KR20210093390A - Wireless communication method and wireless communication terminal - Google Patents

Abstract

A wireless communication terminal is disclosed. The wireless communication terminal includes a transceiver for transmitting and receiving a radio signal; and a processor for controlling the operation of the wireless communication terminal. The transceiver unit receives a trigger frame including information on a channel to be used in communication with a plurality of wireless communication terminals including the wireless communication terminal, which is a base wireless communication terminal that is any one other wireless communication terminal and a plurality of wireless communication terminals. do.

Description

Wireless communication method and wireless communication terminal

The present invention relates to a wireless communication method and a wireless communication terminal for establishing a broadband link. More particularly, it relates to a wireless communication method and a wireless communication terminal for increasing data communication efficiency by extending the data transmission bandwidth of the terminal.

Recently, as the spread of mobile devices has expanded, wireless LAN technology that can provide fast wireless Internet services to them has been in the spotlight. Wireless LAN technology is a technology that enables mobile devices such as smart phones, smart pads, laptop computers, portable multimedia players, and embedded devices to wirelessly access the Internet in a home, business, or specific service area based on wireless communication technology in a short distance. am.

Since IEEE (Institute of Electrical and Electronics Engineers) 802.11 supported the initial wireless LAN technology using the 2.4 GHz frequency, standards for various technologies are being put into practice or being developed. First, IEEE 802.11b supports a communication speed of up to 11Mbps while using a frequency of the 2.4GHz band. IEEE 802.11a, commercialized after IEEE 802.11b, uses a frequency of 5 GHz band instead of 2.4 GHz band, thereby reducing the effect of interference compared to the fairly crowded 2.4 GHz band, and using OFDM technology to maximize communication speed Up to 54 Mbps. However, IEEE 802.11a has a disadvantage in that the communication distance is shorter than that of IEEE 802.11b. Also, IEEE 802.11g, like IEEE 802.11b, uses a frequency of the 2.4GHz band to achieve a communication speed of up to 54Mbps and has received considerable attention as it satisfies backward compatibility. have the upper hand

In addition, IEEE 802.11n is a technical standard established to overcome the limit on communication speed, which has been pointed out as a weakness in wireless LAN. IEEE 802.11n aims to increase the speed and reliability of the network and extend the operating distance of the wireless network. More specifically, IEEE 802.11n supports high throughput (HT) with a data processing rate of up to 540 Mbps or higher, and uses multiple antennas at both ends of the transmitter and receiver to minimize transmission errors and optimize data rates. It is based on MIMO (Multiple Inputs and Multiple Outputs) technology. In addition, this standard may use a coding method that transmits multiple duplicate copies to increase data reliability.

As the spread of wireless LAN is activated and applications using it are diversified, the need for a new wireless LAN system to support a very high throughput (VHT) higher than the data processing speed supported by IEEE 802.11n has emerged. became Among them, IEEE 802.11ac supports a wide bandwidth (80 MHz to 160 MHz) at a frequency of 5 GHz. The IEEE 802.11ac standard is defined only in the 5GHz band, but for backward compatibility with the existing 2.4GHz band products, the initial 11ac chipsets will also support operation in the 2.4GHz band. Theoretically, according to this standard, the wireless LAN speed of multiple stations is at least 1 Gbps, and the maximum single link speed is at least 500 Mbps. This is achieved by extending the air interface concepts adopted by 802.11n, including wider radio frequency bandwidth (up to 160 MHz), more MIMO spatial streams (up to 8), multi-user MIMO, and high-density modulation (up to 256 QAM). In addition, there is IEEE 802.11ad as a method of transmitting data using the 60GHz band instead of the existing 2.4GHz/5GHz. IEEE 802.11ad is a transmission standard that provides a speed of up to 7 Gbps using beamforming technology, and is suitable for streaming large amounts of data or high bit rate video such as uncompressed HD video. However, the 60 GHz frequency band has a disadvantage that it is difficult to pass through obstacles and can only be used between devices in a short distance.

Meanwhile, in recent years, as a next-generation wireless LAN standard after 802.11ac and 802.11ad, discussions have been ongoing to provide a high-efficiency and high-performance wireless LAN communication technology in a high-density environment. That is, in the next-generation wireless LAN environment, high-frequency-efficiency communication must be provided indoors and outdoors in the presence of high-density stations and access points (APs), and various technologies are required to implement it.

In particular, as the number of devices using a wireless LAN increases, it is necessary to efficiently use a predetermined channel. Therefore, there is a need for a technology capable of efficiently using a bandwidth by simultaneously transmitting data between a plurality of stations and an AP.

An embodiment of the present invention aims to provide an efficient wireless communication method and a wireless communication terminal.

In particular, an embodiment of the present invention aims to provide a wireless communication method and a wireless communication terminal that enable an access point to simultaneously transmit data to a plurality of stations and a plurality of stations to simultaneously transmit data to an access point do.

A wireless communication terminal according to an embodiment of the present invention includes a transceiver for transmitting and receiving a radio signal; and a processor for controlling the operation of the wireless communication terminal, wherein the transceiver is a base wireless communication terminal in which a plurality of wireless communication terminals including the wireless communication terminal are different from the plurality of wireless communication terminals. Receives a trigger frame including information about a channel to be used in communication with

The processor acquires information about a channel to be used for communication with the base wireless communication terminal based on the trigger frame, and the transceiver unit is based on the information about a channel to be used for communication with the wireless communication terminal based on the base wireless communication Data can be transmitted to the terminal.

The transceiver may transmit to the base wireless communication terminal a frame indicating whether the wireless communication terminal has data to transmit to the base wireless communication terminal.

The more data field included in the frame indicating whether there is data to be transmitted may indicate whether the wireless communication terminal has data to transmit to the base wireless communication terminal.

The frame indicating whether there is data to be transmitted includes an ACK (Acknowledgment) frame indicating that a frame has been normally received, a block ACK frame indicating that a plurality of frames have been normally received, and uplink data transmitted by the wireless communication terminal to the base wireless communication terminal It may be at least any one of frames including

The frame indicating whether there is data to be transmitted may include at least one of a size of data to be transmitted to the base wireless communication terminal and information about an available channel detected by the wireless communication terminal.

The processor acquires information about a channel to be used for communication with the base wireless communication terminal based on the trigger frame, and the transceiver unit is based on the information about a channel to be used for communication with the wireless communication terminal based on the base wireless communication Data may be received from the terminal.

The transceiver receives a Ready To Send (RTS)-to-Self frame from the base wireless communication terminal, and transmits a Clear To Send (CTS) frame informing the base wireless communication terminal that reception is ready, and the RTS-to -Self frame may be a wireless communication terminal that transmits the RTS frame in the reception address field of a Ready To Send (RTS) frame indicating that there is data to be transmitted.

A transmission time (data airtime) of data received from the base wireless communication terminal may be synchronized with a transmission time of data transmitted to the wireless communication terminal and another wireless communication terminal.

The trigger frame is information about a channel having a bandwidth greater than or equal to the minimum unit frequency bandwidth that the base wireless communication terminal can use in communication and a sub-band of the channel, and is a sub-channel having a bandwidth less than or equal to the minimum unit frequency bandwidth. It may contain information about

The information on the channel may be an index indicating the channel, and the information on the sub-channel may be an index indicating the sub-channel.

Base wireless communication terminal according to an embodiment of the present invention includes a transceiver for transmitting and receiving a radio signal; and a processor for controlling the operation of the wireless communication terminal, wherein the processor allocates a channel to be used in communication with the base wireless communication terminal to a plurality of wireless communication terminals, It transmits a trigger frame including information about the plurality of wireless communication terminals.

The transceiver may receive data from a second wireless communication terminal, which is one of the plurality of wireless communication terminals, through a channel allocated to the second wireless communication terminal.

The transceiver may receive a frame indicating that there is data to be transmitted from the second wireless communication terminal to the base wireless communication terminal by the second wireless communication terminal, and transmit the trigger frame based on the received frame.

The more data field included in the frame indicating whether there is data to be transmitted may indicate whether the second wireless communication terminal has data to transmit to the base wireless communication terminal.

The frame indicating whether there is data to be transmitted includes an ACK (Acknowledgment) frame indicating that a frame has been normally received, a block ACK frame indicating that a plurality of frames have been normally received, and uplink data transmitted from the wireless communication terminal to the base wireless communication terminal It may be at least any one of frames including

The frame indicating whether there is data to be transmitted may include at least one of a size of data to be received from the second wireless communication terminal and information about an available channel detected by the second wireless communication terminal.

The processor may allocate a channel to be used for communication with the plurality of wireless communication terminals to the plurality of wireless communication terminals based on a frame indicating whether there is data to be transmitted.

The information on the channel may be an index indicating the channel, and the information on the sub-channel may be an index indicating the sub-channel.

In the method of operating a wireless communication terminal according to an embodiment of the present invention, a plurality of wireless communication terminals including the wireless communication terminal communicate with a base wireless communication terminal that is any one other wireless communication terminal from a plurality of wireless communication terminals. Receiving a trigger frame including information on a channel to be used; and transmitting data to the base wireless communication terminal or receiving data from the base wireless communication terminal based on the information on the channel.

An embodiment of the present invention provides an efficient wireless communication method and a wireless communication terminal.

In particular, an embodiment of the present invention provides a wireless communication method and a wireless communication terminal that enable an access point to simultaneously transmit data to a plurality of stations and a plurality of stations to simultaneously transmit data to an access point.

1 shows a wireless LAN system according to an embodiment of the present invention.
2 shows a wireless LAN system according to another embodiment of the present invention.
3 is a block diagram showing the configuration of a station according to an embodiment of the present invention.
4 is a block diagram showing the configuration of an access point according to an embodiment of the present invention.
5 schematically shows a process in which a station establishes a link with an access point according to an embodiment of the present invention.
6 shows the structure of a pole frame according to an embodiment of the present invention.
7 shows the structure of a pole frame according to another embodiment of the present invention.
8 shows the structure of a CH vector field of a poll frame according to an embodiment of the present invention.
9 shows a channel index of a 5 GHz frequency band according to an embodiment of the present invention.
10 shows a channel index of a 5 GHz frequency band according to another embodiment of the present invention.
11 shows a sub-channel index in a frequency band of 20 MHz according to an embodiment of the present invention.
12 shows a sub-channel index in a frequency band of 20 MHz according to another embodiment of the present invention.
13 shows a sub-channel index in a frequency band of 20 MHz including a combination between non-adjacent sub-bands according to another embodiment of the present invention.
14 shows a preamble including sub-channel information according to an embodiment of the present invention.
15 shows a preamble including sub-channel information according to another embodiment of the present invention.
16 shows a preamble including sub-channel information according to another embodiment of the present invention.
17 shows a preamble including sub-channel information according to another embodiment of the present invention.
18 shows a CH vector field indicating a combination of non-adjacent sub-band channels according to another embodiment of the present invention.
19 shows the structure of an RTS-to-Self frame according to an embodiment of the present invention.
20 shows that an access point simultaneously transmits data to a plurality of stations using an RTS-to-Self frame according to an embodiment of the present invention.
21 shows that an access point simultaneously transmits data to a plurality of stations using an RTS-to-Self frame according to another embodiment of the present invention.
22 shows that the access point allocates one channel to each of a plurality of stations and asynchronously transmits data to the plurality of stations according to an embodiment of the present invention.
23 shows that the access point allocates one or more channels to each of a plurality of stations and asynchronously transmits data to the plurality of stations according to an embodiment of the present invention.
24 shows that the access point allocates one channel to each of a plurality of stations and synchronously transmits data to the plurality of stations according to an embodiment of the present invention.
25 shows that the access point allocates one or more channels to each of a plurality of stations and synchronously transmits data to the plurality of stations according to an embodiment of the present invention.
26 shows that the access point transmits data to a plurality of stations when it does not receive a CTS frame from any one station according to an embodiment of the present invention.
27 illustrates an operation in which the access point simultaneously transmits data to a plurality of stations when the access point cannot simultaneously receive data from a plurality of stations according to another embodiment of the present invention.
28 is a diagram illustrating a case in which an access point transmits data to a plurality of stations after PIFS from when the access point transmits a poll frame to a plurality of stations according to an embodiment of the present invention shows the transmission of
29 shows that an access point transmits a poll frame to a plurality of stations, transmits an RTS-to-Self frame, and then transmits data according to an embodiment of the present invention.
30 shows that an access point transmits data to a plurality of stations using M-RTS according to an embodiment of the present invention.
31 shows that a plurality of stations transmit data to an access point after receiving data from the access point according to an embodiment of the present invention.
32 shows that each of a plurality of stations transmits data to an access point through a channel used when the access point transmits data to each of the plurality of stations according to an embodiment of the present invention.
33 shows that a plurality of stations transmit data to an access point by receiving a channel allocation regardless of whether the access point uses a corresponding channel when transmitting data to the plurality of stations according to an embodiment of the present invention.
34 is a diagram illustrating an access point allocating a channel to a plurality of stations based on information about an available channel transmitted by the station, and transmitting data to the access point according to the channel assigned to the plurality of stations according to an embodiment of the present invention show what to do
35 shows that an access point secures a TXOP through a contention procedure and a CTS-to-Self frame, and a plurality of stations transmit data to the access point according to an embodiment of the present invention.
36 is a diagram illustrating data transmission between an access point and a plurality of stations when some stations among a plurality of stations have no data to transmit to the access point according to an embodiment of the present invention.
37 shows data transmission between the access point and the plurality of stations when there is no data to be transmitted from the plurality of stations to the access point according to an embodiment of the present invention.
38 shows that an access point transmits a trigger frame to a plurality of stations according to another embodiment of the present invention.
39 shows the structure of a frame indicating whether a station has data to transmit to an access point according to another embodiment of the present invention.
40 shows that a plurality of stations notifies an access point of whether there is data to be transmitted through an ACK frame according to another embodiment of the present invention.
41 shows that a plurality of stations notifies an access point of whether there is data to be transmitted through an uplink transmission data frame according to another embodiment of the present invention.
42 is a ladder diagram illustrating an operation in which a first wireless communication terminal transmits data to a second wireless communication terminal according to an embodiment of the present invention.
43 is a ladder diagram illustrating an operation in which a second wireless communication terminal transmits data to a first wireless communication terminal according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

In addition, when a part "includes" a certain component, this means that other components may be further included, rather than excluding other components, unless otherwise stated.

This application is the Republic of Korea Patent Application Nos. 10-2014-0101776, 10-2014-0109433, 10-2014-0114610, 10-2014-0143125, 10-2015-0035127, and 10- Priority is claimed based on No. 2015-0066669, and the embodiments and descriptions described in each of the above applications, which are the basis of the priority, are included in the detailed description of the present application.

1 illustrates a wireless LAN system according to an embodiment of the present invention. The WLAN system includes one or more basic service sets (BSS), which indicate a set of devices that can communicate with each other by successfully synchronizing. In general, the BSS may be divided into an infrastructure BSS (infrastructure BSS) and an independent BSS (IBSS), and FIG. 1 shows the infrastructure BSS among them.

As shown in FIG. 1 , the infrastructure BSS (BSS1, BSS2) includes one or more stations (STA1, STA2, STA3, STA4, STA5) and an access point (PCP/AP) that is a station providing a distribution service. -1, PCP/AP-2), and a Distribution System (DS) connecting a plurality of access points (PCP/AP-1, PCP/AP-2).

A station (Station, STA) is an arbitrary device including a medium access control (MAC) and a physical layer interface for a wireless medium that comply with the provisions of the IEEE 802.11 standard, and in a broad sense, a non-access point ( It includes both non-AP) stations as well as access points (APs). Also, in this specification, the term 'terminal' may be used as a concept including both a station and a wireless LAN communication device such as an AP. The station for wireless communication includes a processor and a transmit/receive unit, and may further include a user interface unit and a display unit according to an embodiment. The processor may generate a frame to be transmitted through the wireless network or process a frame received through the wireless network, and may perform various other processes for controlling the station. In addition, the transceiver is functionally connected to the processor and transmits and receives frames through a wireless network for the station.

An access point (AP) is an entity that provides access to a distribution system (DS) via a wireless medium for a station associated with it. In the infrastructure BSS, in principle, communication between non-AP stations is performed via the AP, but when a direct link is established, direct communication is also possible between non-AP stations. Meanwhile, in the present invention, the AP is used as a concept including a PCP (Personal BSS Coordination Point), and broadly, a centralized controller, a base station (BS), a Node-B, a BTS (Base Transceiver System), or a site. It may include all concepts such as a controller.

A plurality of infrastructure BSSs may be interconnected through a distribution system (DS). In this case, a plurality of BSSs connected through the distribution system are referred to as an extended service set (ESS).

2 illustrates an independent BSS as a wireless LAN system according to another embodiment of the present invention. In the embodiment of Fig. 2, the same or corresponding parts to the embodiment of Fig. 1 will be omitted redundant description.

Since BSS3 shown in FIG. 2 is an independent BSS and does not include an AP, all stations STA6 and STA7 are not connected to the AP. The independent BSS is not allowed to access the distribution system and forms a self-contained network. In the independent BSS, each of the stations STA6 and STA7 may be directly connected to each other.

* FIG. 3 is a block diagram showing the configuration of the station 100 according to an embodiment of the present invention.

As shown, the station 100 according to an embodiment of the present invention may include a processor 110 , a transceiver 120 , a user interface unit 140 , a display unit 150 , and a memory 160 . .

First, the transceiver 120 transmits/receives wireless signals such as wireless LAN packets, and may be built-in or externally provided in the station 100 . According to an embodiment, the transceiver 120 may include at least one transceiver module using different frequency bands. For example, the transceiver 120 may include transceiver modules of different frequency bands, such as 2.4 GHz, 5 GHz, and 60 GHz. According to an embodiment, the station 100 may include a transmission/reception module using a frequency band of 6 GHz or higher and a transmission/reception module using a frequency band of 6 GHz or less. Each transmission/reception module may perform wireless communication with an AP or an external station according to a wireless LAN standard of a frequency band supported by the transmission/reception module. The transceiver 120 may operate only one transceiver module at a time or operate a plurality of transceiver modules simultaneously according to the performance and requirements of the station 100 . When the station 100 includes a plurality of transmit/receive modules, each transmit/receive module may be provided in an independent form, or a plurality of modules may be integrated into one chip.

Next, the user interface unit 140 includes various types of input/output means provided in the station 100 . That is, the user interface unit 140 may receive a user input using various input means, and the processor 110 may control the station 100 based on the received user input. Also, the user interface unit 140 may perform an output based on a command of the processor 110 using various output means.

Next, the display unit 150 outputs an image on the display screen. The display unit 150 may output various display objects such as content executed by the processor 110 or a user interface based on a control command of the processor 110 . In addition, the memory 160 stores a control program used in the station 100 and various data corresponding thereto. Such a control program may include an access program necessary for the station 100 to access an AP or an external station.

The processor 110 of the present invention may execute various commands or programs and process data inside the station 100 . In addition, the processor 110 may control each unit of the above-described station 100 , and may control data transmission/reception between the units. According to an embodiment of the present invention, the processor 110 may execute a program for accessing the AP stored in the memory 160 and receive a communication setting message transmitted by the AP. Also, the processor 110 may read information on the priority condition of the station 100 included in the communication setup message, and request access to the AP based on the information on the priority condition of the station 100 . The processor 110 of the present invention may refer to the main control unit of the station 100, and according to an embodiment, a control unit for individually controlling a part of the station 100, for example, the transceiver 120, etc. may point to The processor 110 controls various operations of wireless signal transmission and reception of the station 100 according to an embodiment of the present invention. Specific examples thereof will be described later.

The station 100 shown in FIG. 3 is a block diagram according to an embodiment of the present invention. Separately indicated blocks are logically separated and illustrated for device elements. Accordingly, the elements of the above-described device may be mounted as one chip or a plurality of chips according to the design of the device. For example, the processor 110 and the transceiver 120 may be integrated into one chip or implemented as a separate chip. In addition, in the embodiment of the present invention, some components of the station 100 , such as the user interface unit 140 and the display unit 150 , may be selectively provided in the station 100 .

4 is a block diagram showing the configuration of the AP 200 according to an embodiment of the present invention.

As shown, the AP 200 according to an embodiment of the present invention may include a processor 210 , a transceiver 220 , and a memory 260 . Among the configurations of the AP 200 in FIG. 4 , redundant descriptions of parts identical to or corresponding to those of the station 100 of FIG. 3 will be omitted.

Referring to FIG. 4 , the AP 200 according to the present invention includes a transceiver 220 for operating a BSS in at least one frequency band. As described above in the embodiment of FIG. 3 , the transceiver 220 of the AP 200 may also include a plurality of transceiver modules using different frequency bands. That is, the AP 200 according to the embodiment of the present invention may include two or more transmission/reception modules in different frequency bands, for example, 2.4 GHz, 5 GHz, and 60 GHz. Preferably, the AP 200 may include a transmission/reception module using a frequency band of 6 GHz or higher and a transmission/reception module using a frequency band of 6 GHz or less. Each transmission/reception module may perform wireless communication with a station according to a wireless LAN standard of a frequency band supported by the corresponding transmission/reception module. The transceiver 220 may operate only one transceiver module at a time or operate a plurality of transceiver modules simultaneously according to the performance and requirements of the AP 200 .

Next, the memory 260 stores a control program used in the AP 200 and various data corresponding thereto. Such a control program may include an access program for managing access of stations. In addition, the processor 210 may control each unit of the AP 200 , and may control data transmission/reception between the units. According to an embodiment of the present invention, the processor 210 may execute a program for connection with a station stored in the memory 260 and transmit a communication setting message for one or more stations. In this case, the communication setting message may include information on the access priority condition of each station. In addition, the processor 210 performs connection establishment according to the connection request of the station. The processor 210 controls various operations of wireless signal transmission and reception of the AP 200 according to an embodiment of the present invention. Specific examples thereof will be described later.

5 schematically illustrates a process in which an STA establishes a link with an AP.

Referring to FIG. 5 , the link between the STA 100 and the AP 200 is largely established through three steps of scanning, authentication, and association. First, the scanning step is a step in which the STA 100 acquires access information of the BSS operated by the AP 200 . As a method for performing scanning, a passive scanning method in which information is obtained by using only a beacon message S101 periodically transmitted by the AP 200, and a probe request by the STA 100 to the AP There is an active scanning method for transmitting a probe request (S103) and receiving a probe response from the AP (S105) to obtain access information.

The STA 100 successfully receiving the radio access information in the scanning step transmits an authentication request (S107a), receives an authentication response from the AP 200 (S107b), and performs the authentication step do. After the authentication step is performed, the STA 100 transmits an association request (S109a) and receives an association response from the AP 200 (S109b) to perform the association step.

Meanwhile, an additional 802.1X-based authentication step (S111) and an IP address acquisition step (S113) through DHCP may be performed. In FIG. 5 , the authentication server 300 is a server that processes 802.1X-based authentication with the STA 100 , and may exist physically coupled to the AP 200 or exist as a separate server.

When data is transmitted using an orthogonal frequency division multiple access (OFDMA), any one wireless communication terminal may simultaneously transmit data to a plurality of wireless communication terminals. In addition, any one wireless communication terminal may simultaneously receive data from a plurality of wireless communication terminals. To this end, a frequency channel is allocated to a plurality of wireless communication terminals communicating with any one wireless communication terminal. Therefore, it is necessary for any one wireless communication terminal to effectively inform the plurality of wireless communication terminals of information on frequency channels allocated to each of the plurality of wireless communication terminals. An embodiment of the present invention in which any one wireless communication terminal effectively signals information of a frequency channel allocated to each of a plurality of wireless communication terminals to a plurality of wireless communication terminals through the drawings and drawings after FIG. 5 do. For convenience of description, any one wireless communication terminal simultaneously communicating with a plurality of wireless communication terminals is referred to as a first wireless communication terminal, and a plurality of wireless communication terminals simultaneously communicating with the first wireless communication terminal are referred to as a plurality of second wireless communication terminals. It is referred to as a communication terminal. In this case, the first wireless communication terminal may be the access point 200 . Also, the second wireless communication terminal may be a station 100 associated with the access point 200 . According to a specific embodiment, the first wireless communication terminal may be referred to as a base wireless communication terminal.

In addition, the first wireless communication terminal allocates a communication medium resource in communication with a plurality of wireless communication terminals and performs the role of a cell coordinator for scheduling (scheduling) It may be a wireless communication terminal. .

In a specific embodiment, the first wireless communication terminal may be a wireless communication terminal that allocates communication medium resources and performs scheduling in an independent network that is not connected to an external distribution service, such as an ad-hoc network.

Also, the first wireless communication terminal may be at least one of a base station, an eNB, and a transmission point (TP). A frame including information on a frequency channel allocated to each communication terminal will be described. A frame including information on a frequency channel allocated to each of the plurality of second wireless communication terminals is referred to as a poll frame. According to a specific embodiment, the poll frame may be referred to as a trigger frame. In a specific embodiment, the first wireless communication terminal may transmit a poll frame to the second wireless communication terminal to inform the second wireless communication terminal of information on the assigned frequency channel. In addition, after transmitting the poll frame, the first wireless communication terminal may simultaneously transmit data to a plurality of second wireless communication terminals through a channel allocated to each of the plurality of second wireless communication terminals. In addition, after receiving the poll frame, the second wireless communication terminal may transmit data to the first wireless communication terminal simultaneously with another second wireless communication terminal.

6 shows the structure of a pole frame according to an embodiment of the present invention.

The poll frame may include a Basic Service Set Identifier (BSSID) that identifies the basic service set to which the poll frame is transmitted. In this case, the BSSID may indicate the MAC address of the first wireless communication terminal transmitting the poll frame.

The poll frame may include source address information indicating the address of the first wireless communication terminal that transmits the poll frame. In this case, the address of the first wireless communication terminal may be the MAC address of the first wireless communication terminal. The same BSSID and source address information may be used as information indicating the first wireless communication terminal. Therefore, according to a specific embodiment, the poll frame may include only one of BSSID and source address information.

The poll frame may include length information indicating the length of the poll frame. The second wireless communication terminal may acquire the number of second wireless communication terminals participating in data transmission based on the length information. Specifically, the second wireless communication terminal obtains a variable length by subtracting the length of the field of the fixed poll frame from the length of the poll frame indicated by the length information, regardless of the number of second wireless communication terminals participating in data transmission. Thereafter, the second wireless communication terminal may obtain the number of second wireless communication terminals participating in data transmission by dividing the obtained variable length by the length of a variable field required for one second wireless communication terminal.

The poll frame may include channel vector information indicating information on a frequency channel allocated to the second wireless communication terminal. The channel vector information may include a frequency channel allocated to the second wireless communication terminal. In addition, the channel vector information may include destination address information indicating the address of the second wireless communication terminal to which the corresponding channel is allocated. In this case, the information indicating the address of the second wireless communication terminal may be an Association Identifier (AID) for identifying an association between the first wireless communication terminal and the second wireless communication terminal. The second wireless communication terminal may recognize a channel assigned to it based on the channel vector information, and receive data from the first wireless communication terminal through the corresponding channel. In addition, the second wireless communication terminal may recognize the channel allocated to it based on the channel vector information, and transmit data to the first wireless communication terminal through the corresponding channel. A detailed format of the channel vector information will be described later with reference to FIGS. 8 to 17 .

In a specific embodiment, the pole frame may have the same structure as in the embodiment of FIG. 6 . Specifically, the poll frame may include a frame control field indicating control information of the frame. The poll frame may include a BSSID field indicating the BSSID. The poll frame may include a Source Address (SA) field indicating source address information. The poll frame may include a Length field indicating length information. The poll frame may include a CH vector field indicating channel vector information. The poll frame may include an STA ID field indicating the address of the second wireless communication terminal to which the channel indicated by the CH vector field is allocated. The poll frame may include an FCS field including a cyclical redundancy check (CRC) value for error detection.

7 shows the structure of a pole frame according to another embodiment of the present invention.

The poll frame may include duration information indicating a time required for data transmission after transmission of the poll frame. Through this, it is possible to prevent other wireless communication terminals from accessing a frequency channel used for data transmission before data transmission is terminated.

In addition, the poll frame may include information indicating the number of second wireless communication terminals to which the poll frame allocates a frequency channel.

In a specific embodiment, the pole frame may have the same structure as in the embodiment of FIG. 7 . Specifically, the poll frame may include a duration field indicating duration information. Also, according to a specific situation, the duration field may indicate the number of second wireless communication terminals to which the poll frame allocates a frequency channel. Also, according to specific circumstances, the duration field may indicate length information of a poll frame.

As described above, when the first wireless communication terminal and the plurality of second wireless communication terminals communicate using OFDMA, the plurality of second wireless communication terminals are notified of the channel information assigned to each of the plurality of second wireless communication terminals. There is a need. To this end, the poll frame may include channel vector information indicating information on a frequency channel allocated to the second wireless communication terminal. Such channel vector information may be used to indicate information of a channel allocated to the second wireless communication terminal even in a frame other than the poll frame or in a preamble of a signal including a frame. An embodiment in which a specific format of channel vector information and channel vector information is used will be described with reference to FIGS. 8 to 17 .

8 shows the structure of a CH vector field of a poll frame according to an embodiment of the present invention.

As OFDMA transmission becomes possible, a plurality of second wireless communication terminals according to an embodiment of the present invention divides the minimum unit frequency bandwidth that the first wireless communication terminal can use during communication, and uses each of the divided bandwidths to simultaneously perform 1 Can communicate with a wireless communication terminal. In this case, the minimum unit frequency bandwidth may be 20 MHz. Accordingly, the channel vector information may include sub-channel information as well as channel information. In this case, the channel information is information about a channel having a bandwidth equal to or greater than the minimum unit frequency bandwidth. In addition, the sub-channel information is information about a sub-channel having a bandwidth less than or equal to the minimum unit frequency bandwidth as a sub-band included in the channel. In this case, the channel use pattern usable by the first wireless communication terminal and the second wireless communication terminal may be predefined. In this case, channels other than the predetermined channel use pattern cannot be used. In this case, the channel usage pattern may indicate the range of the frequency band and whether the frequency band is combined. These channel usage patterns can be set in various regulations and technical realization possibilities. Also, such a channel usage pattern may be expressed as an index. Accordingly, the channel vector information may include index information indicating a channel usage pattern. Specifically, it may include channel index information indicating a channel. And the channel vector information may include sub-channel index information indicating the sub-channel.

In addition, in order to prevent the size of the poll frame from increasing due to the excessively large size of the channel vector information, the channel vector information may include only channel allocation information for a predetermined number of second wireless communication terminals. Specifically, when it is necessary to transmit channel allocation information for a predetermined number or more of the second wireless communication terminals, the first wireless communication terminal may divide the channel allocation information for a plurality of second wireless communication terminals into a plurality of poll frames and transmit.

In addition, in order to prevent the size of the poll frame from becoming too large due to the excessive increase in the size of the channel vector information, the channel vector information is provided in a group unit of a second wireless communication terminal including a plurality of second wireless communication terminals, not in units of the second wireless communication terminal may include channel information. Specifically, the channel vector information may include a group identifier for identifying the group of the second wireless communication terminal and channel information allocated to the group of the second wireless communication terminal. In this case, the first wireless communication terminal may manage the group identifier. Specifically, the first wireless communication terminal may assign a group identifier to the plurality of second wireless communication terminals in an association or re-association process. In this case, the first wireless communication terminal may allocate to the second wireless communication terminal up to a reserved group identifier left for future use. In addition, the maximum number of group identifiers that can be allocated by the first wireless communication terminal may be limited to a certain number. When the channel vector information includes the channel allocation information on a group basis of the second wireless communication terminal, the first wireless communication terminal converts the channel information allocated to each of the second wireless communication terminals included in the group to the channel vector in the preamble of the data. information can be communicated.

In a specific embodiment, the channel vector information includes information identifying the second wireless communication terminal and channel information allocated to the second wireless communication terminal. In this case, the channel information may include channel index information and sub-channel index information as described above. Specifically, the channel information may be a 2-byte field as in the embodiment of FIG. 8 . In addition, the channel vector information may indicate channel index information through 12 bits and sub-channel index information through 4 bits. When the first wireless communication terminal uses a frequency band in which a plurality of minimum unit frequency bands are combined, a field indicating such sub-channel index information may not be used. Specifically, when the size of the minimum unit frequency band is 20 MHz and the first wireless communication terminal uses a frequency band greater than 20 MHz, the first wireless communication terminal and the second wireless communication terminal do not use sub-channel index information. may not be In addition, some of the 12 bits indicating the above-described channel index information may be left as reserve bits in preparation for a change in the format of the channel vector information later.

As described above, the poll frame may include a duration field indicating duration information. Also, according to a specific situation, the duration field may indicate the number of second wireless communication terminals to which the poll frame allocates a frequency channel. Also, according to a specific situation, the duration field may be information indicating the number of second wireless communication terminals to which a poll frame allocates a channel. In this case, the second wireless communication terminal may determine the length of the poll frame based on the duration field. This is because the length of the poll frame becomes longer as the number of second wireless communication terminals to which the poll frame allocates channels increases.

9 shows a channel index of a 5 GHz frequency band according to an embodiment of the present invention, and FIG. 10 shows a channel index of a 5 GHz frequency band according to another embodiment of the present invention.

When the first wireless communication terminal uses only a combination of contiguous frequency bands, a channel index as in the embodiment of FIG. 9 may be used. In this case, the number of adjacent frequency channels is 256 or less. Accordingly, a field for indicating channel index information in the channel vector information may be a field of 8 bits or less.

In a specific embodiment, the first wireless communication terminal and the second wireless communication terminal may use a combination of non-contiguous frequency bands. In this case, the same channel index as in the embodiment of FIG. 10 may be used. For example, the channel index 800 of FIG. 10C represents a frequency band in which the frequency bands respectively indicated by the non-adjacent channel index 4 and the channel index 24 are combined. In this case, the number of possible channels may be 256 or more. In this case, a field for indicating channel index information in the channel vector information may be a field of 8 bits or more. Specifically, the sum of the size of the field indicating the channel index information and the size of the field indicating the sub-channel index information may be 16 bits. Specifically, a field for indicating channel index information may be a 12-bit field. In addition, the first wireless communication terminal and the second wireless communication terminal may use a bandwidth other than 1, 2, 4, or 8 times the minimum unit frequency bandwidth. For example, in the embodiment of FIG. 10 ( b ) having a minimum unit frequency bandwidth of 20 MHz, the frequency band indicated by the channel index 240 has a 100 MHz bandwidth that is 5 times the minimum unit frequency bandwidth of 20 MHz. In addition, the first wireless communication terminal and the second wireless communication terminal may use a frequency band that is adjacent to the existing 802.11ac but not simultaneously utilized. For example, the channel index 75 of FIG. 10 (a) represents a frequency band in which the channel index 10 and the frequency bands respectively indicated by the channel index 75 are combined.

As described above, the channel vector information may include sub-channel index information. In this case, the sub-channel index information may indicate allocation of a sub-channel or a sub-carrier. In addition, the channel vector information including the sub-channel index information may be included in a preamble of a communication signal between the first wireless communication terminal and the second wireless communication terminal as well as the poll frame. Such sub-channel index information will be described with reference to FIGS. 11 to 18 .

11 shows a sub-channel index in a frequency band of 20 MHz according to an embodiment of the present invention.

In a specific embodiment, the first wireless communication terminal and the second wireless communication terminal may divide and use a frequency band having a minimum unit frequency bandwidth into eight sub-bands. In this case, the first wireless communication terminal and the second wireless communication terminal may use a combination of 8 sub-bands as sub-channels. The minimum unit frequency bandwidth may be 20 MHz. The first wireless communication terminal and the second wireless communication terminal may use 15 sub-channels as shown in FIG. 11 by combining 8 sub-bands with adjacent sub-bands. In addition, when the first wireless communication terminal and the second wireless communication terminal display channel vector information using the group identifier, the sub-channel index is included in the corresponding group, but the second wireless communication terminal is not assigned a sub-channel. case should be indicated. Therefore, the number of cases that the sub-channel index must represent is 16 in total. Therefore, the sub-channel index can be represented by a 4-bit field.

12 shows a sub-channel index in a frequency band of 20 MHz according to another embodiment of the present invention.

In a specific embodiment, the first wireless communication terminal and the second wireless communication terminal may divide and use a frequency band having a minimum unit frequency bandwidth into nine sub-bands. The minimum unit frequency bandwidth may be 20 MHz. The first wireless communication terminal and the second wireless communication terminal may use 15 sub-channels as shown in FIG. 12 by combining 8 sub-bands except for the fifth frequency sub-band with adjacent sub-bands. Except for the case of using all the minimum unit frequency bands, if the channel vector information is indicated using the group identifier and including the case, the total number of sub-channels is 15. In addition, the sub-channel index should indicate a case in which the second wireless communication terminal is not allocated a sub-channel although it is included in the corresponding group. Therefore, the total number of cases that the sub-channel index should indicate is 16. Therefore, the sub-channel index can be represented by a 4-bit field.

13 shows a sub-channel index in a frequency band of 20 MHz including a combination between non-adjacent sub-bands according to another embodiment of the present invention.

In a specific embodiment, the first wireless communication terminal and the second wireless communication terminal may divide and use a frequency band having a minimum unit frequency bandwidth into nine sub-bands. The minimum unit frequency bandwidth may be 20 MHz. The first wireless communication terminal and the second wireless communication terminal may combine the nine sub-bands without constraint conditions and use them as sub-channels. Specifically, the first wireless communication terminal and the second wireless communication terminal may combine non-adjacent sub-bands and use them as one sub-channel. For example, in FIG. 13 , sub-channel index 17 indicates a frequency band in which the frequency bands indicated by sub-channel index 1, sub-channel index 2, and sub-channel index 5 are combined. In this case, since there are 16 or more cases in which the sub-channel index should be indicated, the sub-channel index may be represented by a field of 5 bits or more.

The preamble of the signal transmitted from the first wireless communication terminal to the second wireless communication terminal may include sub-channel or sub-carrier allocation information. In a specific embodiment, the preamble of the signal transmitted from the first wireless communication terminal to the second wireless communication terminal may include sub-channel index information. Through this, the second wireless communication terminal may decode the preamble signal transmitted from the first wireless communication terminal to obtain information about the sub-channel allocated to it. In a specific embodiment, the preamble of the signal transmitted from the first wireless communication terminal to the second wireless communication terminal may include sub-channel index information in at least one of SIG-A, SIG-B, and SIG-C. A specific format of sub-channel information included in the preamble of a signal transmitted from the first wireless communication terminal to the second wireless communication terminal will be described with reference to FIGS. 14 to 18 .

14 shows a preamble including sub-channel information according to an embodiment of the present invention.

As described above, the channel vector information included in the poll frame may include channel allocation information in units of groups of second wireless communication terminals including a plurality of second wireless communication terminals, rather than in units of second wireless communication terminals. In this case, the sub-channel information included in the preamble of the signal transmitted from the first wireless communication terminal to the second wireless communication terminal may include a group identifier of a group including the second wireless communication terminal to which the sub-channel is allocated. .

In addition, the sub-channel information may include information indicating a sub-channel allocated to the second wireless communication terminal. In this case, the information indicating the sub-channel may be a sub-channel index indicating the sub-channel.

In a specific embodiment, the format of sub-channel information included in the preamble may be as shown in FIG. 14 . Specifically, the sub-channel information may include a Group ID field indicating a group identifier. In a specific embodiment, the Group ID field may be 6 bits or a field of 6 bits or more. For example, when the maximum number of second wireless communication terminals that can access one first wireless communication terminal is 4, the Group ID field may be a 6-bit field. In addition, when the maximum number of second wireless communication terminals that can access one first wireless communication terminal is 4 or more, the Group ID field may be a field of 6 bits or more.

In addition, the sub-channel information may include a CH vector field indicating a sub-channel allocated to the second wireless communication terminal. In a specific embodiment, the CH vector field may indicate that a subchannel is not allocated to the second wireless communication terminal corresponding to the corresponding CH vector field. In this case, the value of the CH vector field corresponding to the second wireless communication terminal that does not participate in the transmission with the first wireless communication may be 0. In a specific embodiment, the CH vector field may be a 4-bit field. Currently, MU-MIMO (Multi User- Multi Input and Multi Output) allows simultaneous access of a total of four wireless communication terminals to the first wireless communication terminal. Accordingly, the sub-channel information may include 4 CH vector fields. In addition, when the number of second wireless communication terminals capable of simultaneously accessing the first wireless communication terminal allowed by MU-MIMO increases, the number of CH vector fields may be increased.

In addition, the order of the second wireless communication terminal corresponding to the CH vector field may follow the order of the second wireless communication terminal identifier of the channel vector information included in the above-described poll frame. Accordingly, the second wireless communication terminal may acquire sub-channel information corresponding to the second wireless communication terminal based on the order of the second wireless communication terminal identifier of the channel vector information included in the poll frame.

15 shows a preamble including sub-channel information according to another embodiment of the present invention.

In case the number of second wireless communication terminals capable of simultaneously accessing one first wireless communication terminal increases, the number of CH vector fields may not be limited as in FIG. 15 .

16 shows a preamble including sub-channel information according to another embodiment of the present invention.

As described with reference to FIG. 15, when the number of CH vector fields is not limited, the second wireless communication terminal has a problem in that it has to continuously decode the variable signal without knowing the number of CH vector fields. In order to solve this problem, the sub-channel information of the preamble included in the signal transmitted from the first wireless communication terminal to the second wireless communication terminal may include information indicating the number of the second wireless communication terminals to which the sub-channel is allocated. . In another specific embodiment, when one second wireless communication terminal is allocated per one sub-channel, the sub-channel information may include the number of allocated sub-channels.

In a specific embodiment, the sub-channel information may include a Number of User field indicating the number of second wireless communication terminals to which the sub-channel is allocated as in the embodiment of FIG. 16 . In this case, the Number of User field may be a 4-bit field.

In another specific embodiment, the sub-channel information may include a channel divide factor field indicating the number of allocated sub-channels as in the embodiment of FIG. 16 . In this case, the channel divide factor field may be a 4-bit field.

Through this embodiment, the second wireless communication terminal can accurately know the size of the preamble to be decoded.

17 shows a preamble including sub-channel information according to another embodiment of the present invention.

According to the above-described embodiment, the second wireless communication terminal must determine whether to allocate sub-channels by decoding all sub-channel information even when sub-channels are not allocated. To prevent this, the sub-channel information included in the preamble of the signal transmitted from the first wireless communication terminal to the second wireless communication terminal may include information indicating whether OFDMA communication using the sub-channel is used.

In a specific embodiment, the sub-channel information may include an OFDMA Indication field indicating whether OFDMA communication using a sub-channel is used as in the embodiment of FIG. 17 . In a specific embodiment, the OFDMA Indication field may be a 1-bit flag. For example, when the value of the OFDMA Indication field is 1, the OFDMA Indication field may indicate that the first wireless communication terminal allocates the sub-channel to the second wireless communication terminal for OFDMA communication using the sub-channel.

When the OFDMA Indication field is a 1-bit flag, the above-described Number of User field may be a 3-bit field. In addition, when the value indicated by the Number of User field is N, it may indicate that a sub-channel is allocated to the second wireless communication terminal of N-2. Indicating that the sub-channel is allocated to the second wireless communication terminal of N-2 instead of N is because the sub-channel is allocated to two or more second wireless communication terminals when OFDMA communication using the sub-channel is used.

18 shows a CH vector field indicating a combination of non-adjacent sub-band channels according to another embodiment of the present invention.

In the specific embodiment described above, it has been described that the CH vector field included in the sub-channel information may be 4 bits. However, since the number of sub-channels increases when sub-channels indicating non-consecutive combinations of sub-bands are supported, the CH vector field may be a field of 5 bits or more.

In a specific embodiment, the channel vector information may indicate that the second wireless communication terminal can randomly access within a certain channel range. In this case, the second wireless communication terminal may randomly attempt access within a designated channel range. If the second wireless communication terminal fails to transmit due to a collision with another wireless communication terminal during random access, it may try to access again.

Signaling of frequency channel information allocated to each of a plurality of second wireless communication terminals for OFDMA communication between a first wireless communication terminal and a plurality of second wireless communication terminals has been described with reference to FIGS. 6 to 18 . It will be described that a first wireless communication terminal simultaneously transmits data to a plurality of second wireless communication terminals with reference to FIGS. 19 to 30 .

When the wireless communication terminal performs one-to-one communication, the wireless communication terminal uses a Ready To Send (RTS) frame indicating that it is ready to transmit and a Clear To Send (CTS) frame that indicates that it is ready to receive a Transmit Opportunity. ; TXOP) is guaranteed. However, since the existing RTS frame and the CTS frame are for one-to-one communication, a wireless communication terminal transmitting data and a wireless communication terminal receiving data are limited to one. Therefore, there is a need for a new TXOP securing method for a case in which one wireless communication terminal simultaneously transmits data to a plurality of wireless communication terminals using OFDMA. This will be described with reference to FIGS. 19 to 29 .

19 shows the structure of an RTS-to-Self frame according to an embodiment of the present invention.

The first wireless communication terminal may transmit a frame for informing the plurality of second wireless communication terminals that transmission to the plurality of second wireless communication terminals is started. In this case, the frame for notifying that transmission to the plurality of second wireless communication terminals is started may be used by modifying the RTS frame.

The RTS frame includes a frame control field indicating frame control information, a duration field indicating a value for updating a value of a network allocation vector (NAV), and a wireless communication terminal receiving data. an RA field indicating the address of , a TA field indicating the address of a wireless communication terminal transmitting data, and an FCS field including a cyclical redundancy check (CRC) value for error detection.

In order to inform that transmission to the plurality of second wireless communication terminals is started, the first wireless communication terminal may set the value of the RA field and the value of the TA field in the RTS frame to its own address. For convenience of description, the RTS frame set in this way is referred to as an RTS-to-Self frame. The first wireless communication terminal may transmit the RTS-to-Self frame through a plurality of channels. Specifically, the first wireless communication terminal may transmit the RTS-to-Self frame to a plurality of second wireless communication terminals in the BSS through a plurality of channels. In addition, the first wireless communication terminal may set the value of the duration field based on the transmission time of the RTS-to-Self frame and the data transmission time for the plurality of second wireless communication terminals. Specifically, the first wireless communication terminal sets the value of the duration field as the transmission time of the RTS-to-Self frame, the Short Inter-Frame Space (SIFS) defined in the 802.11 standard, the transmission time of the Poll frame, the SIFS, and the transmission time of the CTS frame. , SIFS, data transmission time, SIFS, and ACK frame transmission time.

At this time, when the wireless communication terminal supporting the embodiment of the present invention receives the RTS-to-Self frame, it receives the signal transmitted by the second wireless communication terminal until the channel allocation information is confirmed. In addition, the wireless communication terminal that does not support the embodiment of the present invention stops and waits for access to the channel due to the duration field value of the RTS-to-Self frame. Therefore, through the RTS-to-Self frame, the first wireless communication terminal can be guaranteed TXOP from both the wireless communication terminal supporting the embodiment of the present invention and the wireless communication terminal not supporting the embodiment of the present invention. A detailed operation in which the first wireless communication terminal transmits data to the plurality of second wireless communication terminals using the RTS-to-Self frame will be described with reference to FIGS. 20 to 29 .

20 shows that an access point simultaneously transmits data to a plurality of stations using an RTS-to-Self frame according to an embodiment of the present invention.

When the channel is idle for a predetermined time, the first wireless communication terminal waits for a random value within a contention window value and then transmits the RTS-to-Self frame to the plurality of channels. Specifically, when the channel is idle for a predetermined time, the first wireless communication terminal waits for a random value within a contention window value and then sends a plurality of RTS-to-Self frames to a plurality of second wireless communication terminals in the BSS. transmit to the channel. In this case, the first wireless communication terminal may transmit the RTS-to-Self frame to a plurality of channels that are idle except for channels currently busy by other users. In this case, the predetermined time may be an Arbitration Inter-Frame Space (AIFS) or a Distributed Inter-Frame Space (DIFS) defined in the 802.11 standard.

The first wireless communication terminal transmits the above-described poll frame to the plurality of second wireless communication terminals. Specifically, the first wireless communication terminal may transmit the above-described poll frame to a plurality of second wireless communication terminals through any one channel. In a specific embodiment, the first wireless communication terminal may transmit the above-described poll frame through a primary channel after a predetermined time. In this case, the first wireless communication terminal may transmit a poll frame after a predetermined time. The constant time may be SIFS.

The plurality of second wireless communication terminals receiving the poll frame acquire channel vector information from the poll frame. Through this, the plurality of second wireless communication terminals may recognize the channel assigned to them. In addition, as described above, the second wireless communication terminal may acquire channel vector information based on the preamble of the communication signal.

The plurality of second wireless communication terminals transmits the CTS frame to the first wireless communication terminal based on the acquired channel vector information. Specifically, the plurality of second wireless communication terminals transmits the CTS frame through channels allocated to each of the plurality of second wireless communication terminals. Specifically, after a predetermined time from the poll frame transmission, the plurality of second wireless communication terminals may transmit the CTS frame to the first wireless communication terminal. In this case, the predetermined time may be SIFS.

The first wireless communication terminal transmits data to a plurality of second wireless communication terminals that have transmitted the CTS frame. Specifically, after a predetermined time from transmission of the CTS frame, the first wireless communication terminal may transmit data to a plurality of second wireless communication terminals that have transmitted the CTS frame. In this case, the predetermined time may be SIFS. Specifically, the first wireless communication terminal may transmit data to the plurality of second wireless communication terminals through a channel allocated to each of the plurality of second wireless communication terminals. The plurality of second wireless communication terminals receiving the data transmits an ACK frame to the first wireless communication terminal. Specifically, after a predetermined time, the plurality of second wireless communication terminals that have received the data may transmit an ACK frame to the first wireless communication terminal. In this case, the predetermined time may be SIFS.

In this way, by using OFDMA, the first wireless communication terminal can transmit data to a plurality of second wireless communication terminals at the same time. However, a frequency channel usable by the first wireless communication terminal is limited. Therefore, the first wireless communication terminal must efficiently allocate available frequency channels to transmit data. In addition, the size of data that the first wireless communication terminal transmits to the plurality of second wireless communication terminals at the same time may be all different. Therefore, it may be inefficient to allocate frequency channels of the same size to all second wireless communication terminals. When the first wireless communication terminal aggregates data to be transmitted to a plurality of second wireless communication terminals and transmits the data to a plurality of second wireless communication terminals simultaneously using all available frequency channels, the first wireless communication terminal receives available frequencies can be used without waste. In addition, in this case, there is no need for the first wireless communication terminal to perform a complicated operation of allocating an available frequency channel to each of the second wireless communication terminals. Accordingly, there is a need for a data transmission method through an aggregated MAC protocol data unit in which a plurality of MAC protocol data units including data to be transmitted to a plurality of second wireless communication terminals are aggregated. In this case, the aggregate MAC protocol data unit for simultaneously transmitting data to the plurality of second wireless communication terminals is different from the existing Aggregate-Mac Protocol Data Unit (A-MPDU) in which MPDUs to be transmitted to the same address are aggregated and transmitted. Accordingly, an aggregate MAC protocol data unit for simultaneously transmitting data to a plurality of second wireless communication terminals is referred to as a multi-terminal A-MPDU or a multi-station A-MPDU.

In addition, the first wireless communication terminal sends a plurality of terminal A-MPDU headers corresponding to each of a plurality of second wireless communication terminals to each of a plurality of second wireless communication terminals through a channel assigned to each of the plurality of second wireless communication terminals. can be transmitted The header signals information about multiple terminal A-MPDUs. In particular, the header may include the address of the second wireless communication terminal corresponding to the header. In addition, the header may include information indicating the location of data corresponding to each of the plurality of second wireless communication terminals. For convenience of description, such information is referred to as start point vector information. The start point vector information may include at least one of a time and a channel through which the second wireless communication terminal can receive data. In addition, the start point vector information may be located after the existing MPDU header. In this case, the wireless communication terminal that does not support the embodiment of the present invention treats the header as a payload. In addition, the wireless communication terminal that does not support the embodiment of the present invention can know that another wireless communication terminal is using the corresponding channel through the header. And the wireless communication terminal that does not support the embodiment of the present invention updates the TXOP based on the value of the duration field included in the header. Through this, compatibility with wireless communication terminals that do not support the embodiment of the present invention can be promoted.

In the embodiment of FIG. 20, when a channel is idle during DIFS, the access point waits for a random value within a contention window and then transmits an RTS-to-Self frame to a plurality of channels. According to a specific embodiment, when a channel is idle during AIFS, the access point may transmit an RTS-to-Self frame to a plurality of channels after waiting for a random value within a contention window. Specifically, the access point includes an idle primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), a fourth sub-channel (Secondary CH#4), and a fifth The RTS-to-Self frame is transmitted to a plurality of stations in the BSS through a secondary channel (Secondary CH#5), a sixth subchannel (Secondary CH#6), and a seventh subchannel (Secondary CH#7).

The access point transmits a poll frame to a plurality of stations. Specifically, the access point transmits a poll frame to a plurality of stations through a primary channel (Primary CH).

A plurality of stations that have received the poll frame acquire channel vector information from the poll frame.

The plurality of stations transmits the CTS frame to the first wireless communication terminal based on the acquired channel vector information. Specifically, the first to seventh stations each have a primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), and a fourth sub-channel (Secondary CH#4). , the CTS frame is transmitted through the fifth sub-channel (Secondary CH#5), the sixth sub-channel (Secondary CH#6), and the seventh sub-channel (Secondary CH#7).

The access point transmits a plurality of terminal A-MPDUs to a plurality of stations that have transmitted the CTS frame. Specifically, the access point provides a primary channel (Primary CH), a first secondary channel (Secondary CH#1), a second secondary channel (Secondary CH#2), and a fourth secondary channel (Secondary CH) to the first to seventh stations, respectively. #4), a plurality of UE A-MPDUs are transmitted through a fifth subchannel (Secondary CH#5), a sixth subchannel (Secondary CH#6), and a seventh subchannel (Secondary CH#7). At this time, the access point transmits the header to the first station through the primary channel (Primary CH), transmits the header to the second station through the first secondary channel (Secondary CH#1), and the second secondary channel (Secondary CH). Transmits the header to the third station through #2), transmits the header to the fourth station through the fourth sub-channel (Secondary CH#4), and transmits the header to the fifth station through the fifth sub-channel (Secondary CH#5) transmits the header to the BTS, transmits the header to the sixth station through the sixth sub-channel (Secondary CH#6), and transmits the header to the seventh station through the seventh sub-channel (Secondary CH#7).

The plurality of stations that have received the plurality of terminal A-MPDUs transmit an ACK frame to the access point. Specifically, the first to seventh stations include a primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), a fourth sub-channel (Secondary CH#4), The ACK frame is transmitted through the fifth sub-channel (Secondary CH#5), the sixth sub-channel (Secondary CH#6), and the seventh sub-channel (Secondary CH#7).

21 shows that an access point simultaneously transmits data to a plurality of stations using an RTS-to-Self frame according to another embodiment of the present invention.

In the above-described embodiment, the first wireless communication terminal provides a plurality of terminals A-MPDU corresponding to each of a plurality of second wireless communication terminals to each of a plurality of second wireless communication terminals through a channel assigned to each of the second wireless communication terminals. headers can be sent. In another specific embodiment, the second wireless communication terminal may transmit headers for a plurality of second wireless communication terminals that receive the plurality of terminal A-MPDUs through any one channel. In this case, any one channel may be a main channel. The header may include the above-described start point vector information. As described above, the start point vector information may include a time and a channel through which the second wireless communication terminal can receive data. In addition, the start point vector information may be located after the existing MPDU header. The header may include all addresses of the plurality of second wireless communication terminals receiving the plurality of terminal A-MPDUs. Therefore, in this embodiment, it is impossible for a wireless communication terminal that does not support the embodiment of the present invention to recognize that a channel used for transmitting a plurality of terminals A-MPDU is used through a header.

In the embodiment of FIG. 21, when the channel is idle during DIFS, the access point waits for a random value within a contention window and then transmits the RTS-to-Self frame to the plurality of channels. According to a specific embodiment, when a channel is idle during AIFS, the access point may transmit an RTS-to-Self frame to a plurality of channels after waiting for a random value within a contention window. Specifically, the access point includes an idle primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), a fourth sub-channel (Secondary CH#4), and a fifth The RTS-to-Self frame is transmitted to a plurality of stations in the BSS through a secondary channel (Secondary CH#5), a sixth subchannel (Secondary CH#6), and a seventh subchannel (Secondary CH#7).

The access point transmits a poll frame to a plurality of stations. Specifically, the access point transmits a poll frame to a plurality of stations through a primary channel (Primary CH).

A plurality of stations that have received the poll frame acquire channel vector information from the poll frame.

The plurality of stations transmit a CTS frame to the access point based on the acquired channel vector information. Specifically, the first to seventh stations each have a primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), and a fourth sub-channel (Secondary CH#4). , transmits the CTS frame to the access point through the fifth sub-channel (Secondary CH#5), the sixth sub-channel (Secondary CH#6), and the seventh sub-channel (Secondary CH#7).

The access point transmits a plurality of terminal A-MPDUs to a plurality of stations that have transmitted the CTS frame. Specifically, the access point provides a primary channel (Primary CH), a first secondary channel (Secondary CH#1), a second secondary channel (Secondary CH#2), and a fourth secondary channel (Secondary CH) to the first to seventh stations, respectively. #4), a plurality of UE A-MPDUs are transmitted through a fifth subchannel (Secondary CH#5), a sixth subchannel (Secondary CH#6), and a seventh subchannel (Secondary CH#7). In this case, the access point transmits headers of a plurality of terminal A-MPDUs corresponding to each of the plurality of stations to the plurality of stations through a channel allocated to each of the plurality of stations.

The plurality of stations that have received the plurality of terminal A-MPDUs transmit an ACK frame to the access point. Specifically, the first to seventh stations include a primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), a fourth sub-channel (Secondary CH#4), The ACK frame is transmitted to the access point through the fifth sub-channel (Secondary CH#5), the sixth sub-channel (Secondary CH#6), and the seventh sub-channel (Secondary CH#7).

22 to 25 , it will be described that a first wireless communication terminal transmits data other than a plurality of terminal A-MPDUs to a plurality of second wireless communication terminals. In this case, the data may be in the form of an A-MPDU.

The first wireless communication terminal may asynchronously transmit data to a plurality of second wireless communication terminals. In detail, data airtimes transmitted from the first wireless communication terminal to each of the plurality of second wireless communication terminals may be different from each other. In addition, the first wireless communication terminal may asynchronously receive data from the plurality of second wireless communication terminals. Specifically, the plurality of second wireless communication terminals each transmit data to the first wireless communication terminal may have different transmission times (data airtime). The amount of data to be transmitted to each of the plurality of second wireless communication terminals may be different. Therefore, when the first wireless communication terminal asynchronously transmits data to a plurality of second wireless communication terminals or asynchronously receives data from a plurality of second wireless communication terminals, the use time of the corresponding channel is reduced to allow other wireless communication terminals to operate. You can maximize the time that the channel can be used. In addition, there is no need for the first wireless communication terminal to perform separate data padding or data fragmentation for synchronization. Also, the first wireless communication terminal does not need to perform scheduling for synchronization. In this embodiment, the first wireless communication terminal may receive an ACK frame from another second wireless communication terminal while transmitting data to any one of the second wireless communication terminals. A case in which the first wireless communication terminal asynchronously transmits data to the plurality of second wireless communication terminals will be described with reference to FIGS. 22 to 23 .

22 shows that the access point allocates one channel to each of a plurality of stations and asynchronously transmits data to the plurality of stations according to an embodiment of the present invention.

In the embodiment of FIG. 22, when a channel is idle during DIFS, the access point waits for a random value within a contention window and then transmits the RTS-to-Self frame to a plurality of channels. According to a specific embodiment, when a channel is idle during AIFS, the access point may transmit an RTS-to-Self frame to a plurality of channels after waiting for a random value within a contention window. Specifically, the access point includes an idle primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), a fourth sub-channel (Secondary CH#4), and a fifth The RTS-to-Self frame is transmitted to a plurality of stations in the BSS through a secondary channel (Secondary CH#5), a sixth subchannel (Secondary CH#6), and a seventh subchannel (Secondary CH#7).

The access point transmits a poll frame to a plurality of stations. Specifically, the access point transmits a poll frame to a plurality of stations through a primary channel (Primary CH). The access point notifies the station to participate in the transmission to the station of the corresponding BSS through transmission of the poll frame.

A plurality of stations that have received the poll frame acquire channel vector information from the poll frame. Through this, a plurality of stations participating in the transmission recognize the channel assigned to them.

The plurality of stations transmit a CTS frame to the access point based on the acquired channel vector information. Specifically, the first to seventh stations each have a primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), and a fourth sub-channel (Secondary CH#4). , transmits the CTS frame to the access point through the fifth sub-channel (Secondary CH#5), the sixth sub-channel (Secondary CH#6), and the seventh sub-channel (Secondary CH#7). A hidden terminal problem can be solved through the transmission of the A-RTS frame of the access point and the transmission of the CTS frame of a plurality of stations.

The access point asynchronously transmits data to a plurality of stations that have transmitted the CTS frame. Specifically, the access point provides a primary channel (Primary CH), a first secondary channel (Secondary CH#1), a second secondary channel (Secondary CH#2), and a fourth secondary channel (Secondary CH) to the first to seventh stations, respectively. #4), the fifth subchannel (Secondary CH#5), the sixth subchannel (Secondary CH#6), and the seventh subchannel (Secondary CH#7) transmit data at different data transmission times.

A plurality of stations receiving data asynchronously transmits an ACK frame to the access point. Specifically, the first to seventh stations include a primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), a fourth sub-channel (Secondary CH#4), The ACK frame is transmitted to the access point through the fifth sub-channel (Secondary CH#5), the sixth sub-channel (Secondary CH#6), and the seventh sub-channel (Secondary CH#7) at the same time.

23 shows that the access point allocates one or more channels to each of a plurality of stations and asynchronously transmits data to the plurality of stations according to an embodiment of the present invention.

In FIG. 23, other operations are the same as in FIG. 22, but for the sixth station, the access point transmits data through the sixth sub-channel (Secondary CH #6) and the seventh sub-channel (Secondary CH #7). In this case, the sixth station may know through the poll frame that it has been allocated the sixth sub-channel (Secondary CH #6) and the seventh sub-channel (Secondary CH #7). For this transmission, the sixth station transmits a CTS frame to each of the sixth sub-channel (Secondary CH #6) and the seventh sub-channel (Secondary CH #7). In addition, after receiving the data, the sixth station transmits an ACK frame to each of the sixth sub-channel (Secondary CH #6) and the seventh sub-channel (Secondary CH #7).

As described above, when a first wireless communication terminal asynchronously transmits data to a plurality of second wireless communication terminals and asynchronously receives data from a plurality of second wireless communication terminals, the first wireless communication terminal While transmitting data to one second wireless communication terminal, it is necessary to receive an ACK frame from another second wireless communication terminal. In addition, in this case, an operation for allocating a channel from the first wireless communication terminal to the second wireless communication terminal may be complicated. In order to solve this problem, the first wireless communication terminal may synchronously transmit data to a plurality of second wireless communication terminals. In detail, the data airtime of the data transmitted from the first wireless communication terminal to each of the plurality of second wireless communication terminals may be the same. In addition, the first wireless communication terminal may receive data synchronously from the plurality of second wireless communication terminals. Specifically, a data airtime of data transmitted from each of the plurality of second wireless communication terminals to the first wireless communication terminal may be the same. For such synchronization, the first wireless communication terminal and the second wireless communication terminal may perform data padding or data fragmentation. Through this, it is possible to simplify the operation in which the first wireless communication terminal allocates a channel to the plurality of second wireless communication terminals.

24 shows that the access point allocates one channel to each of a plurality of stations and synchronously transmits data to the plurality of stations according to an embodiment of the present invention.

In the embodiment of FIG. 24, when the channel is idle during DIFS, the access point waits for a random value within a contention window and then transmits the RTS-to-Self frame to the plurality of channels. Specific embodiment Accordingly, when a channel is idle during AIFS, the access point may transmit an RTS-to-Self frame to a plurality of channels after waiting for a random value within a contention window. Specifically, the access point includes an idle primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), a fourth sub-channel (Secondary CH#4), and a fifth The RTS-to-Self frame is transmitted to a plurality of stations in the BSS through a secondary channel (Secondary CH#5), a sixth subchannel (Secondary CH#6), and a seventh subchannel (Secondary CH#7).

The access point transmits a poll frame to a plurality of stations. Specifically, the access point transmits a poll frame to a plurality of stations through a primary channel (Primary CH). The access point notifies the station to participate in the transmission to the station of the corresponding BSS through transmission of the poll frame.

A plurality of stations that have received the poll frame acquire channel vector information from the poll frame. Through this, a plurality of stations participating in the transmission recognize the channel assigned to them.

The plurality of stations transmit a CTS frame to the access point based on the acquired channel vector information. Specifically, the first to seventh stations each have a primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), and a fourth sub-channel (Secondary CH#4). , transmits the CTS frame to the access point through the fifth sub-channel (Secondary CH#5), the sixth sub-channel (Secondary CH#6), and the seventh sub-channel (Secondary CH#7). A hidden terminal problem can be solved through the transmission of the A-RTS frame of the access point and the transmission of the CTS frame of a plurality of stations.

The access point synchronously transmits data to a plurality of stations that have transmitted the CTS frame. Specifically, the access point provides a primary channel (Primary CH), a first secondary channel (Secondary CH#1), a second secondary channel (Secondary CH#2), and a fourth secondary channel (Secondary CH) to the first to seventh stations, respectively. #4), the fifth subchannel (Secondary CH#5), the sixth subchannel (Secondary CH#6), and the seventh subchannel (Secondary CH#7) transmit data at the same data transmission time.

A plurality of stations receiving data synchronously transmits an ACK frame to the access point. Specifically, the first to seventh stations include a primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), a fourth sub-channel (Secondary CH#4), The ACK frame is transmitted to the access point through the fifth sub-channel (Secondary CH#5), the sixth sub-channel (Secondary CH#6), and the seventh sub-channel (Secondary CH#7) at the same time.

25 shows that the access point allocates one or more channels to each of a plurality of stations and synchronously transmits data to the plurality of stations according to an embodiment of the present invention.

In FIG. 25, other operations are the same as in FIG. 24, but for the sixth station, the access point transmits data through the sixth sub-channel (Secondary CH #6) and the seventh sub-channel (Secondary CH #7). In this case, the sixth station may know through the poll frame that it has been allocated the sixth sub-channel (Secondary CH #6) and the seventh sub-channel (Secondary CH #7). For this transmission, the sixth station transmits a CTS frame to each of the sixth sub-channel (Secondary CH #6) and the seventh sub-channel (Secondary CH #7). In addition, after receiving the data, the sixth station transmits an ACK frame to each of the sixth sub-channel (Secondary CH #6) and the seventh sub-channel (Secondary CH #7).

Through this embodiment, it is possible to simplify the operation of the first wireless communication terminal for allocating a channel to the second wireless communication terminal. In addition, the first wireless communication terminal does not need to perform an operation of simultaneously receiving an ACK frame from another second wireless communication terminal while transmitting data to any one of the second wireless communication terminals.

26 shows that the access point transmits data to a plurality of stations when it does not receive a CTS frame from any one station according to an embodiment of the present invention.

The first wireless communication terminal transmits data to the second wireless communication terminal that has transmitted the CTS frame. If the second wireless communication terminal assigned a channel in the poll frame does not transmit the CTS frame, the first wireless communication terminal does not transmit data to the corresponding terminal. This can be applied to all of the above-described data transmission embodiments using the poll frame.

26 shows that when one station fails to transmit a CTS frame by a hidden node, the access point according to an embodiment of the present invention transmits data to a plurality of stations.

In the embodiment of FIG. 26, when the channel is idle during DIFS, the access point waits for a random value within a contention window and then transmits the RTS-to-Self frame to the plurality of channels. Specific embodiment Accordingly, when a channel is idle during AIFS, the access point may transmit an RTS-to-Self frame to a plurality of channels after waiting for a random value within a contention window. Specifically, the access point includes an idle primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), a third sub-channel (Secondary CH#3), and a fourth To a plurality of stations in the BSS through the sub-channel (Secondary CH#4), the fifth sub-channel (Secondary CH#5), the sixth sub-channel (Secondary CH#6), and the seventh sub-channel (Secondary CH#7) Transmit RTS-to-Self frame.

The access point transmits a poll frame to a plurality of stations. Specifically, the access point transmits a poll frame to a plurality of stations through a primary channel (Primary CH). In this case, the access point allocates a primary channel and a first secondary channel (Secondary CH#1) to a seventh secondary channel (Secondary CH#7) to each of the first to eighth stations, respectively. The access point notifies the station of the corresponding BSS of the channels allocated to the plurality of stations through transmission of the poll frame.

A plurality of stations that have received the poll frame acquire channel vector information from the poll frame. Through this, a plurality of stations participating in the transmission recognize the channel assigned to them.

The plurality of stations receiving the poll frame transmits the CTS frame through channels allocated to each of the plurality of stations. Station 4 to which the assigned channel is not idle does not transmit a CTS frame, and stations 1 to 3 and 5 to 8 have a primary channel and a secondary channel, respectively. The CTS frame is transmitted to the access point through #1) to the second sub-channel (Secondary CH#2) and the fourth sub-channel (Secondary CH#4) to the seventh sub-channel (Secondary CH#7).

The access point transmits data to the station that has transmitted the CTS frame. In this case, the access point may transmit data according to various embodiments described above.

In the above-described embodiment, the first wireless communication terminal was able to simultaneously receive data from a plurality of second wireless communication terminals. However, when the first wireless communication terminal cannot simultaneously receive data from the plurality of second wireless communication terminals, the plurality of second wireless communication terminals simultaneously transmits the CTS frame to the first wireless communication terminal as in the above-described embodiments. Can't send Therefore, in this case, there is a need for another method by which the plurality of second wireless communication terminals can transmit the CTS frame to the first wireless communication terminal.

27 illustrates an operation in which the access point simultaneously transmits data to a plurality of stations when the access point cannot simultaneously receive data from a plurality of stations according to another embodiment of the present invention.

The plurality of second wireless communication terminals may sequentially transmit CTS frames to the first wireless communication terminal. In this case, the plurality of second wireless communication terminals may sequentially transmit CTS frames to the first wireless communication terminal at regular time intervals. Specifically, the second wireless communication terminal may transmit the CTS frame to the first wireless communication terminal after waiting for a time corresponding to an integer multiple of the sum of the transmission times of the SIFS and the CTS frame. In addition, the plurality of second wireless communication terminals may sequentially transmit the CTS frame to the first wireless communication terminal based on the poll frame. In a specific embodiment, the second wireless communication terminal may acquire the CTS frame transmission order assigned to it from the poll frame. Specifically, the arrangement order of the addresses of the second wireless communication terminal included in the poll frame may indicate the CTS frame transmission order of the corresponding second wireless communication terminal. In this case, the channel described as the address of the second wireless communication terminal in the poll frame may indicate a channel allocated to the corresponding second wireless communication terminal as described above.

In another specific embodiment, the number of second wireless communication terminals capable of simultaneously transmitting data to the first wireless communication terminal may be limited. In this case, after a predetermined number of second wireless communication terminals among the plurality of second wireless communication terminals transmit the CTS frame to the first wireless communication terminal, the remaining second wireless communication terminals transmit the CTS frame to the first wireless communication terminal. can In this case, the second wireless communication terminal may obtain an order in which the second wireless communication terminal transmits the CTS frame to the first wireless communication terminal from the poll frame. Specifically, the sort order of the addresses of the second wireless communication terminal included in the CTS frame may indicate the order in which the corresponding second wireless communication terminal transmits the CTS frame.

In the embodiment of FIG. 27, when the channel is idle during DIFS, the access point waits for a random value within a contention window and then transmits the RTS-to-Self frame to the plurality of channels. Specific embodiment Accordingly, when a channel is idle during AIFS, the access point may transmit an RTS-to-Self frame to a plurality of channels after waiting for a random value within a contention window. Specifically, the access point includes an idle primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), a fourth sub-channel (Secondary CH#4), and a fifth The RTS-to-Self frame is transmitted to a plurality of stations in the BSS through a secondary channel (Secondary CH#5), a sixth subchannel (Secondary CH#6), and a seventh subchannel (Secondary CH#7).

The access point transmits a poll frame to a plurality of stations. Specifically, the access point transmits a poll frame to a plurality of stations through a primary channel (Primary CH). The access point notifies the station of the corresponding BSS of the channels allocated to the plurality of stations through transmission of the poll frame.

A plurality of stations that have received the poll frame acquire channel vector information from the poll frame. Through this, a plurality of stations participating in the transmission recognize the channel assigned to them.

A plurality of stations sequentially transmits the CTS frame to the access point through a channel assigned to them. Specifically, after receiving the poll frame and passing the SIFS, the first station transmits the CTS frame to the access point through the primary channel. After the first station transmits the CTS frame and SIFS passes, the second station transmits the CTS frame to the access point through the first secondary channel (Secondary CH#1). After the second station transmits the CTS frame and SIFS passes, the third station transmits the CTS frame to the access point through the second secondary channel (Secondary CH#2). After the third station transmits the CTS frame and SIFS passes, the fifth station transmits the CTS frame to the access point through the fourth secondary channel (Secondary CH#4). After the 5th station transmits the CTS frame and SIFS passes, the 6th station transmits the CTS frame to the access point through the 5th secondary channel (Secondary CH#5). After the 6th station transmits the CTS frame and SIFS passes, the 7th station transmits the CTS frame to the access point through the 6th secondary channel (Secondary CH#6). After the 7th station transmits the CTS frame and SIFS passes, the 8th station transmits the CTS frame to the access point through the 7th secondary channel (Secondary CH#7). In this case, each of the plurality of stations may acquire a CTS frame transmission order assigned to them based on the poll frame as described above. Specifically, the sorting order of addresses of stations included in the poll frame may indicate the CTS frame transmission order of the corresponding station.

The access point transmits data to the station that has transmitted the CTS frame. In this case, the access point may transmit data according to various embodiments described above.

In the above-described embodiment, the second wireless communication terminal transmits the CTS frame to the first wireless communication terminal after a predetermined time from the time when the first wireless communication terminal transmits the poll frame to the second wireless communication terminal. In a specific embodiment, the constant time may be SIFS. When it takes a lot of time for the second wireless communication terminal to process the poll frame, the predetermined time may be longer than the SIFS. Specifically, the constant time may be a PCF inter-frame space (PIFS) defined in 802.11. For example, after the PIFS from when the first wireless communication terminal transmits the poll frame to the plurality of second wireless communication terminals, the plurality of second wireless communication terminals may transmit the CTS frame to the first wireless communication terminal.

28 is a diagram illustrating a case in which an access point transmits data to a plurality of stations after PIFS from when the access point transmits a poll frame to a plurality of stations according to an embodiment of the present invention, and the plurality of stations sends a CTS frame to the access point shows the transmission of

In the embodiment of FIG. 28, when the channel is idle during DIFS, the access point waits for a random value within a contention window and then transmits the RTS-to-Self frame to the plurality of channels. Specific embodiment Accordingly, when a channel is idle during AIFS, the access point may transmit an RTS-to-Self frame to a plurality of channels after waiting for a random value within a contention window. Specifically, the access point includes an idle primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), a fourth sub-channel (Secondary CH#4), and a fifth The RTS-to-Self frame is transmitted to a plurality of stations in the BSS through a secondary channel (Secondary CH#5), a sixth subchannel (Secondary CH#6), and a seventh subchannel (Secondary CH#7).

The access point transmits a poll frame to a plurality of stations. Specifically, the access point transmits a poll frame to a plurality of stations through a primary channel (Primary CH). The access point notifies the station of the corresponding BSS of the channels allocated to the plurality of stations through transmission of the poll frame.

A plurality of stations that have received the poll frame acquire channel vector information from the poll frame. Through this, a plurality of stations participating in the transmission recognize the channel assigned to them.

After the PIFS from when the access point transmits the poll frame, the plurality of stations transmits the CTS frame through the channels allocated to them. A fourth station whose assigned channel is not in an idle state does not transmit a CTS frame. The first to third stations and the fifth to eighth stations respectively have a primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), and a fourth sub-channel, respectively. The CTS frame is transmitted to the access point through (Secondary CH#4) to the seventh sub-channel (Secondary CH#7).

The access point transmits data to the station that has transmitted the CTS frame. In this case, the access point may transmit data according to various embodiments described above.

In the above-described embodiment, the first wireless communication terminal transmits the poll frame after transmitting the RTS-to-Self frame to the second wireless communication terminal. According to a specific embodiment, the first wireless communication terminal may transmit a poll frame and transmit an RTS-to-Self frame. In this case, the second wireless communication terminal can know that data will be transmitted to itself before receiving the RTS-to-Self frame. In addition, at this time, the second wireless communication terminal can know the channel assigned to it. Accordingly, the second wireless communication terminal has sufficient time to prepare for transmission of the CTS frame to the first wireless communication terminal.

29 shows that an access point transmits a poll frame to a plurality of stations, transmits an RTS-to-Self frame, and then transmits data according to an embodiment of the present invention.

In the embodiment of FIG. 29, when the channel is idle during DIFS, the access point waits for a random value within a contention window and then transmits a poll frame to a plurality of stations. According to a specific embodiment, when a channel is idle during AIFS, the AP may transmit a poll frame to a plurality of stations after waiting for a random value within a contention window. Specifically, the access point transmits a poll frame to a plurality of stations through a primary channel (Primary CH). The access point notifies the station of the corresponding BSS of the channels allocated to the plurality of stations through transmission of the poll frame. In addition, the plurality of stations that have received the poll frame acquire channel vector information from the poll frame. Through this, a plurality of stations participating in the transmission recognize the channel assigned to them. Through this, the plurality of stations can know which data is to be transmitted and the channel assigned to them before receiving the RTS-to-Self frame. Through this, the plurality of stations may prepare for transmission of the CTS frame in advance.

The access point transmits the RTS-to-Self frame through a plurality of channels. Specifically, the access point includes an idle primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), a fourth sub-channel (Secondary CH#4), and a fifth The RTS-to-Self frame is transmitted to a plurality of stations in the BSS through a secondary channel (Secondary CH#5), a sixth subchannel (Secondary CH#6), and a seventh subchannel (Secondary CH#7).

A plurality of stations transmit a CTS frame through a channel assigned to them. A fourth station whose assigned channel is not in an idle state does not transmit a CTS frame. The first to third stations and the fifth to eighth stations respectively have a primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), and a fourth sub-channel, respectively. The CTS frame is transmitted to the access point through (Secondary CH#4) to the seventh sub-channel (Secondary CH#7).

The access point transmits data to the station that has transmitted the CTS frame. In this case, the access point may transmit data according to various embodiments described above.

In another specific embodiment, the first wireless communication terminal may transmit data to a plurality of wireless communication terminals by modifying the RTS frame without using a poll frame. For convenience of description, the modified RTS frame is referred to as an M-RTS frame. This will be described with reference to FIG. 30 .

30 shows that an access point transmits data to a plurality of stations using M-RTS according to an embodiment of the present invention.

The first wireless communication terminal may transmit each of the plurality of M-RTS frames to each of the plurality of second wireless communication terminals. In this case, the M-RTS frame may be an existing RTS frame in which the address of the second wireless communication terminal to which the channel through which the M-RTS frame is transmitted is set as an RA field value. Accordingly, the RA field values of the plurality of M-RTS frames are different from each other. In this embodiment, the second wireless communication terminal should be scanning all channels.

In another specific embodiment, the first wireless communication terminal may transmit an M-RTS frame to a plurality of second wireless communication terminals through any one channel. In this case, any one channel may be a main channel. In addition, the M-RTS frame may have a structure in which the existing RTS frame further includes the aforementioned channel vector information. For example, the structure of the M-RTS frame may be a structure in which channel vector information is located after the FCS field of the existing RTS frame.

In the embodiment of FIG. 30, when a channel is idle during DIFS, the access point waits for a random value within a contention window, and then transmits an M-RTS frame to a plurality of stations through a plurality of channels. According to a specific embodiment, when a channel is idle during AIFS, the access point may transmit an M-RTS frame to a plurality of stations through a plurality of channels after waiting for a random value within a contention window. Specifically, the access point includes an idle primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), a fourth sub-channel (Secondary CH#4), and a fifth An M-RTS frame is transmitted to a plurality of stations through a secondary channel (Secondary CH#5), a sixth subchannel (Secondary CH#6), and a seventh subchannel (Secondary CH#7).

A plurality of stations recognize a channel to which the M-RTS is transmitted and a channel allocated to them based on the RA field value of the M-RTS.

A plurality of stations transmit a CTS frame through a channel assigned to them. A fourth station whose assigned channel is not in an idle state does not transmit a CTS frame. The first to third stations and the fifth to eighth stations respectively have a primary channel (Primary CH), a first sub-channel (Secondary CH#1), a second sub-channel (Secondary CH#2), and a fourth sub-channel, respectively. The CTS frame is transmitted to the access point through (Secondary CH#4) to the seventh sub-channel (Secondary CH#7).

The access point transmits data to the station that has transmitted the CTS frame. In this case, the access point may transmit data according to various embodiments described above.

As described above, the plurality of second wireless communication terminals may simultaneously transmit data to the first wireless communication terminal. To this end, a method in which a first wireless communication terminal allocates a channel to a plurality of wireless communication terminals and a method in which a plurality of second wireless communication terminals secure TXOP are required. This will be described with reference to FIGS. 31 to 41 . In particular, through FIGS. 31 to 37, after the first wireless communication terminal transmits data to the plurality of second wireless communication terminals, it is described that the plurality of second wireless communication terminals transmit data to the first wireless communication terminal . For convenience of description, the transmission of data from the first wireless communication terminal to the second wireless communication terminal is referred to as downlink transmission, and the transmission of data by the second wireless communication terminal to the first wireless communication terminal is referred to as uplink transmission. .

The second wireless communication terminal may notify the first wireless communication terminal of whether there is data to be transmitted by transmitting a specific frame. Accordingly, the frame transmitted from the second wireless communication terminal to the first wireless communication terminal may indicate whether there is data to be transmitted from the second wireless communication terminal to the first wireless communication terminal. In a specific embodiment, the ACK frame transmitted from the second wireless communication terminal to the first wireless communication terminal may indicate whether there is data to be transmitted from the second wireless communication terminal to the first wireless communication terminal. In addition, a more data field of a frame that the second wireless communication terminal transmits to the first wireless communication terminal may indicate whether the second wireless communication terminal has data to transmit to the first wireless communication terminal. For example, the more data field of the ACK frame transmitted from the second wireless communication terminal to the first wireless communication terminal may indicate whether the second wireless communication terminal has data to transmit to the first wireless communication terminal. The more data field indicates that there is a bufferable unit (BU) to be transmitted from the access point to the station in a power saving (PS) mode. Accordingly, the station receiving the frame in which the more data field is 1 keeps waking up in the power saving mode and waits for data transmission from the access point. However, if it is not a downlink transmission session in which the access point transmits data to the station, the more data field is not used. Therefore, as described above, the second wireless communication terminal may use the more data field for the purpose of notifying whether the second wireless communication terminal has data to transmit to the first wireless communication terminal. Through this embodiment, the first wireless communication terminal can know that there is data to be transmitted to the second wireless communication terminal. Specifically, that there is data to be transmitted may mean a buffer state indicating whether there is data to be transmitted to the first wireless communication terminal in the buffer of the second wireless communication terminal.

The first wireless communication terminal allocates a channel to be used by the second wireless communication terminal. The first wireless communication terminal transmits the above-described poll frame to the plurality of second wireless communication terminals. In this case, the poll frame may include channel vector information including information on a channel allocated to the second wireless communication terminal. In addition, the first wireless communication terminal may transmit the poll frame through the main channel. In another specific embodiment, the first wireless communication terminal may transmit a poll frame to a plurality of second wireless communication terminals through the channel previously used to transmit data. In another specific embodiment, the first wireless communication terminal may transmit a poll frame to a plurality of wireless communication terminals through a channel allocated to each of the second wireless communication terminals. Also, the poll frame may be referred to as a trigger frame as described above.

The second wireless communication terminal acquires channel vector information based on the poll frame. Specifically, the second wireless communication terminal may acquire information about the channel allocated to the second wireless communication terminal by the first wireless communication terminal from the channel vector information of the poll frame.

The second wireless communication terminal transmits data to the first wireless communication terminal through a channel assigned to it. According to a specific embodiment, after receiving the poll frame, the second wireless communication terminal may transmit data to the first wireless communication terminal without transmitting a separate frame. Specifically, when all TXOPs of a channel used for an uplink session are protected in a downlink transmission session, the second wireless communication terminal may transmit data to the first wireless communication terminal after receiving the poll frame. In this case, since the second wireless communication terminal receives the poll frame and transmits data after a predetermined time, the data transmission time is the same as that of the other second wireless communication terminal. In another specific embodiment, the second wireless communication terminal may transmit an ACK frame for the poll frame to end the downlink transmission session, and transmit data to the first wireless communication terminal. Specifically, after the second wireless communication terminal transmits the ACK frame, the first wireless communication terminal transmits the CTS-to-Self frame to secure the TXOP of the uplink transmission session. In this case, the CTS-to-Self frame indicates a case in which the RA field of the CTS frame is the MAC address of the wireless communication terminal transmitting the CTS frame. The wireless communication terminal receiving the CTS-to-Self frame does not access the corresponding channel. Therefore, the CTS-to-Self frame serves to secure TXOP. After the first wireless communication terminal secures the TXOP of the uplink transmission session, the second wireless communication terminal may transmit data to the first wireless communication terminal.

31 shows that a plurality of stations transmit data to an access point after receiving data from the access point according to an embodiment of the present invention.

31 , the access point transmits data to a plurality of stations. Specifically, the access point transmits data to the first station, the third station, and the fourth station. To this end, the access point transmits an RTS frame to a plurality of stations and receives a CTS frame from the plurality of stations to secure TXOP.

The first station, the third station, and the fourth station receiving data from the access point transmit an ACK frame to the access point. In this case, the first station and the third station having data to transmit to the access point transmit an ACK frame indicating whether there is data to be transmitted. In this case, when the value of the more data field of the ACK frame is 1, the ACK frame may indicate that the station transmitting the corresponding ACK frame has data to transmit to the access point.

The access point allocates channels to the first station and the third station. The access point transmits a poll frame including information on the assigned channel to the first station and the third station.

The first station and the third station receive the poll frame and transmit an ACK frame for the poll frame to the access point. As described above, after receiving the poll frame, the first station and the third station may transmit data to the access point without transmitting a separate frame.

The access point transmits a CTS-to-Self frame to a plurality of stations. Through this, the access point secures a TXOP through which the first station and the third station can transmit data to themselves.

Each of the first station and the third station transmits data to the access point through a channel assigned to it.

The first wireless communication terminal may allocate a channel to be used for the uplink transmission session to the plurality of second wireless communication terminals based on the channel used in the downlink transmission session and the plurality of second wireless communication terminals participating in the downlink transmission. This will be described with reference to FIG. 32 .

32 shows that each of a plurality of stations transmits data to the access point through a channel used when the access point transmits data to each of the plurality of stations according to an embodiment of the present invention.

The first wireless communication terminal may allocate a channel used for downlink transmission as a channel for uplink transmission to the second wireless communication terminal participating in downlink transmission. In this case, each of the first wireless communication terminal and the second wireless communication terminal may perform downlink transmission using the TXOP secured during downlink transmission. Specifically, the TXOP set and updated through the duration field values of the first wireless communication terminal and the second wireless communication terminal RTS frame and the CTS frame may be used. This channel allocation may be specifically performed through the following operation.

The second wireless communication terminal transmits to the first wireless communication terminal at least one of information indicating whether there is data to be transmitted to the first wireless communication terminal, the size of data to be transmitted to the first wireless communication terminal, and information about available channels. can Specifically, the second wireless communication terminal generates a frame including at least one of information indicating whether there is data to be transmitted to the first wireless communication terminal, the size of data to be transmitted to the first wireless communication terminal, and information about available channels. 1 It can be transmitted to a wireless communication terminal. For example, the ACK frame transmitted from the second wireless communication terminal to the first wireless communication terminal includes information indicating whether there is data to be transmitted to the first wireless communication terminal, the size of data to be transmitted to the first wireless communication terminal, and an available channel. It may include at least one of information. In this case, the available channel information informs the first wireless communication terminal of a hidden terminal that the first wireless communication terminal cannot detect. Through this, the first wireless communication terminal allocates the remaining channels except for the channel used by the hidden terminal to prevent transmission collision with the hidden terminal when the second wireless communication terminal transmits data to the first wireless communication terminal. In addition, the first wireless communication terminal may prepare a buffer for data reception based on the size of the data to be transmitted.

The first wireless communication terminal allocates a channel to each of a plurality of second wireless communication terminals based on the information received from the second wireless communication terminal, a channel used in downlink transmission, and a plurality of second wireless communication terminals participating in downlink transmission. can In detail, the first wireless communication terminal may allocate a channel allocated to the plurality of second wireless communication terminals in downlink transmission to the plurality of wireless communication terminals as the uplink transmission channel. Through this, the first wireless communication terminal and the second wireless communication terminal can utilize the TXOP secured during the downlink transmission session.

The first wireless communication terminal transmits a poll frame to a plurality of stations. As described above, the poll frame includes information about a channel allocated by the first wireless communication terminal to the second wireless communication terminal. The first wireless communication terminal may transmit a poll frame to a plurality of stations after a predetermined time from when the ACK frame is received. Specifically, the first wireless communication terminal may transmit a poll frame to a plurality of stations after SIFS from when the ACK frame is received. According to the complexity of the scheduling or operation time, the first wireless communication terminal may transmit the poll frame to the plurality of stations after the SIFS or longer time from when the ACK frame is received.

In the embodiment of FIG. 32 , the access point transmits data to a plurality of stations. Specifically, the access point includes a primary channel (Primary CH), a first sub-channel (Secondary CH#1) to a second sub-channel (Secondary CH#2), and a fourth sub-channel (Secondary CH#4) to a seventh sub-channel. Data is transmitted to each of the first to third stations and the fifth to seventh stations through (Secondary CH#7), respectively. To this end, the access point transmits an RTS frame to a plurality of stations and receives a CTS frame from the plurality of stations to secure TXOP.

The plurality of stations that have received data from the access point transmit an ACK frame to the access point through a channel assigned to each of the plurality of stations. Specifically, the first to third stations and the fifth to seventh stations include a primary channel (Primary CH), a first secondary channel (Secondary CH#1) to a second secondary channel (Secondary CH#2), and a fourth The ACK frame is transmitted to the access point through each of the sub-channels (Secondary CH#4) to the seventh sub-channel (Secondary CH#7). In this case, each of the first to third stations and the sixth to seventh stations having data to transmit to the access point transmits an ACK frame indicating whether there is data to be transmitted. In this case, when the value of the more data field of the ACK frame is 1, the ACK frame may indicate that the station transmitting the corresponding ACK frame has data to transmit to the access point.

The access point allocates a channel to be used for data transmission to a plurality of stations that have transmitted an ACK frame indicating that there is data to be transmitted to the access point. Specifically, the access point allocates a channel to be used for data transmission to each of the first to third stations and the sixth to seventh stations. Specifically, the access point may allocate the channels used by the first to third stations and the sixth to seventh stations, respectively, to the first to third stations and the sixth station, respectively, in the downlink transmission session.

The access point transmits a poll frame including information on the assigned channel to the plurality of stations. The access point transmits a poll frame including information on the assigned channel to the first to third stations and the sixth to seventh stations.

After receiving the poll frame, the plurality of stations transmit data to the access point. Specifically, the first to third stations and the sixth to seventh stations transmit data to the access point after receiving the poll frame.

Each of the plurality of stations transmits data to the access point through a channel assigned to it. The first to third stations and the sixth to seventh stations each have a primary channel (Primary CH), a first secondary channel (Secondary CH#1) to a second secondary channel (Secondary CH#2), and a fifth part Data is transmitted to the access point through each of the channels (Secondary CH#4) to the seventh sub-channel (Secondary CH#7).

The access point receiving the data includes a primary channel (Primary CH), first sub-channels (Secondary CH#1) to second sub-channels (Secondary CH#2), and fifth sub-channels (Secondary CH#4) to seventh channels. The ACK frame is transmitted to the first to third stations and the sixth to seventh stations through each of the secondary channels (Secondary CH#7).

However, there may be a case in which only some of the plurality of second wireless communication terminals that have received data from the first wireless communication terminal transmit data to the first wireless communication terminal. Alternatively, there may be a case where a difference between the size of data received from the first wireless communication terminal and the size of data to be transmitted by the second wireless communication terminal is large. In this case, as described with reference to FIG. 32 , it may be inefficient in terms of bandwidth utilization to use the channel used by the second wireless communication terminal for downlink transmission as it is. Accordingly, the first wireless communication terminal may allocate a channel to the second wireless communication terminal without considering the channel allocated to the second wireless communication terminal during downlink transmission. This will be described with reference to FIGS. 33 and 34 .

33 shows that a plurality of stations transmit data to an access point by receiving a channel allocation regardless of whether the access point uses a corresponding channel when transmitting data to the plurality of stations according to an embodiment of the present invention.

The first wireless communication terminal may allocate a channel for uplink transmission to each of the plurality of second wireless communication terminals regardless of whether a corresponding channel is used for downlink transmission to the plurality of second wireless communication terminals. In this case, the channel is allocated according to the current channel condition, so that the channel usage rate can be increased. Accordingly, it is possible to improve the data transmission speed from the second wireless communication terminal to the first wireless communication terminal.

As described above, the second wireless communication terminal transmits at least one of information indicating whether there is data to be transmitted to the first wireless communication terminal, the size of data to be transmitted to the first wireless communication terminal, and information on available channels to the first wireless communication terminal. It can be transmitted to the communication terminal. Specifically, the second wireless communication terminal generates a frame including at least one of information indicating whether there is data to be transmitted to the first wireless communication terminal, the size of data to be transmitted to the first wireless communication terminal, and information about available channels. 1 can be transmitted to a wireless communication terminal. For example, the ACK frame transmitted from the second wireless communication terminal to the first wireless communication terminal includes information indicating whether there is data to be transmitted to the first wireless communication terminal, the size of data to be transmitted to the first wireless communication terminal, and an available channel. It may include at least one of information. In this case, the available channel information informs the first wireless communication terminal of a hidden terminal that the first wireless communication terminal cannot detect. Through this, the first wireless communication terminal allocates the remaining channels except for the channel used by the hidden terminal to prevent transmission collision with the hidden terminal when the second wireless communication terminal transmits data to the first wireless communication terminal. In addition, the first wireless communication terminal may prepare a buffer for data reception based on the size of the data to be transmitted.

The first wireless communication terminal may allocate a channel to each of the plurality of second wireless communication terminals based on the information received from the second wireless communication terminal. Specifically, the first wireless communication terminal is based on at least one of information indicating whether there is data to be transmitted from the second wireless communication terminal, the size of data to be transmitted by the second wireless communication terminal, and information about available channels. A communication terminal may allocate a channel to be used for uplink transmission. For example, the first wireless communication terminal may allocate the bandwidth of the channel according to the size of data to be transmitted by each of the plurality of second wireless communication terminals. Through this, the first wireless communication terminal can maximize channel use efficiency.

However, unlike the embodiment of FIG. 32, since the TXOP secured during uplink transmission is not utilized, there is a risk of collision with transmission of another wireless communication terminal when the second wireless communication terminal transmits data to the first wireless communication terminal. . Specifically, when the first wireless communication terminal transmits the RTS frame through all channels in the idle state before downlink transmission, the wireless communication terminal around the first wireless communication terminal sets the NAV value by the RTS frame. Therefore, the possibility of collision with the data transmission of the wireless communication terminal around the first wireless communication terminal is small. However, since the second wireless communication terminal has not previously transmitted the CTS frame through the assigned channel, the NAV may not be set. However, even in this case, since the wireless communication terminal around the second wireless communication terminal performs CCA (Clear Channel Assessment) by energy detection (ED), the possibility of data transmission collision may not be high.

33 , the access point transmits data to a plurality of stations. Specifically, the access point includes a primary channel (Primary CH), a first sub-channel (Secondary CH#1) to a second sub-channel (Secondary CH#2), and a fourth sub-channel (Secondary CH#4) to a seventh sub-channel. Data is transmitted to each of the first to third stations and the fifth to seventh stations through (Secondary CH#7), respectively. To this end, the access point transmits an RTS frame to a plurality of stations and receives a CTS frame from the plurality of stations to secure TXOP.

The plurality of stations that have received data from the access point transmit an ACK frame to the access point through a channel assigned to each of the plurality of stations. Specifically, the first to third stations and the fifth to seventh stations include a primary channel (Primary CH), a first secondary channel (Secondary CH#1) to a second secondary channel (Secondary CH#2), and a fourth The ACK frame is transmitted to the access point through each of the sub-channels (Secondary CH#4) to the seventh sub-channel (Secondary CH#7). In this case, each of the first to third stations and the sixth to seventh stations having data to transmit to the access point transmits an ACK frame indicating that there is data to be transmitted. In this case, when the value of the more data field of the ACK frame is 1, the ACK frame may indicate that the station transmitting the corresponding ACK frame has data to transmit to the access point.

The access point allocates a channel to be used for data transmission to a plurality of stations that have transmitted an ACK frame indicating that there is data to be transmitted to the access point. Specifically, the access point allocates a channel to be used for data transmission to each of the first to third stations and the sixth to seventh stations. Specifically, the access point may allocate a channel to be used for uplink transmission to each of the first, third, and sixth stations regardless of whether the corresponding channel is used in the downlink session. Specifically, the access point allocates a primary channel (Primary CH) to a first station, a first secondary channel (Secondary CH#1) to a second station, and a second secondary channel (Secondary CH#2) to a third station. ), allocating a fourth sub-channel (Secondary CH#4) and a fifth sub-channel (Secondary CH#5) to the sixth station, and the sixth sub-channel (Secondary CH#6) and the second sub-channel (Secondary CH#5) to the seventh station. Allocate 7 secondary channels (Secondary CH#5). In this case, the access point allocates the fourth subchannel (Secondary CH#4) not used by the sixth station to the sixth station.

The access point transmits a poll frame including information on the assigned channel to the plurality of stations. The access point transmits a poll frame including information on the assigned channel to the first to third stations and the sixth to seventh stations.

After receiving the poll frame, the plurality of stations transmit data to the access point. Specifically, the first to third stations and the sixth to seventh stations transmit data to the access point after receiving the poll frame.

Each of the plurality of stations transmits data to the access point through a channel assigned to it. The first to third stations and the sixth to seventh stations each have a primary channel (Primary CH), a first secondary channel (Secondary CH#1) to a second secondary channel (Secondary CH#2), and a fifth part Data is transmitted to the access point through each of the channels (Secondary CH#4) to the seventh sub-channel (Secondary CH#7).

The access point receiving the data includes a primary channel (Primary CH), first sub-channels (Secondary CH#1) to second sub-channels (Secondary CH#2), and fifth sub-channels (Secondary CH#4) to seventh channels. The ACK frame is transmitted to the first to third stations and the sixth to seventh stations through each of the secondary channels (Secondary CH#7).

31 and 32 are described above, the second wireless communication terminal may transmit information about an available channel to the first wireless communication terminal, and through this, data transmission collides with transmission of another wireless communication terminal It has been demonstrated that this can be prevented. The first wireless communication terminal may allocate a channel to be used by the second wireless communication terminal for uplink transmission based on the available channel information transmitted by the second wireless communication terminal and the available channel information detected by the first wireless communication terminal. This will be described with reference to FIG. 34 .

34 is a diagram illustrating an access point allocating a channel to a plurality of stations based on information about an available channel transmitted by the station, and transmitting data to the access point according to the channel assigned to the plurality of stations according to an embodiment of the present invention show what to do

The second wireless communication terminal may detect an available channel and transmit information about the available channel to the first wireless communication terminal. In detail, the frame transmitted from the second wireless communication terminal to the first wireless communication terminal may include information about an available channel detected by the second wireless communication terminal. In this case, the frame transmitted from the second wireless communication terminal to the first wireless communication terminal may be an ACK frame.

The first wireless communication terminal determines the channel to be used by the second wireless communication terminal for uplink transmission to the second wireless communication terminal based on the available channel information received from the second wireless communication terminal and the available channel information detected by the first wireless communication terminal. can be assigned In this case, the first wireless communication terminal may detect an available channel with CCA through energy sensing. In addition, as described above, the first wireless communication terminal further receives at least one of information indicating that there is data to be transmitted by the second wireless communication terminal and the size of data to be transmitted by the second wireless communication terminal, and receives it in the second wireless communication A channel to be used by the second wireless communication terminal for uplink transmission may be allocated to the second wireless communication terminal in consideration of the available channel information received from the terminal and the available channel information detected by the first wireless communication terminal.

34, the access point receives information from the third station that the third secondary channel (Secondary CH#3) is available. In addition, the access point detects that the third secondary channel (Secondary CH#3) is available. Accordingly, the access point allocates the third sub-channel (Secondary CH#3) as well as the second sub-channel (Secondary CH#2) to the third station, and the third station allocates the second sub-channel (Secondary CH#2) and the second sub-channel (Secondary CH#2) to the third station. Data is transmitted to the access point through the third channel (Secondary CH#3). Except for this, operations of the access point and the plurality of stations are the same as in the embodiment of FIG. 33 .

In this embodiment, the first wireless communication terminal does not consider whether it is a previously used channel, but only considers whether the second wireless communication terminal determines the currently available channel and whether it is the first available channel, so that the channel usage rate can be increased. . However, there is a higher possibility that data transmission of the second wireless communication terminal collides with data transmission of another wireless communication terminal than in the case of allocating a channel with TXOP secured using the RTS frame and the CTS frame.

As described above, the second wireless communication terminal may receive the poll frame from the first wireless communication terminal and transmit an ACK frame for the poll frame to end the downlink transmission session. In this case, the second wireless communication terminal may transmit data to the first wireless communication terminal through a contention procedure. This will be described with reference to FIG. 35 .

35 shows that an access point secures a TXOP through a contention procedure and a CTS-to-Self frame, and a plurality of stations transmit data to the access point according to an embodiment of the present invention.

The second wireless communication terminal receives the poll frame from the first wireless communication terminal, transmits an ACK frame for the poll frame, and ends the downlink transmission session. Thereafter, the first wireless communication terminal transmits CTS-to-Self through a contention procedure. Specifically, the first wireless communication terminal transmits a CTS-to-Self frame to a plurality of second wireless communication terminals through a channel allocated to the plurality of second wireless communication terminals using a contention procedure. In a specific embodiment, when the channel allocated to the second wireless communication terminal is idle for a predetermined time, the first wireless communication terminal may wait for a random value within the contention window. In this case, the predetermined time may be AIFS or DIFS. If the corresponding channel is idle even after waiting for a random value, the first wireless communication terminal may transmit data to the second wireless communication terminal through the channel allocated to the second wireless communication terminal. In this case, the second wireless communication terminal determines whether the CTS-to-Self frame is transmitted through a channel assigned to it within a predetermined time. For convenience of description, in this case, a predetermined time is referred to as a UL Timer. When the CTS-to-Self frame is transmitted within the UL Timer, the second wireless communication terminal transmits data to the access point through a channel allocated thereto. If the CTS-to-Self frame is not transmitted within the UL Timer, the second wireless communication terminal transmits data to the access point through a channel allocated to it using a contention procedure. Specifically, when the channel allocated to the second wireless communication terminal is idle for a predetermined time, the second wireless communication terminal may wait for a random value within the contention window. In this case, the predetermined time may be AIFS or DIFS. If the corresponding channel is idle even after waiting for a random value, the second wireless communication terminal may transmit data to the first wireless communication terminal through a channel assigned to it.

In this embodiment, since the first wireless communication terminal performs the contention procedure based on the UL timer, the UL timer, the contention window, and the TXOP value must be appropriately set so that a plurality of second wireless communication terminals can efficiently provide the first wireless communication terminal with the UL timer. data can be transmitted. In order to increase the priority of data transmission of the second wireless communication terminal, the value of the UL timer must be large, the value of the contention window must be small, and the value of the TXOP must be large. Conversely, in order to lower the priority of data transmission of the second wireless communication terminal, the value of the UL timer must be small, the value of the contention window must be large, and the value of the TXOP must be small. Values of the UL timer, contention window (CW), and TXOP may be defined by the following equation.

In this case, alpha and beta of the equations are variables whose value increases when the priority of data transmission of the second wireless communication terminal increases, and gamma of the equation is a variable whose value decreases when the priority of data transmission of the second wireless communication terminal increases. . In addition, TXOP _base is a reference value for TXOP operation, UL_Timer _base is a reference value for operation of UL timer value, and CW _base is a reference value for operation of CW value. Specifically, at this time, the values of the UL timer, CW, and TXOP may be changed according to a specific BSS situation.

In addition, as described above, when the channel allocated to the second wireless communication terminal is in an idle state, the first wireless communication terminal calculates a random value within the contention window value, and even after waiting for the calculated random value, the corresponding channel remains idle. decide whether If the corresponding channel is idle even after waiting for the calculated random value, the first wireless communication terminal transmits CTS-to-Self through the corresponding channel. In this case, in order to give priority to data transmission of a plurality of second wireless communication terminals, the first wireless communication terminal may obtain a random value a plurality of times and wait for a minimum value among them. Specifically, the first wireless communication terminal may obtain a random value as many as the number of second wireless communication terminals to transmit data to the first wireless communication terminal and wait for the minimum value among them. According to this method, a probability distribution is shown according to the probability distribution function below.

Therefore, if the number of users n increases, the probability that the first wireless communication terminal has a low back-off value increases.

35, the plurality of stations receiving the poll frame transmits an ACK frame to the access point.

Thereafter, the access point determines whether the channels allocated to the plurality of stations are idle during the DIFS time. According to a specific embodiment, the access point may determine whether the channels allocated to the plurality of stations are idle during the AIFS time. When the channel allocated to the plurality of stations is in the idle state, the access point obtains a random value within the contention window, waits, and then determines whether the corresponding channel is in the idle state. In this case, the access point may obtain a random value as much as the number of stations that will transmit data to the access point as described above and wait for the minimum value among them. When the corresponding channel is in the idle state, the access point transmits the CTS-to-Self frame to the plurality of stations through the channel allocated to the plurality of stations. Specifically, in the embodiment of FIG. 35, the access point transmits a CTS-to-Self frame to the first station through a primary channel (Primary CH). In addition, the access point transmits the CTS-to-Self frame to the second station through the first secondary channel (Secondary CH#1). In addition, the access point transmits the CTS-to-Self frame to the third station through the second sub-channel (Secondary CH#2) and the third sub-channel (Secondary CH#3). In addition, the access point transmits the CTS-to-Self frame to the sixth station through the fourth sub-channel (Secondary CH#4) and the fifth sub-channel (Secondary CH#5). In addition, the access point transmits the CTS-to-Self frame to the seventh station through the sixth sub-channel (Secondary CH#6) and the seventh sub-channel (Secondary CH#7).

A plurality of stations that have received the CTS-to-Self frame transmit data to the access point through the assigned channel. Specifically, the first station transmits data to the access point through a primary channel (Primary CH). In addition, the second station transmits data to the access point through the first secondary channel (Secondary CH#1). In addition, the third station transmits the data frame to the access point through the second sub-channel (Secondary CH#2) and the third sub-channel (Secondary CH#3). In addition, the sixth station transmits the data frame to the access point through the fourth sub-channel (Secondary CH#4) and the fifth sub-channel (Secondary CH#5). In addition, the seventh station transmits the data frame to the access point through the sixth sub-channel (Secondary CH#6) and the seventh sub-channel (Secondary CH#7).

As described above, the frame transmitted from the second wireless communication terminal to the first wireless communication terminal may indicate that the second wireless communication terminal has data to transmit to the first wireless communication terminal. In a specific embodiment, the ACK frame transmitted from the second wireless communication terminal to the first wireless communication terminal may indicate that there is data to be transmitted from the second wireless communication terminal to the first wireless communication terminal. Specifically, by setting a specific field of the ACK frame to a specific value, the second wireless communication terminal may indicate that there is data to be transmitted to the first wireless communication terminal.

Also, the second wireless communication terminal may set a value of a duration field of a frame indicating that there is data to be transmitted based on a time required for data transmission. Accordingly, the NAV of the neighboring wireless communication terminal receiving the frame indicating that there is data to be transmitted may be reset. Through this, when the second wireless communication terminal transmits data through the assigned channel, it is possible to prevent another wireless communication terminal from accessing the corresponding channel.

In this case, when there is no data to be transmitted from the second wireless communication terminal to the first wireless communication terminal, the second wireless communication terminal may transmit a conventional ACK frame in which a specific field is not set to a specific value. Through this, the second wireless communication terminal having no data to transmit to the first wireless communication terminal can quickly return the assigned channel. A specific embodiment will be described with reference to FIGS. 36 to 37 .

36 is a diagram illustrating data transmission between an access point and a plurality of stations when some stations among a plurality of stations have no data to transmit to the access point according to an embodiment of the present invention.

In the embodiment of FIG. 36 , the first station, the second station, the sixth station, and the seventh station have data to transmit to the access point. Accordingly, the first station, the second station, the sixth station, and the seventh station notify the access point that there is data to be transmitted through the ACK frame for the data transmission of the access point. However, since there is no data to be transmitted to the access point, the third station and the fifth station return the corresponding channel by transmitting the conventional ACK frame. Other operations of the access point and the plurality of stations are the same as in the above-described embodiments.

37 shows data transmission between the access point and the plurality of stations when there is no data to be transmitted from the plurality of stations to the access point according to an embodiment of the present invention.

37 , the first station, the second station, the third station, the fifth station, the sixth station, and the seventh station receive data from the access point. Since the first station, the second station, the third station, the fifth station, the sixth station, and the seventh station have no data to transmit to the access point, they transmit the conventional ACK frame and return the assigned channel.

As such, when there is no data to be transmitted from the second wireless communication terminal to the first wireless communication terminal, the embodiment of the present invention operates in the same manner as that of the existing wireless communication terminal. Therefore, the transmission method between a plurality of wireless communication terminals according to an embodiment of the present invention does not cause degradation of the performance of the wireless communication terminal in the existing environment.

In the above-described embodiment, when the first wireless communication terminal transmits a frame indicating whether there is data to be transmitted from the second wireless communication terminal, the first wireless communication terminal immediately transmits a frame including information on a channel allocated to the second wireless communication terminal. In this case, the first wireless communication terminal should receive a frame indicating whether there is data to be transmitted from the second wireless communication terminal, immediately allocate a channel to the second wireless communication terminal, and perform transmission scheduling. Accordingly, in the case of this embodiment, the first wireless communication terminal may not have enough time to efficiently allocate the channel and to adjust the transmission schedule and the other second wireless communication terminal. Therefore, an embodiment for solving this is required. This will be described with reference to FIG. 38 . In addition, as described above, a frame including information on a channel allocated to the second wireless communication terminal may be referred to as a trigger frame or a poll frame.

38 shows that an access point transmits a trigger frame to a plurality of stations according to another embodiment of the present invention.

When the channel is idle for a predetermined time, the first wireless communication terminal transmits a trigger frame through a contention procedure in the corresponding channel. In this case, the channel may be a main channel. In another specific embodiment, it may be a channel allocated to the second wireless communication terminal for data transmission of the second wireless communication terminal. Specifically, when the channel is idle for a predetermined time, the first wireless communication terminal calculates a random value within the contention window. Thereafter, the first wireless communication terminal waits by the calculated random value. If the corresponding channel is idle even after waiting for the calculated random value, the first wireless communication terminal transmits a trigger frame through the corresponding channel. In this case, the trigger frame may indicate that a specific channel is allocated to the second wireless communication terminal as well as indicate that the second wireless communication terminal can randomly access a channel in a specific range.

The second wireless communication terminal receives the trigger frame.

The second wireless communication terminal acquires information about a channel allocated to it based on the trigger frame. In this case, the information on the allocated channel may be the channel vector information described above. Also, the information on the allocated channel may be information indicating that a channel in a specific range can be randomly accessed.

The second wireless communication terminal transmits data to the first wireless communication terminal through a channel assigned to it. As such, the second wireless communication terminal does not transmit the ACK frame for the trigger frame, but directly transmits data. At this time, when the first wireless communication terminal receives data from any one of the second wireless communication terminals among the plurality of second wireless communication terminals to which the channel is allocated through the trigger frame, it is determined that the transmission of the trigger frame is successful. Therefore, when data is received from any one of the second wireless communication terminals among the second wireless communication terminals, the first wireless communication terminal does not perform a procedure according to transmission failure, such as increasing the size of the contention window. When the information on the assigned channel indicated by the trigger frame indicates only random access, the first wireless communication terminal determines that the transmission is successful even if the first wireless communication terminal does not receive the data. Therefore, the first wireless communication terminal does not perform the procedure according to the transmission failure even when the first wireless communication terminal does not receive data.

As described above, the second wireless communication terminal may transmit a frame indicating whether there is data to be transmitted to the first wireless communication terminal to the first wireless communication terminal. This will be described in detail with reference to FIGS. 39 to 41 .

39 shows the structure of a frame indicating that a station has data to transmit to an access point according to another embodiment of the present invention.

The second wireless communication terminal may indicate whether there is data to be transmitted to the first wireless communication terminal through a specific field value of a frame transmitted to the first wireless communication terminal. Specifically, the second wireless communication terminal may indicate whether there is data to be transmitted to the first wireless communication terminal through the value of the more data field of the frame transmitted to the first wireless communication terminal. For example, when there is data to be transmitted to the first wireless communication terminal, the second wireless communication terminal may set the value of the more data field of the frame to be transmitted to the first wireless communication terminal to 1. The more data field is a field included in the frame control field of the MAC frame. Specifically, the more data field indicates that a bufferable unit (BU) to be transmitted from the access point to the station in a power saving (PS) mode exists. Accordingly, the station receiving the frame in which the more data field is 1 keeps waking up in the power saving mode and waits for data transmission from the access point. However, when the access point is not for downlink data transmission in which data is transmitted to the station, the more data field is not used. Therefore, as described above, the second wireless communication terminal may use the more data field for the purpose of notifying whether the second wireless communication terminal has data to transmit to the first wireless communication terminal.

In this case, the frame transmitted by the second wireless communication terminal may be an uplink transmission data frame transmitted from the second wireless communication terminal to the first wireless communication terminal. In addition, the frame transmitted by the second wireless communication terminal may be at least one of an ACK frame and a block ACK frame for data transmitted by the first wireless communication terminal.

Upon receiving the frame, the first wireless communication terminal may perform scheduling for a plurality of second wireless communication terminals and allocate channels to the plurality of second wireless communication terminals. Specifically, when the value of the field indicating whether there is data to be transmitted to the first wireless communication terminal of the frame received by the first wireless communication terminal indicates that there is data to be transmitted to the first wireless communication terminal, the first wireless communication terminal is the corresponding The second wireless communication terminal that has transmitted the frame is added to the scheduling list for channel allocation. In addition, when the value of the field indicating whether there is data to be transmitted to the first wireless communication terminal of the frame received by the first wireless communication terminal indicates that there is no data to be transmitted to the first wireless communication terminal, the first wireless communication terminal is The second wireless communication terminal that has transmitted the frame is deleted from the scheduling list for channel allocation.

In addition, the first wireless communication terminal transmits a trigger frame including information on the allocated channel to the second wireless communication terminal.

If the second wireless communication terminal does not receive the trigger frame for a predetermined time from when the second wireless communication terminal transmits the frame indicating that there is data to be transmitted to the first wireless communication terminal, the second wireless communication terminal is transmit data. In this case, the second wireless communication terminal may set a field value indicating whether there is data to be transmitted to the first wireless communication terminal of the frame for transmitting data to no data to be transmitted. For example, the second wireless communication terminal may set the value of the more data field of the frame for transmitting data to 0. The predetermined time for which the second wireless communication terminal waits may be a timer value according to an access category (AC). The first wireless communication terminal that has received the frame indicating that there is no data to transmit does not include channel allocation information for the first wireless communication terminal that has transmitted the frame in the trigger frame.

40 shows that a plurality of stations notifies an access point of whether there is data to be transmitted through an ACK frame according to another embodiment of the present invention.

In the embodiment of FIG. 40 , the access point transmits data to the first to seventh stations.

The first to seventh stations receive data from the access point.

The first station, the second station, the third station, the fifth station, the sixth station, and the seventh station transmit an ACK frame indicating that there is data to be transmitted to the access point. Specifically, the first station, the second station, the third station, the fifth station, the sixth station, and the seventh station transmit an ACK frame in which the value of the more data field is 1 to the access point. The fourth station transmits an ACK frame indicating that there is no data to transmit to the access point. Specifically, the fourth station transmits an ACK frame in which the value of the more data field is 0 to the access point.

The access point transmits the trigger frame to the first station, the second station, the third station, the fifth station, the sixth station, and the seventh station.

The first station, the second station, the third station, the fifth station, the sixth station, and the seventh station acquire information about the channel allocated to them based on the trigger frame.

The first station, the second station, the third station, the fifth station, the sixth station, and the seventh station transmit data to the access point through a channel assigned to them.

41 shows that a plurality of stations notifies an access point of whether there is data to be transmitted through an uplink transmission data frame according to another embodiment of the present invention.

The first to seventh stations transmit data to the access point. In this case, the first station, the second station, the third station, the fifth station, the sixth station, and the seventh station transmit a data frame indicating that there is data to be transmitted to the access point to the access point. Specifically, the first station, the second station, the third station, the fifth station, the sixth station, and the seventh station transmit a data frame in which the value of the more data field is 1.

The access point transmits an ACK frame to the first to seventh stations.

Other operations of the access point and the plurality of stations are the same as in the embodiment of FIG. 40 described above.

In this way, the second wireless communication terminal may transmit a frame indicating whether there is data to be transmitted to the first wireless communication terminal in its own buffer state. Based on the buffer state of the second wireless communication terminal, the first wireless communication terminal can efficiently allocate channels and schedules to the plurality of second wireless communication terminals. Through this, the plurality of second wireless communication terminals can efficiently transmit data to the first wireless communication terminal.

The operations of the first wireless communication terminal and the second wireless communication terminal according to the above-described embodiments will be described with reference to FIGS. 42 to 43 .

42 is a ladder diagram illustrating an operation in which a first wireless communication terminal transmits data to a second wireless communication terminal according to an embodiment of the present invention.

The first wireless communication terminal 400 transmits a trigger frame to the second wireless communication terminal 500 . The trigger frame includes information on channels allocated to a plurality of second wireless communication terminals 500 for communication with the first wireless communication terminal 400 . In this case, the trigger frame may be referred to as a poll frame as described above. In addition, the first wireless communication terminal 400 may transmit a trigger frame to the plurality of second wireless communication terminals 500 to the plurality of second wireless communication terminals 500 through the main channel. In another specific embodiment, the first wireless communication terminal 400 transmits a trigger frame to the plurality of second wireless communication terminals 500 through a channel to which the plurality of second wireless communication terminals 200 are allocated, respectively. 2 may be transmitted to the wireless communication terminal 500 .

The information on the allocated channel included in the trigger frame may include information on the channel and information on the sub-channel. In this case, the channel information is information about a channel having a bandwidth equal to or greater than the minimum unit frequency bandwidth. In addition, the sub-channel information is information about a sub-channel having a bandwidth less than or equal to the minimum unit frequency bandwidth as a sub-band included in the channel. Specifically, the channel information may be an index indicating a channel. Also, the sub-channel information may be an index indicating a sub-channel.

Also, in a specific embodiment, the first wireless communication terminal 400 may transmit an RTS-to-Self frame that is an RTS frame having the address of the first wireless communication terminal as a reception address through a plurality of channels. Through this, the first wireless communication terminal can secure the TXOP of the channel through which the RTS-to-Self frame is transmitted. In a specific embodiment, the first wireless communication terminal 400 may transmit the trigger frame after transmitting the RTS-to-Self frame. In another specific embodiment, the first wireless communication terminal 400 may transmit the RTS-to-Self frame after transmitting the trigger frame.

In another specific embodiment, the first wireless communication terminal 400 may transmit an RTS frame including channel information allocated to the second wireless communication terminal 500 instead of the trigger frame.

The second wireless communication terminal 500 may transmit a CTS frame in response to the RTS-to-Self frame to the first wireless communication terminal 400 through a channel allocated to it. In a specific embodiment, when the number of wireless communication terminals capable of accessing the first wireless communication terminal at one time is limited, the plurality of second wireless communication terminals 500 may sequentially transmit CTS frames. In this case, the plurality of second wireless communication terminals 500 may acquire the transmission order of the CTS frame based on the trigger frame.

The second wireless communication terminal 500 acquires information about an allocated channel based on the frame received from the first wireless communication terminal 400 (S303).

The first wireless communication terminal 400 transmits data to the second wireless communication terminal 500 through the channel allocated to the second wireless communication terminal 500 (S305). In this case, the first wireless communication terminal 500 may synchronize a data transmission time (data airtime) with a data transmission time (data airtime) for another second wireless communication terminal. Specifically, the first wireless communication terminal 500 may use at least one of padding and fragmentation to synchronize data transmission time (data airtime) with data transmission time (data airtime) for another second wireless communication terminal. there is. In another specific embodiment, the first wireless communication terminal 500 does not synchronize the data transmission time with respect to another second wireless communication terminal, and sets the transmission time according to the amount of data to be transmitted to the second wireless communication terminal can decide In a specific embodiment, the first wireless communication terminal 400 may transmit data to the plurality of second wireless communication terminals 500 through a plurality of terminal A-MPDUs.

43 is a ladder diagram illustrating an operation in which a second wireless communication terminal transmits data to a first wireless communication terminal according to an embodiment of the present invention.

The second wireless communication terminal 500 transmits a frame indicating whether there is data to be transmitted to the first wireless communication terminal 400 to the first wireless communication terminal 400 (S501). In this case, a specific field of the frame indicating whether there is data to be transmitted to the first wireless communication terminal 400 may indicate whether there is data to be transmitted. In a specific embodiment, the more data field of the frame indicating whether there is data to be transmitted to the first wireless communication terminal 400 may indicate whether there is data to be transmitted. For example, when the value of the more data field of the frame indicating whether there is data to be transmitted to the first wireless communication terminal 400 is 1, it may indicate that there is data to be transmitted to the first wireless communication terminal 400 . In addition, the frame indicating whether there is data to be transmitted to the first wireless communication terminal 400 includes an ACK frame, a block ACK frame, and uplink data transmitted by the second wireless communication terminal 500 to the first wireless communication terminal 400 . It may be at least one of the frames.

In addition, the frame indicating whether there is data to be transmitted may include at least one of a size of data to be transmitted to the first wireless communication terminal 400 and information about an available channel detected by the second wireless communication terminal 500 . there is.

The first wireless communication terminal 400 transmits a trigger frame to the second wireless communication terminal 500 (S503). The trigger frame includes information about channels allocated to the plurality of second wireless communication terminals 500 for communication with the first wireless communication terminal 400 . In this case, the trigger frame may be the same as described with reference to FIG. 42 . Specifically, the first wireless communication terminal 400 may transmit a trigger frame based on a frame indicating whether there is data to be transmitted by the second wireless communication terminal 500 . In a specific embodiment, the first wireless communication terminal 400 may allocate a channel to the second wireless communication terminal 500 based on a frame indicating whether there is data to be transmitted by the second wireless communication terminal 500 . there is. Also, the first wireless communication terminal 400 may perform scheduling based on a frame indicating whether there is data to be transmitted from the second wireless communication terminal 500 . The first wireless communication terminal 400 may generate a trigger frame based on such channel allocation and scheduling. In addition, when the channel allocated to the second wireless communication terminal 500 is idle for more than a predetermined time, the first wireless communication terminal 400 may transmit a trigger frame to the second wireless communication terminal 500 through the corresponding channel. there is. In this case, the predetermined time may be AIFS or DIFS. In a specific embodiment, the first wireless communication terminal 400 may receive the ACK frame for the trigger frame from the second wireless communication terminal 500 and transmit the CTS frame to the second wireless communication terminal 500 .

The second wireless communication terminal 500 acquires information about an allocated channel based on the frame received from the first wireless communication terminal 400 (S505).

The second wireless communication terminal 500 transmits data to the first wireless communication terminal 500 through a channel assigned to it (S507). In a specific embodiment, after the first wireless communication terminal 400 transmits the CTS-to-Self frame, the second wireless communication terminal 500 transmits data to the first wireless communication terminal 500 through a channel allocated thereto. can be transmitted.

As described above, the present invention has been described using wireless LAN communication as an example, but the present invention is not limited thereto and may be equally applied to other communication systems such as cellular communication. Further, although the methods, apparatuses, and systems of the present invention have been described with reference to specific embodiments, some or all of the components, operations, and/or operations of the present invention may be implemented using a computer system having a general-purpose hardware architecture.

Features, structures, effects, etc. described in the above embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, features, structures, effects, etc. illustrated in each embodiment can be combined or modified for other embodiments by those of ordinary skill in the art to which the embodiments belong. Accordingly, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention.

Although the embodiment has been described above, it is only an example and does not limit the present invention, and those of ordinary skill in the art to which the present invention pertains are not exemplified above in a range that does not depart from the essential characteristics of the present embodiment. It will be appreciated that various modifications and applications are possible. For example, each component specifically shown in the embodiment can be implemented by modification. And differences related to such modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

Claims (6)

In the base wireless communication terminal,
transceiver; and
including a processor;
the processor
Transmitting a first non-data frame to a first plurality of wireless communication terminals using the transceiver, wherein the first non-data frame is a frame for securing TXOP (Transmit Opportunity) and a predetermined use of a frequency band Indicate the first channel through the index indicating the pattern,
receiving at least one second non-data frame from at least one of the first plurality of wireless communication terminals through the first channel using the transceiver
base radio communication terminal. In claim 1,
the processor
Simultaneously transmitting a plurality of first data frames to a plurality of second wireless communication terminals using the transceiver and synchronizing the transmission time (air time) of the first plurality of data frames
base radio communication terminal. In claim 2,
and inserting padding into at least one of the first plurality of data frames to synchronize transmission times (air times) of the first plurality of data frames.
base radio communication terminal. In a wireless communication terminal,
transceiver; and
including a processor;
the processor
Receive a first non-data frame simultaneously with at least one first plurality of wireless communication terminals using the transceiver, wherein the first non-data frame is a frame for securing TXOP (Transmit Opportunity) and a frequency band Indicate the first channel through an index indicating a predetermined usage pattern for
When the first non-data frame indicates an association identifier (ID) of the wireless communication terminal, at least one second non-data frame is provided to the base wireless communication terminal through the first channel using the transceiver. sending data frames

wireless communication terminal. In claim 4,
The processor receives a first data frame from the base wireless communication terminal simultaneously with receiving a second data frame of a second wireless communication terminal using the transceiver,
The transmission time (air time) of the first data frame is synchronized with the transmission time (air time) of the second data frame.
wireless communication terminal. In claim 5,
Padding is used to synchronize the transmission time (air time) of the first data frame and the transmission time (air time) of the second data frame.
wireless communication terminal.

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