meanwhile, depending on the communication situation, the receiver may fail to receive at least some of the transmitted A-MPDUs. If the receiver fails to receive at least some of the MPDUs, the receiver may be unable to determine which of the S-MPDU, the single-TID A-MPDU, and the multiple-TID A-MPDU has been received. In particular, the upward / downward (UL / DL) OFDMA PPDU used in the non-legacy wireless LAN system includes a large amount of EOF padding to align the length of the PPDU. Therefore, the receiver may frequently fail to receive at least some of the received data and may be unable to determine the configuration of the A-MPDU. Therefore, a subsequent operation method of the communication terminal in such a situation of failure to receive some MPDUs must be defined.

[0121] According to an embodiment of the present invention, a terminal can compare a format of a response frame scheduled for a transmitted A-MPDU with a format of a response frame actually transmitted from a receiver to determine whether the transmission of an MPDU included in the A-MPDU is successful. As described above, the format of the response frame scheduled for the A-MPDU may be determined based on at least one of the number of TIDs requesting an immediate response from one or more MPDUs constituting the A-MPDU and MPDU segmentation information. Therefore, the terminal can determine whether the transmission of an MPDU included in the A-MPDU is successful by considering at least one of the number of TIDs requesting an immediate response from one or more MPDUs constituting the A-MPDU and MPDU segmentation information and the response frame transmitted corresponding to the A-MPDU.

[0122] Figure 15 illustrates a method of transmitting an A-MPDU and a response frame according to an embodiment of the present invention. Figure 15a illustrates an embodiment in which a terminal transmits an S-MPDU and a receiver fails to receive a part of the EOF padding included in the S-MPDU. Figure 15b illustrates an embodiment in which a terminal transmits a multi-TID A-MPDU and a receiver fails to receive an MPDU of a part of the TID (i.e., TID3).

[0123] 15A, the receiver receives the S-MPDU transmitted by the terminal and transmits an Ack frame in response to the S-MPDU. Since the response to the S-MPDU is expected to be an Ack frame, the terminal can determine that the S-MPDU has been successfully transmitted.

[0124] On the other hand, referring to FIG. 15b, the receiver successfully receives only some MPDUs of the multi-TID A-MPDU transmitted by the terminal. More specifically, the A-MPDU transmitted by the terminal includes MPDUs of two different TIDs (i.e., TID2 and TID3) that request an immediate response of the Ack context, but the receiver successfully receives only one of these MPDUs. Here, the MPDU that requests an immediate response of the Ack context may be followed by an MPDU separator whose EOF field has a value of 1 and whose MPDU length field has a value other than 0. In other words, in the multi-TID A-MPDU, the MPDU (and MPDU separator) of a specific TID (i.e., TID2) is successfully received, but the MPDU (and MPDU separator) of the remaining TID (i.e., TID3) is unsuccessfully received. In the embodiment of Figure 15b, the receiver successfully receives only one MPDU that requests an immediate response of the Ack context among the multiple-TID A-MPDUs transmitted by the terminal, and therefore can determine that the S-MPDU has been received, and responds to the multiple-TID A-MPDU with an Ack frame.

[0125] The terminal receives the Ack frame transmitted in response. However, since the Ack frame does not include a block response information field or a TID information field indicating the TID of the response information, the terminal cannot determine which MPDU the received Ack frame is a response for. Therefore, according to an embodiment of the present invention, when a terminal that has transmitted a multi-TID A-MPDU receives a response of an Ack frame, the terminal determines that the transmission of the multi-TID A-MPDU has failed. That is, when the transmitted A-MPDU is composed of MPDUs of multiple TIDs requesting an immediate response and the response frame transmitted corresponding to the A-MPDU is an Ack frame, it is determined that the transmission of the MPDU included in the A-MPDU has failed. Therefore, the terminal can retransmit the MPDU included in the A-MPDU determined to have failed transmission.

[0126] However, according to an embodiment of the present invention, since an Ack frame response to the A-MPDU is received, the terminal can determine that the channel access for the A-MPDU transmission is successful, apart from the MPDU included in the A-MPDU being determined to have been transmitted unsuccessfully. Therefore, the terminal can reset at least one of the EDCA parameters of the access category used for the channel access for the A-MPDU transmission. In this case, the EDCA parameters can include a contention window, a QoS short retry counter (QSRC), a QoS long retry counter (QLRC), etc.

[0127] Fig. 16 is a diagram illustrating a method for transmitting an A-MPDU and a response frame according to another embodiment of the present invention. More specifically, Fig. 16a illustrates a method for transmitting an A-MPDU response frame according to the above-mentioned embodiment, and Fig. 16b illustrates a method for transmitting an A-MPDU response frame according to a further embodiment of the present invention.

[0128] According to the embodiment of Fig. 16a, when the receiver successfully receives only one MPDU that requests an immediate response of the Ack context among the multi-TID A-MPDUs transmitted by the terminal, the receiver responds with an Ack frame. However, since the Ack frame does not include a block response information field or a TID information field indicating the TID of the response information, the terminal cannot determine which MPDU the received Ack frame is a response for.

[0129] Therefore, according to the embodiment of Fig. 16b, the receiver can determine the format of the response frame based on the reception status of each MPDU of the A-MPDU. As described above, each MPDU in the A-MPDU is followed by an MPDU separator, and the MPDU separator indicates the length information of the MPDU. Since each MPDU separator indicates the length information of the MPDU, the receiver can determine whether each MPDU and MPDU separator included in the A-MPDU has been successfully received. If the receiver successfully receives only one MPDU requesting an immediate response and fails to successfully receive at least some MPDUs, there may be other data that requires an immediate response in the MPDU that was not successfully received.

[0130] According to an embodiment of the present invention, if an unsuccessfully received MPDU may be an MPDU requesting an immediate response, the receiver may respond with an M-BA frame. For example, if at least one MPDU or MPDU fragment is not successfully received in an A-MPDU, the receiver may respond with an M-BA frame. More specifically, if at least one MPDU or MPDU fragment is not successfully received before the first received EOF padding in an A-MPDU, the unsuccessfully received MPDU may be an MPDU requesting an immediate response. Therefore, the receiver may respond with an M-BA frame. That is, even if only one MPDU requesting an immediate response in an Ack context is successfully received, if at least one MPDU or MPDU fragment is not successfully received before the first received EOF padding in an A-MPDU, the receiver responds with an M-BA frame instead of an Ack frame. In this case, in the per AID TID information field of the M-BA frame, the value of the TID subfield is set to the TID of the successfully received MPDU, the value of the Ack type subfield is set to 1, and the BA bitmap can be omitted. That is, if an A-MPDU that appears to be an S-MPDU is received and it is confirmed to be an incomplete A-MPDU, the receiver can respond with an M-BA frame that is not an Ack frame.

[0131] On the other hand, if there is an unsuccessfully received part only after the first received EOF padding in the A-MPDU, the unsuccessfully received part may be another EOF padding. Therefore, the receiver's response may not be forced to an M-BA frame. In addition, since the above problem occurs only when an error occurs in the received A-MPDU and the receiver responds with an Ack frame, the receiver may not be forced to respond to an M-BA frame in a situation where it should respond with a C-BA frame.

[0132] According to an embodiment of the present invention, the receiver can respond with an M-BA frame only if it can transmit the M-BA frame within the duration indicated by the successfully received MPDU or the length indicated by the trigger frame received in the A-MPDU. In this case, the receiver can respond with an M-BA frame only if it can transmit the M-BA frame within the duration or length using an MCS according to a specified rule.

[0133] According to another embodiment of the present invention, when an A-MPDU that appears to be an S-MPDU is received and at least a portion of the A-MPDU is not successfully received, the receiver may regard the A-MPDU as a multiple-TID A-MPDU. Since a response to a multiple-TID A-MPDU is performed via an M-BA frame, the receiver may respond to the A-MPDU with an M-BA frame.

[0134] According to a further embodiment of the present invention, the use of the M-BA frame as a response to the HE PPDU may be extended. In a non-legacy wireless LAN system, the M-BA frame can respond to A-MPDUs of the most diverse configurations, and its form can be changed so that an efficient response can be performed. Therefore, according to a further embodiment of the present invention, the M-BA frame can be universally used as a response frame in situations other than a situation in which an Ack frame is transmitted in response. For example, a non-legacy wireless LAN terminal can respond with the M-BA frame when at least some MPDUs of an A-MPDU are not successfully received and one or more successfully received MPDUs request an immediate response. Alternatively, a non-legacy wireless LAN terminal can regard the A-MPDU as a multi-TID A-MPDU when at least some MPDUs of an A-MPDU are not successfully received and one or more successfully received MPDUs request an immediate response. Therefore, the non-legacy wireless LAN terminal responds with the M-BA frame according to a response procedure for a multi-TID A-MPDU.

[0135] 17 is a diagram illustrating a method of transmitting an A-MPDU and a response frame according to another embodiment of the present invention. According to the embodiment of FIG. 17, in order to reduce the complexity of implementation, a method of transmitting a response frame that does not change the operation of a conventional receiving terminal can be used.

[0136] More specifically, when a terminal that has transmitted an A-MPDU consisting of MPDUs of multiple TIDs that require an immediate response receives an Ack frame response, the terminal can ignore the Ack frame response. Therefore, the terminal must retransmit all MPDUs that constitute the A-MPDU. However, since the terminal has received a response frame for the transmitted A-MPDU, the terminal can determine that the transmission of the A-MPDU has not failed. According to one embodiment of the present invention, the terminal can determine that the enhanced distributed channel access function (EDCAF) of the access category used for channel access in the previous A-MPDU transmission has not failed. Thus, the terminal can resume a backoff operation while maintaining EDCA parameters such as the contention window, QoS short retry counter (QSRC), and QoS long retry counter (QLRC) of the access category at their previous values. According to another embodiment of the present invention, since an Ack frame response for the A-MPDU has been received, the terminal can determine that the channel access (i.e., EDCAF) for the A-MPDU transmission has been successful. Therefore, the terminal can reset at least one EDCA parameter of the access category used for channel access for A-MPDU transmission.

[0137] Additional embodiment of S-MPDU and response frame transmission method 18 and 19 are diagrams illustrating a method of transmitting an S-MPDU and a response frame in a non-legacy wireless LAN system according to a further embodiment of the present invention.

[0138] 18 is a diagram showing a method of transmitting an S-MPDU and a response frame in a non-legacy wireless LAN system according to an embodiment of the present invention. As described above, the legacy wireless LAN system does not allow the construction of a multi-TID A-MPDU. Also, since only one A-MPDU subframe with an EOF field value set to 1 can exist per TID in an A-MPDU, it was clear that the A-MPDU subframe with an EOF field value set to 1 was the only A-MPDU subframe in the A-MPDU. Therefore, the receiver could respond with an Ack frame while excluding other possibilities.

[0139] However, in non-legacy wireless LAN systems, the configuration of a multi-TID A-MPDU is permitted. Therefore, in addition to an MPDU requesting an immediate response of an Ack context, MPDUs of other TIDs requesting an immediate response of an Ack context, multiple MPDUs with the EOF field value set to 0, action frames, QoS data / Null frames not requesting an immediate response, and action No Ack frames are permitted to be aggregated and transmitted together.

[0140] In a legacy wireless LAN system, if a received A-MPDU includes only one MPDU and the MPDU requests an immediate response of the Ack context, it can be classified as an S-MPDU. Therefore, the receiver can respond with an Ack frame. However, in a non-legacy wireless LAN system, even if a received A-MPDU includes only one MPDU that requests an immediate response, if it is aggregated with one or more other MPDUs that do not request an immediate response, it can be classified as an A-MPDU instead of an S-MPDU. In this case, the MPDU that does not request an immediate response can include an action No Ack frame, a QoS data frame with a response policy of BlockAck or No Ack, a QoS Null frame with a response policy of BlockAck or No Ack, a control response (e.g., Ack, BlockAck), etc. Therefore, in the above situation, the receiver cannot respond with an Ack frame. In addition, if the A-MPDU is considered a single-TID A-MPDU, the receiver must respond with a C-BA frame, which may be inefficient since omitting the BA bitmap by setting the Ack type subfield is not possible.

[0141] Thus, according to one embodiment of the present invention shown in Figure 18a, if a received A-MPDU contains only one MPDU requesting an immediate acknowledgement of the Ack context, the receiver may consider the A-MPDU to be an S-MPDU even if it is aggregated with one or more other MPDUs that do not request an immediate acknowledgement, and therefore the receiver responds with an Ack frame.

[0142] According to another embodiment of the present invention shown in Fig. 18b, if a received A-MPDU includes only one MPDU requesting an immediate response of the Ack context and one or more other MPDUs not requesting an immediate response, the STA may regard the A-MPDU as a multi-TID A-MPDU. Therefore, the receiver responds with an M-BA frame. However, the value of the Ack type subfield of the per AID TID information field corresponding to the MPDU requesting an immediate response may be set to 1 and the BA bitmap may be omitted.

[0143] 19 is a diagram showing a method of transmitting an S-MPDU and a response frame in a non-legacy wireless LAN system according to another embodiment of the present invention. When an A-MPDU is carried in a downstream HE MU PPDU, trigger information must be transmitted together with the MPDU, except for the MPDU whose response policy is general Ack, in order for the receiver to respond. At this time, the trigger information may be transmitted through a trigger frame or a UMRS control field included in a MAC header. However, a terminal that cannot receive the UMRS control field cannot respond unless it receives an MPDU requesting an immediate response of the Ack context together with the trigger frame.

[0144] Therefore, according to one embodiment of the present invention, if a received A-MPDU contains only one MPDU requesting an immediate response of the Ack context, the receiver may consider the A-MPDU as an S-MPDU even if a trigger frame is aggregated with it, and therefore respond with an Ack frame.

[0145] More specifically, referring to Fig. 19a, if a received A-MPDU includes only one MPDU requesting an immediate response of the Ack context and a trigger frame, the STA can regard the A-MPDU as an S-MPDU. Also, referring to Fig. 19b, if a received A-MPDU includes only one MPDU requesting an immediate response of the Ack context, one or more other MPDUs not requesting an immediate response, and a trigger frame, the STA can regard the A-MPDU as an S-MPDU. Therefore, the receiver responds to the received A-MPDU with an Ack frame.

[0146] According to another embodiment of the present invention shown in Fig. 19c, in the situation shown in Fig. 19a or 19b, the receiver can regard the A-MPDU as a multi-STA A-MPDU. Therefore, the receiver responds with an M-BA frame. However, the value of the Ack type subfield of the per AID TID information field corresponding to the MPDU requesting an immediate response can be set to 1 and the BA bitmap can be omitted.

[0147] TID aggregation limits The AP can indicate the maximum number of TIDs that each A-MPDU transmitted by each wireless communication terminal can have by using the trigger information. In this case, the trigger information can be transmitted through at least one of a trigger frame and a UMRS control field included in a MAC header. The operation of the AP indicating the maximum number of TIDs that each A-MPDU transmitted by each wireless communication terminal can have by using a trigger frame will be described with reference to Figures 20 to 24.

[0148] FIG. 20 is a diagram illustrating an operation of a wireless communication terminal transmitting an A-MPDU based on information on the maximum number of TIDs according to an embodiment of the present invention.

[0149] The AP can use the trigger frame to indicate information on the type of MPDU included in the A-MPDU transmitted by the wireless communication terminal to the AP. As described above, the AP can use the trigger frame to indicate the maximum number of TIDs that the A-MPDU transmitted by the wireless communication terminal to the AP can have. Specifically, the AP can use the User Info field of the trigger frame to indicate the maximum TID transmitted by the wireless communication terminal corresponding to the User Info field. In a specific embodiment, the AP can use the TID Aggregation Limit field of the User Info field of the trigger frame to indicate the maximum TID transmitted by the wireless communication terminal corresponding to the User Info field. At this time, the wireless communication terminal that receives the trigger frame can set the number of TIDs that the A-MPDU can have based on the trigger frame. Specifically, the wireless communication terminal that receives the trigger frame can set the number of TIDs that the MPDU included in the A-MPDU has based on the maximum number of TIDs indicated by the trigger frame, and transmit the A-MPDU to the AP. For example, a wireless communication terminal that receives a trigger frame can set the number of TIDs in the MPDU included in the A-MPDU so that the number does not exceed the maximum number of TIDs indicated by the trigger frame, and transmit the A-MPDU to the AP. Through this, the AP can efficiently manage the scoreboard. Also, the length of the BA bitmap for each of multiple wireless communication terminals can be adjusted.

[0150] In a specific embodiment, the value of the TID Aggregation Limit field may indicate the maximum number of TIDs that an A-MPDU transmitted to an AP by a wireless communication terminal that has received a trigger frame may have. For example, if the TID Aggregation Limit field is a 3-bit field having a value from 0 to 7, each of the values ​​from 0 to 7 may indicate that the maximum number of TIDs that an A-MPDU transmitted to an AP may have is one of 1 to 8.

[0151] In another specific embodiment, the AP may use the trigger frame to indicate that the wireless communication terminal designated by the trigger frame cannot generate an A-MPDU to be transmitted to the AP by aggregating MPDUs having a TID. Specifically, the AP may set a TID Aggregation Limit field to 0 to indicate that the wireless communication terminal designated by the trigger frame cannot generate an A-MPDU to be transmitted to the AP by aggregating MPDUs having a TID. However, if the A-MPDU is an MPDU without a TID but includes an MPDU requesting an immediate response, the size of the BA frame transmitted by the receiver in response to the A-MPDU may increase. In addition, the receiver may be burdened with managing the scoreboard. In this case, the immediate response may indicate that the receiver transmits a response to the transmitter within a pre-specified period within the same Transmission Opportunity (TXOP). Specifically, the pre-specified period may be a Short Inter-Frame Space (SIFS).

[0152] In another specific embodiment, the AP may use the trigger frame to indicate that the wireless communication terminal designated by the trigger frame cannot generate an A-MPDU to be transmitted to the AP by aggregating MPDUs requesting an immediate response. In this case, the MPDU requesting an immediate response may include an MPDU including Quality of Service (QoS) data having a TID. Also, the MPDU requesting an immediate response may include a Management MPDU (MMPDU) requesting an immediate response. Specifically, the MPDU requesting an immediate response may include an action frame. The AP may set a value of a TID Aggregation Limit field in a User Info field of the trigger frame to 0, and indicate in the User Info field that the wireless communication terminal corresponding to the User Info field cannot generate an A-MPDU to be transmitted to the AP by aggregating MPDUs requesting an immediate response. If the TID Aggregation Limit field value indicates a value other than 0, it may indicate the maximum number of TIDs that the A-MPDU to be transmitted to the AP by the wireless communication terminal designated by the trigger frame may have. Also, when the trigger frame indicates that the wireless communication terminal cannot generate an A-MPDU for aggregating MPDUs for which an immediate response is requested and transmitting them to the AP, the wireless communication terminal can generate an A-MPDU for aggregating MPDUs for which an immediate response is not requested and transmitting them to the AP. Specifically, when the TID Aggregation Limit field value of the User Info field corresponding to the wireless communication terminal of the trigger frame is 0, the wireless communication terminal can generate an A-MPDU for aggregating MPDUs for which an immediate response is not requested and transmitting them to the AP. In a specific embodiment, the MPDU for which an immediate response is not requested may include an MPDU including QoS data for which a response policy is set to No Ack. The response policy being set to No Ack means that an ACK for the corresponding frame is not requested. Also, the MPDU for which an immediate response is not requested may include a QoS Null frame. In this case, the QoS Null frame may be a QoS Null frame for which a response policy is set to No Ack.In addition, an MPDU that does not require an immediate response can include a No Ack action frame.

[0153] In addition, the AP can use the trigger frame to instruct a wireless communication terminal designated by the trigger frame to generate an A-MPDU by aggregating MPDUs without any limit on the number of TIDs and transmit the generated A-MPDU to the AP. Specifically, the AP can set the value of the TID Aggregation Limit field in the User Info field of the trigger frame to 7 to instruct a wireless communication terminal corresponding to the User Info field to generate an A-MPDU by aggregating MPDUs without any limit on the number of TIDs and transmit the generated A-MPDU to the AP.

[0154] In the embodiment of FIG. 20, the AP sets the value of the TID Aggregation Limit field of the User Info field corresponding to the third station of the trigger frame to 3, thereby indicating that the maximum number of TIDs that the A-MPDU that the third station (STA3) can have to transmit to the AP is 3. The third station (STA3) determines the number of TIDs of the A-MPDU to be transmitted to the AP based on the value of the TID Aggregation Limit field of the User Info field corresponding to the third station of the trigger frame. Specifically, the third station (STA3) determines the number of TIDs of the A-MPDU to be transmitted to the AP to be 3 based on the value of the TID Aggregation Limit field of the User Info field corresponding to the third station of the trigger frame. The third station (STA3) aggregates the MPDU with TID 1, the MPDU with TID 2, the MPDU with TID 3, the action frame, and the QoS Null frame to generate the A-MPDU to be transmitted to the AP. The third station (STA3) transmits the generated A-MPDU to the AP. The AP transmits M-BA frames to a plurality of wireless communication terminals including the third station (STA3) based on the A-MPDU received from the third station (SAT3). Through this embodiment, the AP adjusts the duration of the M-BA frame. In the embodiment of FIG. 20, the third station (STA3) processes that all MPDUs that do not have a TID, together with the QoS Null frame and the action frame, are not included in the number of TIDs that indicates the maximum number of TIDs. However, if there is no agreement on a block response for a specific TID, the response to the MPDU that has the TID may not affect the M-BA frame. Also, as described above, even if the MPDU does not correspond to a specific TID, an immediate response may be requested. Therefore, a specific embodiment is required in which the number of TIDs in the A-MPDU that the wireless communication terminal transmits to the AP is compared with the maximum number of TIDs. This will be described in detail with reference to FIG. 21 to FIG. 24.

[0155] FIG. 21 is a diagram illustrating an operation of a wireless communication terminal transmitting an A-MPDU based on maximum number information of TIDs according to another embodiment of the present invention.

[0156] The AP can use the trigger frame to indicate the maximum number of TIDs having a block response agreement that the A-MPDU transmitted by the wireless communication terminal can have. The wireless communication terminal can calculate the number of TIDs the A-MPDU has based on the number of TIDs having a block response agreement. In the above-mentioned embodiment, when the wireless communication terminal compares the number of TIDs the A-MPDU transmitted to the AP has with the maximum number of TIDs, the wireless communication terminal can compare the number of TIDs having a block response agreement with the maximum number of TIDs. Specifically, when the wireless communication terminal compares the number of TIDs the A-MPDU transmitted to the AP has with the maximum number of TIDs, the wireless communication terminal does not need to calculate the TIDs without a block response agreement with the number of TIDs in the A-MPDU. This is because the receiver does not store data corresponding to the TIDs without a block response agreement in a buffer and immediately transmits it to an upper layer, so the reception of data corresponding to the TIDs without a block response agreement does not affect the scoreboard management. In addition, when the wireless communication terminal counts TIDs without a block response agreement based on the number of TIDs, buffer management and A-MPDU configuration may be limited. Specifically, when the value of the TID Aggregation Limit field is 1 to 6, the wireless communication terminal may generate an A-MPDU in which the number of TIDs with a block response agreement is equal to or less than the value of the TID Aggregation Limit field, and transmit the generated A-MPDU to the AP. At this time, the wireless communication terminal may add MPDUs corresponding to TIDs without a block response agreement to the A-MPDU regardless of the value of the TID Aggregation Limit field. In addition, the AP may set the value of the TID Aggregation Limit field of the trigger frame to 0, and instruct the wireless communication terminal corresponding to the Per User Info field to aggregate MPDUs that do not request an immediate response, regardless of whether the TID is a TID with a block response agreement, to generate an A-MPDU and transmit it to the AP.Specifically, when the TID Aggregation Limit field value of the User Info field corresponding to the wireless communication terminal of the trigger frame is 0, the wireless communication terminal can generate an A-MPDU to aggregate MPDUs that do not request an immediate response and transmit them to the AP.

[0157] In the embodiment of FIG. 21, the AP sets the value of the TID Aggregation Limit field in the User Info field corresponding to the third station of the trigger frame to 3, and indicates that the maximum number of TIDs for which a block response agreement can be included in the A-MPDU transmitted by the third station (STA3) to the AP is 3. The third station (STA3) determines the number of TIDs for which a block response agreement can be included in the A-MPDU transmitted to the AP based on the value of the TID Aggregation Limit field in the User Info field corresponding to the third station of the trigger frame. The third station (STA3) determines that the A-MPDU transmitted to the AP has 3 TIDs for which a block response agreement can be included based on the value of the TID Aggregation Limit field in the User Info field corresponding to the third station of the trigger frame. A block response agreement is included for TIDs 1, 2, and 4, and no block response agreement is included for TID 5. Therefore, the third station (STA3) aggregates the MPDU with TID 1, the MPDU with TID 2, the MPDU with TID 3, the MPDU with TID 5, the action No Ack frame, and the QoS Null frame to generate an A-MPDU to be transmitted to the AP. The third station (STA3) transmits the generated A-MPDU to the AP. The AP transmits an M-BA frame to a plurality of wireless communication terminals including the third station (STA3) based on the A-MPDU received from the third station (SAT3). Through this embodiment, the AP adjusts the duration of the M-BA frame.

[0158] Data corresponding to a TID without a block response agreement can also request ACK frame transmission. In this case, the receiver can transmit an M-BA frame including a Per AID TID field that does not include a BA bitmap as a response to an MPDU corresponding to a TID without a block response agreement. Therefore, even an MPDU corresponding to a TID without a block response agreement can affect the duration of the M-BA frame. Therefore, the maximum number of TIDs that an A-MPDU can have can be calculated based on the number of TIDs requesting an immediate response and the number of frames without a TID requesting an immediate response. This will be described in detail with reference to FIG. 22.

[0159] FIG. 22 is a diagram illustrating an operation of a wireless communication terminal transmitting an A-MPDU based on maximum number information of TIDs according to still another embodiment of the present invention.

[0160] The AP can limit the number of MPDUs for which an immediate response is requested that can be included in the A-MPDU transmitted by the wireless communication terminal using a trigger frame. Specifically, the AP can indicate the number of TIDs for which an immediate response is requested that can be included in the A-MPDU transmitted by the wireless communication terminal using a trigger frame. The wireless communication terminal can calculate the number of TIDs included in the A-MPDU based on the number of TIDs for which an immediate response is requested. In the above-mentioned embodiment, when the wireless communication terminal compares the number of TIDs included in the A-MPDU transmitted to the AP with the maximum number of TIDs, the wireless communication terminal can compare the number of TIDs included in the A-MPDU for which an immediate response is requested with the maximum number of TIDs. When the wireless communication terminal compares the number of TIDs included in the A-MPDU transmitted to the AP with the maximum number of TIDs, the wireless communication terminal can calculate the number of TIDs of the A-MPDU without considering the MPDU for which an immediate response is not requested. Therefore, the wireless communication terminal can collect MPDUs corresponding to TIDs for which no immediate response is requested, regardless of the maximum number of TIDs. Also, the wireless communication terminal can collect frames without TIDs for which no immediate response is requested, regardless of the maximum number of TIDs. Also, the number of TIDs for which an immediate response is requested is the sum of the number of frames without TIDs for which an immediate response is requested, which are included in the A-MPDU, and the number of TIDs for which an immediate response is requested, which are included in the A-MPDU. The number of frames without TIDs can indicate the type of frames without TIDs. Also, an action frame with TID 15 displayed in the per AID TID field of the M-BA frame may be one of the frames without TIDs for which no immediate response is requested. The MPDU corresponding to the TID for which no immediate response is requested may be an MPDU corresponding to a TID for which a response policy is set to No Ack. Also, the MPDU corresponding to the TID for which no immediate response is requested may be a QoS Null frame. In this case, the response policy of the QoS Null frame may be No Ack. Additionally, a frame without a TID that does not request an immediate response may be an Action No Ack frame.

[0161] As described above, the AP sets the value of the TID Aggregation Limit field of the Per User Info of the trigger frame to 0, and instructs the wireless communication terminal corresponding to the Per User Info field to aggregate MPDUs that do not request an immediate response, generate an A-MPDU, and transmit the A-MPDU to the AP, regardless of whether the TID is a TID with a block response agreement. Specifically, when the TID Aggregation Limit field value of the User Info field corresponding to the wireless communication terminal of the trigger frame is 0, the wireless communication terminal can aggregate MPDUs that do not request an immediate response, and generate an A-MPDU to transmit to the AP.

[0162] In the embodiment of Fig. 22, the AP sets the value of the TID Aggregation Limit field of the User Info field corresponding to the third station of the trigger frame to 3, and indicates that the maximum value of the sum of the number of TIDs for which an immediate response is requested that the A-MPDU transmitted by the third station (STA3) may have and the number of frames without a TID for which an immediate response is requested that the A-MPDU includes is 3. The third station (STA3) determines the total number of TIDs for which an immediate response is requested that the A-MPDU transmitted to the AP includes and the number of frames without a TID for which an immediate response is requested based on the value of the TID Aggregation Limit field of the User Info field corresponding to the third station of the trigger frame. The third station (STA3) determines the total number of TIDs for which an immediate response is requested that the A-MPDU transmitted to the AP includes and the number of frames without a TID for which an immediate response is requested that the A-MPDU includes is 3 based on the value of the TID Aggregation Limit field of the User Info field corresponding to the third station of the trigger frame. TIDs 1 and 2 request an immediate response, and the response policy for TIDs 4 and 5 is set to No Ack. Also, the action frame requests an immediate response. Therefore, the third station (STA1) aggregates the MPDU with TID 1, the MPDU with TID 2, the MPDU with TID 4, the MPDU with TID 5, the action frame, the action No Ack frame, and the QoS Null frame to generate an A-MPDU to be transmitted to the AP. The third station (STA3) transmits the generated A-MPDU to the AP. The AP transmits an M-BA frame to a plurality of wireless communication terminals including the third station (STA3) based on the A-MPDU received from the third station (SAT3). Through this embodiment, the AP adjusts the duration of the M-BA frame.

[0163] FIG. 23 is a diagram illustrating an operation of a wireless communication terminal transmitting an A-MPDU based on maximum number information of TIDs according to still another embodiment of the present invention.

[0164] A multi-TID A-MPDU cannot contain multiple action frames. Therefore, a multi-TID A-MPDU can only contain one action frame. Also, if an A-MPDU contains an additional action frame, the length of the M-BA frame becomes about 2 octets longer. Therefore, the change in M-BA duration caused by adding an action frame to an A-MPDU is negligible. Also, action frames are considered to be more important than QoS data frames.

[0165] When the wireless communication terminal compares the number of TIDs in the A-MPDU to be transmitted to the AP with the maximum number of TIDs, the wireless communication terminal may not calculate the number of action frames as the number of TIDs in the A-MPDU. Specifically, when the value of the TID Aggregation Limit field is within a pre-specified range, the wireless communication terminal may aggregate action frames regardless of the value of the TID Aggregation Limit field to generate an A-MPDU to be transmitted to the AP. Specifically, in the embodiments of Figures 20 to 22, the wireless communication terminal may not calculate the number of action frames as the number of TIDs in the A-MPDU.

[0166] In the embodiment of Figure 23, the AP sets the value of the TID Aggregation Limit field in the User Info field corresponding to the third station of the trigger frame to 2, and indicates that the maximum total number of TIDs requesting an immediate response that can be included in the A-MPDU transmitted by the third station (STA3) to the AP and the total number of frames without TIDs requesting an immediate response that are included in the A-MPDU excluding action frames is 3. At this time, action frames are excluded from the calculation of the maximum value. The third station (STA3) determines the total number of TIDs requesting an immediate response that can be included in the A-MPDU transmitted to the AP and the total number of frames without TIDs requesting an immediate response that are included in the A-MPDU excluding action frames based on the value of the TID Aggregation Limit field in the User Info field corresponding to the third station of the trigger frame. The third station (STA3) determines that the A-MPDU to be transmitted to the AP has two TIDs for which an immediate response is requested based on the value of the TID Aggregation Limit field of the User Info field corresponding to the third station of the trigger frame. TIDs 1 and 2 request an immediate response, and the response policy for TIDs 4 and 5 is set to No Ack. Also, the action frame is excluded from the number calculation. Therefore, the third station (STA1) aggregates the MPDU with TID 1, the MPDU with TID 2, the MPDU with TID 4, the MPDU with TID 5, the action frame, the action No Ack frame, and the QoS Null frame to generate the A-MPDU to be transmitted to the AP. The third station (STA3) transmits the generated A-MPDU to the AP. The AP transmits the M-BA frame to a plurality of wireless communication terminals including the third station (STA3) based on the A-MPDU received from the third station (SAT3). Through this embodiment, the AP adjusts the duration of the M-BA frame.

[0167] The AP can use the trigger information to instruct a wireless communication terminal transmitting a response to the trigger information to perform channel sensing before transmitting the response. Specifically, the AP can set a CS Required field value of the trigger information to instruct a wireless communication terminal transmitting a response to the trigger information to perform channel sensing before transmitting the response. The CS Required field indicates whether channel sensing is required when the wireless communication terminal transmits a response to the trigger information. At this time, when the value of the CS Required field is 1, the CS Required field can indicate that channel sensing is required. In addition, the wireless communication terminal receiving the trigger information can determine whether to perform channel sensing based on the CS Required field of the trigger information when transmitting a response to the trigger information. Specifically, when the value of the CS Required field of the trigger information is 1, the wireless communication terminal receiving the trigger information can perform channel sensing when transmitting a response to the trigger information. At this time, the channel sensing can indicate sensing whether a channel transmitting a response to the trigger information is idle. In addition, the channel sensing can indicate a CCA operation.

[0168] FIG. 24 is a diagram illustrating an operation of a wireless communication terminal setting maximum number information of TIDs of a trigger frame according to an embodiment of the present invention.

[0169] When the AP uses the trigger information to trigger an immediate response to data transmission, the AP can use the trigger information to indicate that channel sensing is not required when the wireless communication terminal transmits a response to the trigger information. Specifically, when the AP uses the trigger information to trigger an immediate response to data transmission and the value of the length field of the common info field of the trigger information is equal to or less than a pre-specified value, the AP can use the trigger information to indicate that channel sensing is not required when the wireless communication terminal transmits a response to the trigger information. In this case, the length field indicates information on the length of the trigger-based PPDU. Specifically, the length field can indicate information on the length of the trigger-based PPDU. In addition, the pre-specified value may be 418 bytes. This allows the AP to prevent the wireless communication terminal transmitting the response to the trigger information from being unable to transmit the immediate response due to channel sensing. In this case, an operation of the wireless communication terminal transmitting both the response to the trigger information and data becomes an issue. This is because when a wireless communication terminal operating in EDCA transmits data, the wireless communication terminal can transmit data after necessarily performing channel sensing. In addition, when a wireless communication terminal transmitting a response to trigger information transmits an MPDU requesting an immediate response, an additional transmission sequence is required.

[0170] If channel sensing is not required when a wireless communication terminal indicated by the trigger frame transmits a response to the trigger information, the wireless communication terminal may generate an A-MPDU by aggregating only MPDUs that do not request an immediate response, and transmit the generated A-MPDU. Specifically, if channel sensing is not required when a wireless communication terminal indicated by the trigger frame transmits a response to the trigger information, the AP may set the value of the TID Aggregation Limit field of the User Info field of the trigger frame to 0 to indicate that a wireless communication terminal indicated by the User Info field cannot generate an A-MPDU by aggregating MPDUs that request an immediate response. Specifically, when the AP triggers an immediate response to data transmission using the trigger information, and the value of the length field of the common info field of the trigger information is equal to or less than a pre-specified value, the AP may indicate that a wireless communication terminal indicated by the trigger frame cannot generate an A-MPDU by aggregating MPDUs that request an immediate response, and transmit the generated A-MPDU. In these embodiments, the wireless communication terminal may generate an A-MPDU by aggregating MPDUs that do not require an immediate response, and transmit the generated A-MPDU to the AP.

[0171] In the embodiment of FIG. 24, the AP transmits HE MU PPDUs to a plurality of stations. At this time, the HE MU PPDU includes a trigger frame requesting an immediate response to the data MPDU included in the HE MU PPDU. In addition, the value of the length field of the Common Info field of the trigger frame is 418. In addition, the CS required bit of the trigger frame is set to 0. Therefore, the AP sets the value of the TID Aggregation Limit field of the User Info field of the trigger frame to 0. The wireless communication terminal that receives the trigger frame with the CS required bit set to 0 can transmit both a response to the data MPDU included in the HE MU PPDU and an A-MPDU including an MPDU that does not request an immediate response. At this time, the length of the length field of the trigger frame that triggers a trigger-based PPDU (HE TB PPDU) including the A-MPDU is less than or equal to 418. Therefore, the first station transmits an A-MPDU including a BA frame and an MPDU including data with a response policy of No Ack. The second station transmits an A-MPDU including a BA frame and an action No Ack frame, and the third and fourth stations transmit A-MPDUs including a BA frame and a QoS Null frame.

[0172] Although the present invention has been described above using wireless LAN communication as an example, the present invention is not limited thereto and can be equally applied to other communication systems such as cellular communication, etc. Also, although the method, apparatus and system of the present invention have been described with reference to specific embodiments, some or all of the components and operations of the present invention may be implemented using a computer system having a general-purpose hardware architecture.

[0173] The above-described embodiments of the present invention may be implemented in a variety of ways, for example, in hardware, firmware, software, or a combination thereof.

[0174] In the case of a hardware implementation, the methods according to the embodiments of the present invention may be implemented using one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, etc.

[0175] In the case of implementation by firmware or software, the method according to the embodiment of the present invention may be implemented in the form of modules, procedures, or functions that perform the functions or operations described above. The software code is stored in a memory and implemented by a processor. The memory may be located inside or outside the processor and may exchange data with the processor by various means known in the art.

[0176] The above description of the present invention is for illustrative purposes only, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical idea or essential features of the present invention. Therefore, the above-described embodiments should be interpreted as illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed form, and each component described as a distributed form may be implemented in a combined form.

[0177] The scope of the present invention is indicated by the claims set forth below rather than by the above detailed description, and all modifications and variations derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. [Industrial Applicability]

[0178] Although various embodiments of the present invention have been described with reference to an IEEE 802.11 system, the present invention may be applied to various other types of mobile communication devices, mobile communication systems, and the like. [Explanation of symbols]

[0179] 100 Stations 110 Processor 120 Communications Department 140 User Interface Section 150 display units 160 Memory

Claims

1. A wireless communication terminal, A processor; A communication unit, The processor, receiving, via the communication unit, an aggregate MPDU (A-MPDU) comprising one or more MAC Protocol Data Units (MPDUs); the A-MPDU includes at least one MPDU identifier and one or more traffic IDs (TIDs) associated with the one or more MPDUs; receiving the at least one MPDU segmentation information, each of the at least one MPDU segmentation information including an end of frame (EOF) field and a length field; and transmitting a response frame of a specific format in response to the A-MPDU through the communication unit; The particular format of the response frame is determined based on at least one of a number of at least one TID of the successfully received MPDU among one or more TIDs, or a combination of the EOF field and the length field; the at least one TID solicits immediate responses to successfully received MPDUs; Wireless communication terminal.

2. The wireless communication terminal according to claim 1, wherein the specific format is determined by further taking into consideration whether a first MPDU division information in which the EOF field has a value of 1 and the length field has a value other than 0, or a second MPDU division information in which the EOF field has a value of 0 and the length field has a value other than 0, is included.

3. 2. The wireless communication terminal of claim 1, wherein the specific format of the response frame is determined to be a format of an Ack frame when the one or more MPDUs include only one MPDU soliciting an immediate response, and the only MPDU soliciting an immediate response follows the MPDU separator information, the value of the EOF field is equal to 1, and the value of the length field is not 0.

4. 2. The wireless communication terminal of claim 1, wherein the specific format of the response frame is determined as a format of a compressed BlockAck frame when the at least one TID is the same and the at least one TID soliciting an immediate response follows MPDU separator information with a value of the EOF field equal to 0.

5. The wireless communication terminal of claim 1 , wherein the specific format of the response frame is determined as a format of a multi-STA BlockAck frame when the one or more MPDUs includes at least one MPDU of at least one TID.

6. 2. The wireless communication terminal of claim 1, wherein the response frame is carried in a high efficiency single-user PHY protocol data unit (HE SU PPDU) if no MPDU with a response policy set to HE TB PPDU (HTP) Ack is present in the A-MPDU.

7. 2. The wireless communication terminal of claim 1, wherein the response frame is carried in a high-efficiency trigger-based PHY protocol data unit (HE TB PPDU) when the A-MPDU includes a trigger frame or when the A-MPDU includes a QoS data frame or a QoS Null frame having an Uplink Multi-User Response Scheduling (UMRS) control field.

8. The wireless communication terminal according to claim 7, wherein an MPDU that solicits an immediate response and is included in the A-MPDU includes at least one of a QoS data frame with a response policy set to HTP Ack and a QoS Null frame with a response policy set to HTP Ack.

9. A wireless communication method for a wireless communication terminal, comprising: receiving an aggregate MPDU (A-MPDU) consisting of one or more MAC Protocol Data Units (MPDUs); the A-MPDU includes at least one MPDU identifier and one or more traffic IDs (TIDs) associated with the one or more MPDUs; receiving the at least one MPDU segmentation information, each of the at least one MPDU segmentation information including an end of frame (EOF) field and a length field; transmitting a response frame of a specific format in response to the A-MPDU; The particular format of the response frame is determined based on at least one of a number of at least one TID of the successfully received MPDU among one or more TIDs, or a combination of the EOF field and the length field; the at least one TID solicits an immediate response to a successfully received MPDU. A wireless communication method.

10. The wireless communication method of claim 9, wherein the specific format is determined by further considering whether a first MPDU division information in which the EOF field has a value of 1 and the length field has a value other than 0, or a second MPDU division information in which the EOF field has a value of 0 and the length field has a value other than 0, is included.

11. 10. The wireless communication method of claim 9, wherein the specific format of the response frame is determined to be a format of an Ack frame when one or more MPDUs include a single MPDU soliciting an immediate response, and the single MPDU soliciting an immediate response has a value of the EOF field equal to 1 and a value of the length field not equal to 0 following the MPDU separator information.

12. 10. The wireless communication method of claim 9, wherein the particular format of the response frame is determined as a format of a compressed BlockAck frame if the at least one TID is the same and the at least one TID soliciting an immediate response follows the MPDU separator information with a value of the EOF field equal to 0.

13. The wireless communication method of claim 9 , wherein the specific format of the response frame is determined as a format of a multi-STA BlockAck frame if the one or more MPDUs includes at least one MPDU of at least one TID.

14. 10. The wireless communication method of claim 9, wherein the response frame is carried in a High Efficiency Single User PHY Protocol Data Unit (HE SU PPDU) if no MPDU with a response policy set to HE TB PPDU (HTP) Ack is present in the A-MPDU.

15. 10. The wireless communication method of claim 9, wherein the response frame is carried in a high-efficiency trigger-based PHY protocol data unit (HE TB PPDU) when the A-MPDU includes a trigger frame or when the A-MPDU includes a QoS data frame or a QoS Null frame having an Uplink Multi-User Response Scheduling (UMRS) control field.

16. The wireless communication method of claim 15, wherein the MPDU that solicits the immediate response and is included in the A-MPDU includes at least one of a QoS data frame with a response policy set to HTP Ack and a QoS Null frame with a response policy set to HTP Ack.

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