KR20170038746A - Method, apparatus and system for controlling interference of overlapping bss - Google Patents

Abstract

The present invention relates to a method, an apparatus and a system for controlling an interference in a basic service set (BSS) overlapping environment, and more specifically, to an operational mode of a wireless LAN communication apparatus for controlling an interference generated in a BSS overlapped environment. According to an embodiment of the present invention, the apparatus includes a transceiver for transmitting and receiving a wireless signal, and a processor for controlling operations of the transceiver. The processor is configured to receive communication environment information indicating a communication environment from at least one wireless communication terminal through the transceiver, determine a distance between the wireless communication terminal and another wireless communication terminal based on the received communication environment information, classify the at least one wireless communication terminal into at least one group based on the determined distance, and provide an access point for transmitting a wireless signal through the transceiver based on the group.

Description

[0001] METHOD, APPARATUS AND SYSTEM FOR CONTROLLING INTERFERENCE OF OVERLAPPING BSS FOR INTERFERENCE CONTROL IN BSS ENVIRONMENT [

The present invention relates to a method, apparatus and system for interference control in a BSS (Basic Service Set) superposition environment, and more particularly to a method, apparatus and system for controlling interference in a BSS .

Recently, as the spread of mobile devices has expanded, wireless LAN technology capable of providing fast wireless Internet service has attracted much attention. Wireless LAN technology is a technology that allows wireless devices such as smart phones, smart pads, laptop computers, portable multimedia players, and embedded devices to wirelessly access the Internet based on wireless communication technology in close range.

Since the initial wireless LAN technology supports a speed of 1 to 2 Mbps through frequency hopping, spread spectrum, and infrared communication using a 2.4 GHz frequency through Institute of Electrical and Electronics Engineers (IEEE) 802.11, (Orthogonal Frequency Division Multiplex) can be applied to support a maximum speed of 54Mbps. In IEEE 802.11, IEEE 802.11 has also improved the quality of service (QoS), the access point (AP) protocol compatibility, security enhancement, radio resource measurement, wireless access vehicular interworking with external networks, wireless network management, and the like are being put into practical use or under development.

In IEEE 802.11, IEEE 802.11b supports communication speeds of up to 11 Mbps using frequencies in the 2.4 GHz band. IEEE 802.11a, which has been commercialized since IEEE 802.11b, uses the frequency of the 5GHz band instead of the 2.4GHz band, thereby reducing the interference effect compared to the frequency of the highly congested 2.4GHz band. Using OFDM technology, To 54Mbps. However, IEEE 802.11a has a short communication distance compared to IEEE 802.11b. IEEE 802.11g, like IEEE 802.11b, uses a frequency of 2.4GHz band to achieve a communication speed of up to 54Mbps and has received considerable attention because it meets backward compatibility. It is in the lead.

IEEE 802.11n is a technical standard established to overcome the limitation of communication speed which is pointed out as a vulnerability in wireless LAN. IEEE 802.11n aims to increase the speed and reliability of the network and to extend the operating distance of the wireless network. More specifically, IEEE 802.11n supports high throughput (HT) with data rates 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 Multiple Inputs and Multiple Outputs (MIMO) technology. In addition, this specification uses a coding scheme for transmitting multiple duplicate copies in order to increase data reliability, and may also use Orthogonal Frequency Division Multiplex (OFDM) to increase the speed.

Recently, the need for a new wireless LAN system to support a very high throughput (VHT) that is higher than the data processing speed supported by the IEEE 802.11n has been increasing, Is emerging. IEEE 802.11ac supports wide bandwidth (80MHz ~ 160MHz) at 5GHz frequency. Although the IEEE 802.11ac standard is defined only in the 5GHz band, early 11ac chipsets will also support operation in the 2.4GHz band for backward compatibility with existing 2.4GHz band products. At this time, 802.11ac supports bandwidth up to 40MHz at 2.4GHz. Theoretically, according to this specification, the wireless LAN speed of multiple terminals can be at least 1 Gbps and the maximum single link speed can be at least 500 Mbps. This is accomplished by extending the concept of wireless interfaces accepted in 802.11n, including wider radio frequency bandwidth (up to 160 MHz), more MIMO spatial streams (up to 8), multiuser MIMO, and high density modulation (up to 256 QAM). In addition, IEEE 802.11ad is a method of transmitting data using a 60 GHz band instead of the existing 2.5 GHz / 5 GHz. IEEE 802.11ad is a transmission standard that provides a maximum speed of 7Gbps using beamforming technology, and is suitable for streaming high bit rate video such as large amount of data and uncompressed HD video. However, the 60GHz frequency band has a disadvantage in that it is difficult to pass through obstacles, and therefore, it can be used only between devices in a near space.

On the other hand, as the number of installed base stations for wireless LAN access, that is, the number of access points installed, various problems are occurring. Currently, about 1/2 of Internet traffic depends on Wi-Fi. This causes interference among wireless LAN devices connected to adjacent different access points, that is, wireless LAN devices belonging to different BSSs. For example, in the current IEEE 802.11ac technical standard, a broader frequency band of 20 MHz / 40 MHz / 80 MHz / 160 MHz can be used, so that a channel partially overlapping or fully overlapping between adjacent access points The possibility of use is increasing. Therefore, the above-mentioned problem of overlapping BSS (OBSS) interference has emerged as an important issue in terms of efficient use of frequency resources.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a wireless LAN device capable of minimizing interference between wireless communication terminals in an environment in which BSSs are overlapped and capable of increasing spatial reuse in a multi- System and a method of wireless LAN communication.

In addition, the present invention has an object of providing a wireless LAN communication method capable of enhancing communication efficiency of an entire wireless LAN system by sharing information related to wireless communication of each wireless communication apparatus.

According to an aspect of the present invention, there is provided a wireless communication system including: a transceiver for transmitting and receiving a radio signal; And a processor for controlling operations of the transceiver, wherein the processor is configured to receive communication environment information indicating a communication environment from at least one wireless communication terminal through the transceiving unit, A wireless communication terminal, comprising: a wireless communication terminal; a wireless communication terminal; a wireless communication terminal; a wireless communication terminal; a wireless communication terminal; The access point may be provided with a plurality of access points.

Here, the processor transmits a radio signal to a plurality of radio communication terminals included in one of the same group through a multi-user multiple input / multiple output through the transceiver.

Here, the communication environment information may include a BSS (Basic Service Set) distinguisher or a device distinguisher included in a wireless signal received by the wireless communication terminal, and intensity information of the wireless signal, Information for distinguishing a BSS to which a wireless communication apparatus that has transmitted a signal belongs, and the device distinguisher is information for distinguishing a wireless communication apparatus that has transmitted the wireless signal.

Here, the BSS distinguisher includes BSS color information of the access point, the device distinguisher includes an association ID (AID) of the wireless communication terminal, and the strength information of the wireless signal includes Received Signal Strength Index (RSSI).

Here, the distance is determined based on the degree of similarity of the intensity information of the BSS distinguisher, the device distinguisher, or the radio signal sensed by each of the radio communication terminals.

Here, the processor transmits a trigger signal for requesting transmission of the communication environment information to the wireless communication terminal through the transmission / reception unit, receives the communication environment information corresponding to the trigger signal from the wireless communication terminal do.

Wherein the processor selects at least one of the BSS distinguisher or the device distinguisher and the trigger signal indicates that the wireless communication terminal that senses the wireless signal including the selected BSS distinguisher or the selected device distinguisher has the communication environment information As shown in FIG.

Here, the communication environment information is information selected by the wireless communication terminal based on the time at which the wireless signal was received or the intensity information of the wireless signal.

Here, the processor refers to the communication environment information to identify an external access point of another BSS that overlaps with the BSS of the access point, and the processor uses the transmission / reception unit to wirelessly communicate with the access point and the external access point, Receiving, from the external access point, resource unit information, which is information on a resource unit used for transmitting a radio signal through a relay wireless communication terminal for transmitting and receiving a signal, And a radio communication terminal in a signal interference group which is a group including a radio communication terminal that causes signal interference with the radio communication terminals in the other BSS among the groups, Lt; RTI ID = 0.0 > It utilizes a resource unit.

Here, the processor uses the transceiver to receive preamble configuration information of a radio signal, radio signal transmission timing information of the access point, and radio signal transmission timing information of the external access point from the external access point through the relay wireless communication terminal do.

Here, the processor generates the same preamble as the external access point by referring to the preamble configuration information, and when transmitting a radio signal through the transceiver, synchronizes with the radio signal transmission of the external access point to transmit the same preamble do.

Here, the processor separates the preamble and the data field of the radio signal when the radio signal is transmitted through the transceiver, and discontinuously transmits the data field in the time domain after completion of the preamble transmission.

Here, the radio signal transmission timing information includes preamble transmission timing information and data field transmission timing information of the access point and the external access point, and when the processor transmits a radio signal through the transceiver, Transmits the separated preamble at the preamble transmission timing different from the preamble transmission timing of the external access point and transmits the separated data field at the same data field transmission timing as the data field transmission timing of the external access point.

According to another embodiment of the present invention, there is provided a wireless communication terminal comprising: a transceiver for transmitting and receiving a radio signal; And a processor for controlling operation of the transceiver, wherein the processor is configured to receive a radio signal transmitted from an external radio communication apparatus through the transceiver, extract communication environment information indicating a communication environment from the radio signal, The base station transmits the communication environment information to an access point included in a basic service set (BSS) same as the wireless communication terminal through the transceiving unit, and when receiving a radio signal from the access point through the transceiving unit, Based on the communication environment information, the access point determines the distance between the respective wireless communication terminals in the BSS based on the communication environment information, Characterized in that the wireless communication terminal classifies the wireless communication terminal Can be provided.

Here, when receiving a signal from a wireless communication device of another BSS that overlaps with the BSS when receiving a wireless signal from the access point, the processor may transmit the wireless signal to the access point and an external Transmitting a signal requesting sharing of wireless communication related information to an access point, transmitting resource unit information, which is information on a resource unit received from the external access point in response to a signal requesting sharing of the information, And receives a data field of a radio signal transmitted from the access point using a resource unit of a frequency band different from a frequency band used by the external access point.

According to another embodiment of the present invention, there is provided a control method of an access point, comprising: receiving communication environment information indicating a communication environment from at least one wireless communication terminal; Determining a distance between each wireless communication terminal and another wireless communication terminal based on the received communication environment information; Classifying the wireless communication terminals into at least one group based on the determined distances; And performing transmission of the wireless signal based on the group.

Identifying an external access point of another BSS that overlaps with the BSS of the access point by referring to the communication environment information; And resource unit information, which is information on a resource unit used for transmission of a radio signal with the external access point through a relay wireless communication terminal that transmits and receives a radio signal with the access point and the external access point, Receiving; And selecting a resource unit in a band different from a frequency band used by the external access point with reference to the resource unit information, wherein the step of performing transmission of the radio signal comprises: The radio base station uses the selected resource unit when transmitting a data field of a radio signal to a radio communication terminal of a signal interference group which is a group including a radio communication terminal causing signal interference with a radio communication terminal in the BSS.

According to another embodiment of the present invention, there is provided a method of controlling a wireless communication terminal, comprising: receiving a wireless signal transmitted from an external wireless communication apparatus; Extracting communication environment information indicating a communication environment from the wireless signal; Transmitting the communication environment information to an access point included in the same BSS (Basic Service Set) as the wireless communication terminal; And receiving, upon receiving a wireless signal from the access point, a wireless signal transmitted by the access point based on the group, the group comprising: The distance between each wireless communication terminal is discriminated, and the wireless communication terminals in the BSS are classified based on the discriminated distance.

Receiving a signal from a wireless communication terminal of another BSS overlapped with the BSS when receiving a wireless signal from the access point; Transmitting a signal requesting sharing of wireless communication related information to the access point and an external access point included in the other BSS; And transmitting resource unit information to the access point, the resource unit information being information about a resource unit received from the external access point, wherein the step of receiving the wireless signal comprises: And receives the data field of the radio signal transmitted using the resource unit of the frequency band different from the frequency band used by the point.

According to the embodiment of the present invention, it is possible to reduce radio signal interference that may occur in multi-user communication in the OBSS, thereby greatly improving the performance of the entire WLAN system. In particular, it is possible to maximize the space recycling due to the redundant application of the MU-MIMO scheme and the OFDMA scheme.

Also, according to the embodiment of the present invention, information between different BSSs can be shared through a relay wireless communication terminal, and scheduling for reducing collision and interference of a wireless signal of the OBSS is possible based on the shared information.

The present invention can be applied to various communication devices such as a station or an access point using a wireless LAN, a station using a cellular communication, or a base station.

1 is a diagram illustrating a wireless LAN system according to an embodiment of the present invention.
2 is a diagram illustrating an independent BSS that is a wireless LAN system according to another embodiment of the present invention.
3 is a block diagram showing a configuration of a wireless communication terminal according to an embodiment of the present invention.
4 is a block diagram showing a configuration of an access point according to an embodiment of the present invention.
5 is a diagram illustrating a process in which a wireless communication terminal establishes a link with an access point.
6 is a diagram illustrating a passive scanning method of a wireless communication terminal according to an embodiment of the present invention.
7 is a diagram illustrating a method of active scanning of a wireless communication terminal according to an embodiment of the present invention.
8 is a diagram illustrating a multiple BSS environment according to an embodiment of the present invention.
9 is a diagram illustrating a method by which a wireless communication terminal transmits communication environment information to an access point according to an embodiment of the present invention.
10 is a diagram illustrating a method in which a wireless communication terminal transmits communication environment information to an access point according to another embodiment of the present invention.
11 is a diagram illustrating a multiple BSS environment according to another embodiment of the present invention.
12 is a diagram illustrating an embodiment of the present invention in which an OFDMA scheme is applied to a multiple BSS environment.
FIG. 13 shows a transmission method of a radio signal according to an embodiment of the present invention.
FIG. 14 shows a transmission method of a radio signal according to another embodiment of the present invention.
15 is a diagram illustrating a radio signal transmission method according to another embodiment of the present invention.
16 is a diagram illustrating information sharing according to an embodiment of the present invention.
17 is a diagram illustrating a control method of a wireless communication terminal and a control method of an access point according to an embodiment of the present invention.

As used herein, terms used in the present invention are selected from general terms that are widely used in the present invention while taking into account the functions of the present invention. However, these terms may vary depending on the intention of a person skilled in the art, custom or the emergence of new technology. Also, in certain cases, there may be a term arbitrarily selected by the applicant, and in this case, the meaning thereof will be described in the description of the corresponding invention. Therefore, it is intended that the terminology used herein should be interpreted relative to the actual meaning of the term, rather than the nomenclature, and its content throughout the specification.

Throughout the specification, when a configuration is referred to as being "connected" to another configuration, it is not limited to the case where it is "directly connected," but also includes "electrically connected" do. Also, when an element is referred to as " including " a specific element, it is meant to include other elements, rather than excluding other elements, unless the context clearly dictates otherwise. In addition, the limitations of " above " or " below ", respectively, based on a specific threshold value may be appropriately replaced with " An access point may be referred to as an " AP " for ease of description throughout the specification, a " wireless communication terminal " may be referred to as a " user device, , &Quot; station " or " STA ". Further, throughout the specification, the term "wireless communication device" may be a term generally referred to in the broad sense of "access point" and "wireless communication terminal".

The present application claims priority based on Korean Patent Application Nos. 10-2015-0138268 and 10-2016-0004463, and the embodiments and descriptions described in the above applications, which form the basis of the priority, Are to be included in the detailed description of the present invention.

The present invention relates to a method, an apparatus and a system for interference control in a BSS overlapping environment, and more particularly, to a method of operating a wireless LAN communication apparatus for controlling interference generated in a BSS overlapping environment. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

1 illustrates a wireless LAN system according to an embodiment of the present invention. A WLAN system includes one or more Basic Service Sets (BSSs), which represent a collection of devices that can successfully communicate and communicate with one another. In general, a BSS can be divided into an infrastructure BSS (infrastructure BSS) and an independent BSS (IBSS). FIG. 1 shows the infrastructure BSS.

1, an infrastructure BSS (BSS1, BSS2) includes one or more stations STA1, STA2, STA3, STA4, STA5, an access point (PCP / AP) 1, PCP / AP-2), and a distribution system (DS) for connecting a plurality of access points (PCP / AP-1, PCP / AP-2).

A station (STA) is an arbitrary device including a medium access control (MAC) conforming to the IEEE 802.11 standard and a physical layer interface for a wireless medium, and is broadly referred to as a non-access point non-AP) station as well as an access point (AP). In this specification, the term 'terminal' may refer to a non-AP STA or an AP, or may be used to refer to both. The station for wireless communication includes a processor and a transmit / receive unit, and may further include a user interface unit, a display unit, and the like according to an embodiment. The processor may perform various processes for generating frames to be transmitted over the wireless network, processing frames received through the wireless network, and controlling other stations. The transmitting and receiving unit is functionally connected to the processor and transmits and receives a frame through the wireless network for the station.

An access point (AP) is an entity that provides a connection to a distribution system (DS) via a wireless medium for its associated station. In the infrastructure BSS, communication between non-AP stations is performed via an AP. However, when a direct link is established, direct communication is possible between non-AP stations. In the present invention, the AP is used as a concept including a PCP (Personal BSS Coordination Point), and broadly includes a central controller, a base station (BS), a node-B, a base transceiver system (BTS) Controller, and the like. In the present invention, an AP may also be referred to as a base radio communication terminal. The base radio communication terminal is broadly referred to as an AP, a base station, an eNode (eNodeB) and a transmission point (TP) . In addition, the base wireless communication terminal may include various types of wireless communication terminals that allocate communication medium resources in communication with a plurality of wireless communication terminals and perform scheduling.

A plurality of infrastructure BSSs may be interconnected via a distribution system (DS). At this time, a plurality of BSSs connected through a distribution system is called an extended service set (ESS).

2 illustrates an independent BSS that is a wireless LAN system according to another embodiment of the present invention. In the embodiment of FIG. 2, the same or corresponding parts as those of the embodiment of FIG. 1 are not described.

Since the BSS 3 shown in FIG. 2 is an independent BSS and does not include an AP, all the stations STA6 and STA7 are not connected to the AP. An independent BSS is not allowed to connect to the distribution system and forms a self-contained network. In the independent BSS, each of the stations STA6 and STA7 can be directly connected to each other.

3 is a block diagram showing a configuration of a wireless communication terminal (or station, STA 100) according to an embodiment of the present invention.

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

First, the transceiver unit 120 transmits and receives a wireless signal such as a wireless LAN packet, and may be installed in the station 100 or externally. According to the embodiment, the transceiver 120 may include at least one transceiver module using different frequency bands. For example, the transceiver 120 may include transmit and receive modules of different frequency bands such as 2.4 GHz, 5 GHz, and 60 GHz. According to one embodiment, the station 100 may include a transmission / reception module using a frequency band of 6 GHz or more and a transmission / reception module using a frequency band of 6 GHz or less. Each of the transmission / reception modules can 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 unit 120 may operate only one transceiver module at a time or may operate a plurality of transceiver modules at the same time according to the performance and requirements of the station 100. [ When the station 100 includes a plurality of transmission / reception modules, each of the transmission / reception modules 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 can receive user input using various input means, and the processor 110 can control the station 100 based on the received user input. Also, the user interface unit 140 may perform output based on the instruction 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 a 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 types of data. Such a control program may include an access program required for the station 100 to make an access to an AP or an external station.

The processor 110 of the present invention can execute various commands or programs and process data inside the station 100. [ In addition, the processor 110 controls each unit of the above-described station 100, and can control data transmission / reception between the units. According to an embodiment of the present invention, the processor 110 may execute a program for connection with an AP stored in the memory 160, and may receive a communication setup message transmitted by the AP. In addition, the processor 110 can read information on the priority condition of the station 100 included in the communication setup message, and request a connection 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 a main control unit of the station 100 and may include a control unit for controlling a part of the station 100 such as the transmission and reception unit 120, It can also point to. That is, the processor 110 may be a modem or a modulator and / or a demodulator for modulating and demodulating a radio signal transmitted and received from the transceiver 120. The processor 110 controls various operations of transmitting and receiving radio signals of the station 100 according to the embodiment of the present invention. Specific embodiments thereof will be described later.

The station 100 shown in FIG. 3 is a block diagram according to an embodiment of the present invention, and the blocks separately displayed are logically distinguishable from the elements of the device. Thus, the elements of the device described above can be mounted as one chip or as a plurality of chips depending on the design of the device. For example, the processor 110 and the transceiver 120 may be integrated into one chip or may be implemented as a separate chip. In some embodiments of the present invention, some components of the station 100, such as the user interface 140 and the display unit 150, may be optionally provided in the station 100.

4 is a block diagram illustrating a configuration of an access point (AP) 200 according to an embodiment of the present invention.

As shown, the AP 200 according to the embodiment of the present invention may include a processor 210, a transceiver 220, and a memory 260. In FIG. 4, the same or corresponding parts as those of the station 100 of FIG. 3 among the configurations of the AP 200 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. 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 of 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 more and a transmission / reception module using a frequency band of 6 GHz or less. Each of the transmission / reception modules can perform wireless communication with the station according to the wireless LAN standard of the frequency band supported by the transmission / reception module. The transceiver 220 may operate only one transceiver module at a time or operate a plurality of transceiver modules at the same time 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 the connection of the station. In addition, the processor 210 controls each unit of the AP 200, and can control data transmission / reception between the units. According to an embodiment of the present invention, processor 210 may execute a program for connection with a station stored in memory 260 and may transmit a communication setup message for one or more stations. At this time, the communication setup message may include information on the connection preference condition of each station. In addition, the processor 210 performs connection setup according to a connection request of the station. According to an embodiment, the processor 210 may be a modem or a modulator and / or a demodulator for modulating and demodulating a radio signal transmitted / received from the transceiver 220. The processor 210 controls various operations of transmitting and receiving radio signals of the AP 200 according to an embodiment of the present invention. Specific embodiments thereof will be described later.

5 is a diagram illustrating a process in which a wireless communication terminal (STA) establishes a link with an access point (AP).

Referring to FIG. 5, the link between the STA 100 and the AP 200 is 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 a BSS operated by the AP 200. As a method for performing scanning, a passive scanning method in which information is acquired using only a beacon message (S101) periodically transmitted by the AP 200 and a passive scanning method in which the STA 100 transmits a probe request there is an active scanning method in which a probe request is transmitted (S103), a probe response is received from the AP (S105) and access information is acquired.

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

On the other hand, the 802.1X-based authentication step S111 and the IP address acquisition step S113 through DHCP can be performed. 5, the authentication server 300 is a server that processes STA 100 and 802.1X-based authentication, and may be physically coupled to the AP 200 or exist as a separate server.

6 is a diagram illustrating a passive scanning method of a wireless communication terminal (STA) according to an embodiment of the present invention.

Referring to FIG. 6, a first STA 100 according to an exemplary embodiment of the present invention receives a beacon message periodically transmitted from a neighboring first AP 201 and a second AP 202, .

7 is a diagram illustrating an active scanning method of a wireless communication terminal (STA) according to an embodiment of the present invention.

Referring to FIG. 7, the first STA 100 according to the present invention transmits a probe request message to acquire information of a neighboring AP and transmits a corresponding probe response message to the first AP 201 2 AP 202 and acquires the wireless access information of the APs.

According to the embodiment of the present invention, the performance of the wireless LAN system can be improved by sharing the communication environment information of the user (user device or wireless communication terminal). Here, the communication environment information may be local information detected by the wireless communication terminal. A detailed description of the communication environment information or the local information will be described when explaining Fig.

The multiple access technology of wireless LAN is based on Carrier Sensing Multiple Access (CSMA). That is, when two or more radio signals are transmitted in a specific area, the two radio signals may cause a collision or interference, which causes performance deterioration of the system. The CSMA technique may be used to prevent collision or interference of such signals, so that transmissions for one radio signal within the particular region (when the transmission time and frequency band of the signal are the same or similar to each other) . This can serve as a limiting factor for the performance of the WLAN.

In order to solve such a problem, in the IEEE 802.11ac standard, a Downlink Multi-user Multiple Input (MIMO) communication technique in which an access point simultaneously transmits to multiple users using multiple antennas in a downlink process transmitted to users and Multiple Output, DL-MU-MIMO). However, this technology relates to multiple communication within one BSS, and when transmitting a radio signal according to the downlink MU-MIMO scheme in a specific BSS, it is possible to restrict the radio communication of an adjacent BSS. In addition, as the number of users participating in wireless communication increases, the density of wireless signals in a specific area or area increases, and the increase in the density of the wireless signals may lead to a large deterioration in the wireless LAN system. In addition, the IEEE 802.11ax standard, which is currently under discussion, introduces an uplink MUI (MIMO-MIMO) and introduces Orthogonal Frequency Division Multiple Access (OFDMA) to all the uplink and downlink. to be. If the technique is realized, the number of users communicating with one access point is expected to increase further. Accordingly, in a high-density wireless LAN and a multi-user communication environment, communication of one BSS may restrict communication of other BSSs in the vicinity, and in spite of benefits due to multi-user technology application, The performance of the entire wireless LAN system may deteriorate.

Such performance degradation is highly dependent on the local location of the wireless communication terminals participating in the communication. For example, in the case of a wireless communication terminal that is remote or isolated from another BSS, it does not restrict the communication of the other BSS, whether participating in the communication or not. However, when a wireless communication terminal transmits or receives a wireless signal in an environment in which a plurality of BSSs are overlapped, the transmission and reception of the wireless signal affect all the overlapped BSSs, and accordingly, The communication of the terminal can be restricted. Therefore, in the case of multi-user communication, when the wireless communication terminals participating in the communication are located over a wide area, it can affect the BSS in a wide area of the area. Conversely, when the wireless communication terminals are located in a specific area (for example, when the wireless communication terminals communicating with each other are locally located in a narrow warehouse), a multi-user communication signal by the wireless communication terminals reaches Is similar to the range that the radio signal of the single radio communication terminal reaches.

According to the embodiment of the present invention, the access point can collect the communication environment information (or local information) sensed by each wireless communication terminal and improve the performance of the entire system by using the collected communication environment information Space recycling can be increased. According to a preferred embodiment of the present invention, an access point can reduce influence on communication of other BSS by selecting a wireless communication terminal participating in wireless communication based on the communication environment information.

FIG. 8 is a diagram illustrating a multiple BSS environment (or a superposed BSS environment) according to an embodiment of the present invention. In FIG. 8, circles shown by three dashed lines represent the respective BSSs (BSS-1, BSS-2, BSS-3), and circles shown by the dotted lines represent the range of the STA's wireless signal. 8, AP-1, STA-1-1 to STA-1-5 are included in BSS-1, AP-2, STA-2-1 to STA-2-3 are included in BSS-2 , BSS-3 includes AP-3, STA-3-1 to STA-3-3. 8, the BSSs are superimposed on each other.

For example, it can be assumed that AP-1 of BSS-1 transmits a radio signal to two STAs using downlink MU-MIMO. At this time, if AP-1 selects {STA-1-2, STA-1-4} to transmit a radio signal, STA-2-1 of BSS-2 and STA- 3-3 of BSS- The resource unit of the same or similar frequency band used by the AP-1 becomes unavailable. As another example, when AP-1 selects {STA-1-2, STA-1-3} and transmits a wireless signal to the two STAs, the transmission of such a wireless signal only affects BSS-3 , And BSS-2.

That is, depending on the relative positions of the users (or the wireless communication terminals), the degree of influence on the other BSSs in the vicinity is changed. From this point of view, information such as which BSS exists in the vicinity of a specific wireless communication terminal or which wireless communication terminal exists can be treated as important. The wireless LAN system can be operated efficiently by selecting a wireless communication terminal to participate in wireless communication based on the information.

According to an embodiment of the present invention, each wireless communication terminal can sense communication environment information indicating a communication environment. Here, the communication environment information may be local information detected by the wireless communication terminal. According to an embodiment of the present invention, the geographical information may mean a numeric value / value / information that changes when a relative positional relationship of a wireless communication terminal with respect to another wireless communication device (another AP, another STA, etc.) is changed.

According to an embodiment of the present invention, the communication environment information may include a BSS distinguisher or a device distinguisher included in the wireless signal received by the wireless communication terminal, and intensity information of the wireless signal. Here, the BSS distinguisher is information for distinguishing a BSS to which the wireless communication device that transmitted the wireless signal belongs, and the device identifier may be information for distinguishing the wireless communication device that transmitted the wireless signal. According to a preferred embodiment of the present invention, the BSS distinguisher includes BSS color information of the access point, the device identifier includes an association ID (ID) of the wireless communication terminal, and the strength information of the wireless signal is RSSI Strength Index).

The wireless communication terminal can acquire the BSS differentiator through a wireless signal or active / passive scanning transmitted by another access point belonging to the neighboring BSS or another wireless communication terminal. For example, when the access point requests the communication environment information, the access point can perform active / passive scanning in response to the request, thereby sensing other access points existing in the vicinity (or capable of communication). In the process of scanning the other access point, BSS discriminator information such as BSS color related to the BSS to which the access point belongs can be obtained. For example, STA-1-3 in FIG. 8 can receive radio signals transmitted by AP-1 and AP-2 through active / passive scanning, and AP-1 and AP-2 Gt; BSS < / RTI > The wireless communication terminal reports the obtained BSS differentiator information to the access point so that the access point can obtain the latest information on the BSS around the wireless communication terminal. Alternatively, the wireless communication terminal can receive the BSS differentiator detected by the other wireless communication terminal from other peripheral wireless communication terminals, and can transmit the received BSS differentiator to the access point in response to the request.

On the other hand, the wireless communication terminal can extract a device distinguisher from a wireless signal transmitted by another access point or another wireless communication terminal, or can receive a device distinguisher from another wireless communication terminal.

The wireless communication terminal can acquire the intensity of the wireless signal including the BSS distinguisher or the device identifier as one kind of communication environment information in the process of acquiring the BSS distinguisher or the device distinguisher.

As described above, the communication environment information may be local information. That is, the distance or the relative positional relationship between the wireless communication terminal and another wireless communication device in the vicinity may be changed when the area or space where the wireless communication terminal is located is changed. If a distance or a relative positional relationship between the wireless communication terminal and another wireless communication device in the vicinity is changed, the wireless signal received by the wireless communication terminal may also be changed. For example, it can be assumed in FIG. 8 that the STA-3-1 can receive only the radio signal of the AP-3. In this case, when STA-3-1 moves to the position of STA-1-4, STA-3-1 not only AP-1 and AP-2 but also STA-1-4, STA- 1, and STA-3-1 can obtain a BSS distinguisher or a device distinguisher of each of the above-mentioned devices from the wireless signal. On the other hand, if the area or the space where the wireless communication terminal is located is changed, the intensity of the wireless signal received by the wireless communication terminal may also be changed. For example, STA-1-3 in FIG. 8 can receive a radio signal transmitted by an adjacent STA-3-3. If the STA-1-3 is moved to the STA-3-1 position, the STA-1-3 can recognize that the strength of the STA-3- radio signal is too weak to be received.

According to a preferred embodiment of the present invention, an access point that receives communication environment information from each wireless communication terminal determines a distance or a relative positional relationship between each wireless communication terminal and another wireless communication terminal based on the received communication environment information . Here, the distance may be determined based on the similarity of the intensity information of the BSS distinguisher, the device distinguisher, or the radio signal sensed by each of the wireless communication terminals.

Here, the degree of similarity may be calculated in various manners. For example, the access point can determine the degree of similarity based on the degree of duplication of the list of BSS distinguisher or device distinguisher reported by a specific wireless communication terminal with the list of BSS distinguisher or device distinguisher reported by other wireless communication terminals If the similarity of two lists is high, it can be determined that the distance between two wireless communication terminals is close.

For example, with reference to FIG. 8, the following situation can be assumed.

- STA-1-1 receives STA-1-2 and STA-1-3 related device distinguisher with weak intensity

- STA-1-2 receives radio signals including STA-1-3 and STA-3-3 related device discriminator and AP-3 related BSS discriminator at strong intensity and includes STA-1-1 related device discriminator Receive a radio signal at a weak intensity

- STA-1-3 receives radio signals including STA-1-3 and STA-3-3 related device discriminator and AP-3 related BSS discriminator at strong intensity and includes STA-1-1 related device discriminator Receive a radio signal at a weak intensity

The AP-1 can receive the communication environment information detected by the STA-1-3 or the STA-1-3. In this case, since AP-1 has detected the same STA-3-3 related device distinguisher and the same AP-3 related BSS distinguisher, STA-1-2 and STA- 3 are close to each other. In addition, if the STA-1-2 and the STA-1-3 receive the radio signal including the STA-1-1 related device identifier at similar strengths, the STA-1-2 and the STA- It can be determined that the distance is very close. On the other hand, the AP-1 can recognize that the communication environment information reported by the STA-1-1 is similar to the communication environment information reported by the STA-1-2 and the STA-1-3, -1 can be determined to be far from the STA-1-2 and the STA-1-3. Also, the access point determines that STA-1-2 and STA-1-3 are located in an area adjacent to AP-3, and STA-1-1 is not related to the BSS overlap situation.

Meanwhile, according to the embodiment of the present invention, the access point can classify the wireless communication terminals into at least one group based on the discriminated distance. In the above example, STA-1-2 and STA-1-3 reporting similar communication environment information can be judged to be close to each other, so that STA-1-2 and STA-1-3 are identical Group. On the other hand, STA-1-1 reporting completely different communication environment information can be classified as a group different from STA-1-2 and STA-1-3. That is, the access point can recognize that the STA-1-1 is locally separated from the STA-1-2 and the STA-1-3.

The access point may transmit a radio signal to a plurality of wireless communication terminals included in the same one of the plurality of groups, such as a multi-user multiple input / multiple output (MU-MIMO). In the above example, the access point AP-1 can perform MU-MIMO for STA-1-2 and STA-1-3 included in the same group. That is, the AP-1 does not perform the MU-MIMO with the other STA-1-4 or the STA-1-5, but the STA-1-2 included in the same group as the STA- And the MU-MIMO, it is possible to minimize the influence of the AP-2, the STA-2-1, and the STA2-2 of the BSS-2 on the wireless communication, and as a result, the space recycling of the entire system can be increased.

Next, consideration must be given to a method of transmitting the communication environment information acquired by each wireless communication terminal to the access point. According to an embodiment of the present invention, an access point can transmit a trigger signal for requesting transmission of communication environment information to each wireless communication terminal, and the communication environment information corresponding to the trigger signal from each wireless communication terminal Lt; / RTI > Hereinafter, the transmission method will be described with reference to FIG. 9 through FIG.

9 is a diagram illustrating a method by which a wireless communication terminal transmits communication environment information to an access point according to an embodiment of the present invention. 9 is a diagram showing a radio signal transmitted from each radio communication apparatus according to the progress of time. In FIG. 9, the radio signals of the STAs are shown as rectangles, and the vertical axis of the rectangles represents frequency resources used by the radio signals and the horizontal axis represents time resources used by the radio signals. 9, BSS-Color- (number) and AID- (number) indicate BSS color information and AID detected by STA- (number).

According to an embodiment of the present invention, a trigger signal transmitted by an access point may include communication resource information allocated for transmission of the communication environment information, and each of the wireless communication terminals, based on the allocated communication resource information, The communication environment information can be transmitted.

More specifically, the access point AP-1 transmits to the wireless communication terminals STA-1 to STA-3 belonging to the same BSS the wireless communication resources for UL-MU- (Or a resource unit), and may include information related to the allocation of the wireless communication resources in the trigger signal. According to FIG. 9, STA-1 is allocated resource 1, STA-2 is allocated resource 2, STA-3 is allocated resource 3, and after the trigger signal is concurrently or sequentially The communication environment information can be transmitted.

10 is a diagram illustrating a method in which a wireless communication terminal transmits communication environment information to an access point according to another embodiment of the present invention. 10 is similar to that of FIG. 9, so that detailed description of each item will be omitted.

According to FIG. 10, the access point can transmit a trigger signal in a broadcasting manner, and can receive communication environment information from each wireless communication terminal that has made random access in response to the trigger signal.

In more detail, the access point AP-1 does not allocate wireless communication resources to the respective wireless communication terminals STA-1 to STA-4, but instead transmits the communication environment information through the uplink random access method A requesting trigger signal can be transmitted. Accordingly, the wireless communication terminal can transmit the communication environment information to the access point using any wireless communication resource (or resource unit) corresponding to the trigger signal. Since the wireless communication resources used by each wireless communication terminal are arbitrarily determined, a plurality of wireless communication terminals use the same wireless communication resource, so that a signal collision or interference may occur. Correspondingly, the access point may broadcast at least a portion of the wireless communication terminals, and may broadcast a trigger signal requesting the selected wireless communication terminals to report the communication environment information. This reduces the probability of collision or interference of the communication environment information of the wireless communication terminal. Alternatively, the access point may transmit a trigger signal requesting all wireless communication terminals receiving the trigger signal to report the communication environment information for efficiency and promptness of report of communication environment information. 9, the access point allocates wireless communication resources to the STA-1 and the STA-2, and transmits the trigger signal to the STA- 1 and STA-2 may request to transmit the communication environment information.

Meanwhile, according to a preferred embodiment of the present invention, the access point may select at least one BSS distinguisher or device distinguisher, and the trigger signal may be a radio signal that senses a radio signal including the selected BSS distinguisher or the selected device distinguisher And may be a signal requesting the communication terminal to transmit the communication environment information. According to FIG. 10, the access point AP-1 broadcasts a trigger signal for requesting communication environment information, and the trigger signal is a signal requesting reporting of some of the wireless communication terminals STA-1 to STA-3. Alternatively, the trigger signal may be a signal transmitted only to some of the wireless communication terminals STA-1 to STA-3. Also, the access point AP-1 can request reporting of the communication environment information of the wireless communication terminal which senses the BSS discriminator whose BSS color is RED through the trigger signal. Accordingly, only the STA-1 and the STA-2 among the wireless communication terminals can report the communication environment information. At this time, the STA-1 and the STA-2 can select any wireless communication resource and perform the reporting.

Next, a screening method for communication environment information sensed by the wireless communication terminal will be described.

As described above, when considering the tendency of the wireless LAN to be densified, the number of communication environment information that the wireless communication terminal can acquire can be very large. The access point can classify each wireless communication terminal into at least one group based on the secured communication environment information when a certain amount of communication environment information is secured. In addition, when the grouping is completed, The above communication environment information may be unnecessary or meaningless information. That is, it is inefficient to transmit all communication environment information sensed by the wireless communication terminal to the access point, and unnecessary loss of wireless communication resources may occur due to reporting of unnecessary communication environment information.

Correspondingly, according to a preferred embodiment of the present invention, the communication environment information is selected by the wireless communication terminal based on the time of receiving the wireless signal (including the communication environment information) or the intensity information of the wireless signal Lt; / RTI > In more detail, the wireless communication terminal can perform selection based on temporal sorting or wireless signal intensity ranking or selection based on a specific wireless signal strength threshold for communication environment information, and each of the sorting methods is redundant Lt; / RTI >

First, temporal selection is a method of not selecting the communication environment information of the radio signal received by the radio communication terminal before a predetermined time from the current time in the communication environment information. That is, among the information held by the wireless communication terminal before the wireless communication terminal receives the request for the communication environment information, it does not transmit the old information before the specific time in time to the access point. This means that the wireless communication terminal to be. That is, there is a high possibility that the position of the wireless communication terminal changes over time, and accordingly, the communication environment information sensed long before by the wireless communication terminal may not be suitable for the current situation. If the communication environment information detected long before is transmitted to the access point, the access point can perform an erroneous grouping based on the old communication environment information.

According to another embodiment of the present invention, the wireless communication terminal can add timer information for validity confirmation to the detected individual communication environment information. Timer information for validation may have a certain valid time value. Accordingly, the specific effective time value is subtracted according to the time from immediately after each communication environment information is detected, and when the effective time value becomes 0, the corresponding communication environment information can be treated as invalid. The valid time value may be determined based on a change in the communication environment information sensed by the wireless communication terminal. That is, when the wireless communication terminal does not move or the wireless communication environment around the wireless communication terminal is static, there is little possibility that the intensity of the BSS distinguisher, the device distinguisher, and the wireless signal included in the communication environment information is changed. The effective time value may be increased when the degree of change of the communication environment information is low. On the other hand, if the degree of change of the communication environment information is high due to the continuous movement of the wireless communication terminal or the dynamic change of the surrounding wireless communication environment, the effective time value can be reduced. When the effective time value is decreased, the wireless communication terminal transmits only the relatively latest communication environment information to the access point, so that the access point can immediately confirm the change of the wireless communication environment around the wireless communication terminal.

According to another embodiment of the present invention, the communication environment information of the radio signal received by the access point before the preset time from the current time of the communication environment information transmitted by the wireless communication terminal is transmitted between the wireless communication terminals It may not be used for distance calculation and group classification.

As described above, there is a method of referring to the strength of a radio signal including communication environment information by another selection method of communication environment information. At this time, the wireless communication terminal can perform selection based on a relative criterion with respect to the intensity or selection based on an absolute criterion.

According to the embodiment of the present invention, the order of strength of the radio signal is determined based on the strength information of the radio signal received by the radio communication terminal, The communication environment information of the radio signal whose strength ranking of the radio signal is within a predetermined rank can be selected. For example, it can be assumed that there are four access points around a wireless communication terminal. The wireless communication terminal may receive a wireless signal including a BSS distinguisher from each access point and recognize the order of the wireless signal. If the predetermined order is 3, the strength information of the radio signal having the fourth strength and the BSS differentiator included in the radio signal can not be sorted and thus can not be transmitted to the access point. According to this method, the wireless communication terminal can report a certain number (predetermined order) of communication environment information.

As the intensity of the signal increases, an access point related to the BSS distinguisher included in the wireless signal or another wireless communication terminal related to the device identifier included in the wireless signal is located at a distance from the wireless communication terminal that senses the wireless signal . Therefore, even if only the communication environment information related to the radio signal having the high-order intensity is used, the access point can easily perform distance and group classification between the respective wireless communication terminals. Further, as the strength of the signal is weak, it is difficult to confirm the geographical positional relationship between the access point or other wireless communication terminal related to the wireless signal and the wireless communication terminal that senses the wireless signal. Therefore, it can be estimated that the importance of the communication environment information related to the radio signal with weak signal strength is low.

Selection based on the absolute reference of the radio signal strength is a method in which the communication environment information of the radio signal whose intensity of the radio signal is equal to or greater than a preset signal strength limit value is selected. For the same reason as the selection based on the relative criterion, the access point or the wireless communication terminal related to the wireless signal having a weak signal strength may be determined to be distant from the wireless communication terminal sensing the wireless signal. That is, the weak signal-related communication environment information is transmitted to the access point, and the other weak-signal-related access point or other wireless communication terminal is determined to be distant from the wireless communication terminal transmitting the communication environment information Do. Therefore, it may be efficient that the wireless environment-related communication environment information whose signal strength is less than a predetermined signal strength limit value is not transmitted to the access point.

The above-described configurations will be described in terms of a wireless communication terminal as follows.

The wireless communication terminal receives the wireless signal transmitted from the external wireless communication device, extracts the communication environment information indicating the communication environment from the wireless signal, and transmits the communication environment information to the access point included in the same BSS (Basic Service Set) The communication environment information can be transmitted. When the wireless communication terminal receives the wireless signal from the access point, the wireless communication terminal can receive the wireless signal transmitted by the access point based on the group. Here, the group may be one in which the access point determines the distance between each wireless communication terminal in the BSS based on the communication environment information, and classifies each wireless communication terminal in the BSS based on the determined distance have.

The distinction between the wireless communication terminals based on the communication environment information, the grouping based on the distance, and the selection of the communication environment information by the wireless communication terminal have been described in the preceding paragraph.

On the other hand, because of the nature of the license-exempted band, access points can be easily installed by anyone and the use of the access points is easy, so that the communication ranges of a large number of BSSs are likely to overlap each other. However, as described above, interference due to other BSSs may degrade the performance of the entire WLAN system (in particular, when a basic access method is used) due to the characteristics of a wireless LAN using the signal detection multiple access scheme, Given the current trend of increasingly dense LANs, this is a big problem.

In another way corresponding to this, cooperation between BSSs through wireless communication terminals existing in an intersection area of the BSS communication range in a BSS overlapping environment or a method of controlling transmission or interference of a wireless signal through cooperation between access points can be considered have. In addition, an OFDMA technique in the IEEE 802.11ax standard, which is currently under discussion, can also be considered. According to the OFDMA technique, since a plurality of wireless communication terminals divide and use the 20 MHz frequency band, competition of a plurality of wireless communication terminals belonging to one BSS can be mitigated and collision between wireless signals can be reduced, Can be improved. In addition, the use of OFDMA technology can reduce interference between multiple BSSs and increase space recycling.

11 is a diagram illustrating a multiple BSS environment according to another embodiment of the present invention.

Referring to FIG. 11, AP-1 may transmit a radio signal to STA-1 and AP-2 may transmit a radio signal to STA-2. However, since both STA-1 and STA-2 are within the transmission range of AP-1 and AP-2, if the transmission of the two radio signals is not temporally separated, the two radio signals may collide. As a result, neither STA can decode the radio signal transmitted from each AP.

12 is a diagram illustrating an embodiment of the present invention in which an OFDMA scheme is applied to a multiple BSS environment.

FIG. 12 shows the same situation as FIG. 11, but unlike FIG. 11, AP-1 and AP-2 do not use the 20 MHz fundamental frequency band. Referring to FIG. 12, when the AP-1 transmits a radio signal to the STA-1, a higher band (or a lower band) of the basic frequency band is used and when the AP- The lower band (or higher band) may be used. Accordingly, the radio signals transmitted to the STA-1 and the STA-2 are not separated in the time domain but can be separated from each other in the frequency domain. That is, each AP can transmit the two wireless signals in the same time zone by performing wireless communication using different resource units. If such a scheme is used, the basic access scheme can enjoy a collision reducing effect of a radio signal.

When the embodiment of FIG. 12 is utilized, the virtual access method for solving the hidden node problem can enjoy the effect of increasing the space recycling, and consequently, the system performance can be greatly improved. That is, in the conventional method, the communication resources of a specific frequency band are occupied by the wireless communication with respect to one wireless communication terminal, and the remaining wireless communication terminals transmit the corresponding communication resource (NAV) for a time determined by a network allocation vector Can not be used. However, when the specific frequency band is divided and can be used for wireless communication with respect to different wireless communication terminals, the frequency of communication resource access restriction by the network allocation vector is reduced compared to the existing system, Wireless communication with respect to the wireless communication terminal of the wireless communication terminal can be performed. In particular, according to the method of FIG. 12, the performance of the wireless LAN system can be greatly improved when a wireless signal is transmitted to the wireless communication terminals located at the edge of the BSS. It is more likely that the wireless communication terminal located at the edge of the BSS than the wireless communication terminal located at the center of the BSS experiences signal interference by the wireless communication terminal of the other BSS in an overlapping BSS. This is because the problem can be solved.

However, there is a problem to be considered in connection with the transmission method. First, in the case of the data field of the radio signal, transmission can be performed without collision through resource unit allocation of different frequency bands as described above. However, in the case of a preamble of a radio signal, the signal is transmitted using the entire 20 MHz band. Therefore, when the data field of the radio signal is simultaneously transmitted, a collision between the preamble of AP-1 and the preamble of AP-2 may occur. To solve this problem, the following communication method can be considered.

FIG. 13 shows a transmission method of a radio signal according to an embodiment of the present invention. In particular, FIG. 13 may be an illustration of how each of the wireless communication devices operates in the context of FIG. Accordingly, AP-1 and STA-1 belong to BSS-1, AP-2 and STA-2 belong to BSS-2, and STA-1 and STA-2 exist in a region where BSS overlaps.

According to the embodiment of the present invention, when the wireless communication terminal STA-1 receives a wireless signal from the access point AP-1, the wireless communication terminal STA-1 transmits the wireless signal of another BSS (BSS of AP- A case where a signal by the device (AP-2 or STA-2) is received may occur. For example, the STA-1 may not correctly receive or decode the AP-1's radio signal due to interference or collision with AP-2 or STA-2 of BSS-2. When this situation occurs, the wireless communication terminal STA-1 receives the access point AP-1 included in the access point AP-1 and the other BSS (BSS-2 of FIG. 11 or 12) Lt; RTI ID = 0.0 > a < / RTI > request to share wireless communication related information. Since the information of each wireless communication apparatus is shared or a unified preamble including the same information can be generated according to the following process, a signal requesting the sharing of the information is a coordination request frame It may be named. Alternatively, the integration request signal may be a signal that the wireless communication terminal (STA-1) requests simultaneous transmission (or cooperative transmission or cooperative transmission) of the data field of the wireless signal. Here, since the wireless communication terminal STA-1 or STA-2 exists at a position capable of receiving the signals of the access points AP-1 and AP-2, the wireless communication terminal STA-1 or STA-2 can serve as a relay wireless communication terminal, May be transmitted to both access points AP-1 and AP-2. The access points AP-1 and AP-2 receiving this signal can share information or exchange information related to wireless communication held by each access point by relaying the STA-1 as a relay wireless communication terminal. Here, the information related to the wireless communication includes at least one of resource unit information, preamble configuration information (or information for preamble integration or a set of information included in the preamble), and radio signal transmission timing information, . ≪ / RTI > That is, information related to the wireless communication of the access point AP-1 can be transmitted to the access point AP-2 through the relay wireless communication terminal STA-1, and information related to the wireless communication of the access point AP- May be transmitted to access point AP-1 via STA-1. At this time, a wireless signal including information related to the wireless communication of the access points AP-1 and AP-2 can be transmitted to the relay wireless communication terminal STA-1 through the general downlink transmission, and the relay wireless communication terminal STA- The received radio signal may be transmitted to each access point through normal uplink transmission. Alternatively, the relay wireless communication terminal STA-1 can transmit the wireless signal through the uplink random access method. Meanwhile, other wireless communication terminals STA-2 may participate in the information sharing process, and information related to wireless communication of the other wireless communication terminals STA-2 may also be shared. According to another embodiment of the present invention, in the information sharing process, a frequency band to be used by each access point and resource unit information according to the frequency band may be shared, and a frequency band to be used by each access point and a resource An agreement on the unit may proceed. For example, each access point can calculate the number of wireless communication terminals capable of receiving a signal of an external access point, which is an access point of another BSS among the wireless communication terminals in its BSS, based on the communication environment information. The access point can share the number of wireless communication terminals capable of receiving the signal of the external access point in the information sharing process and the access point having a large number of wireless communication terminals capable of receiving signals of the external access point It can be agreed to use a resource unit of a high frequency band. Or simply, when one access point arbitrarily decides to use a resource unit of a particular frequency band, it may be agreed that another access point uses the remaining resource units of the frequency band. However, the method of summing up the resource units is not limited thereto. On the other hand, the preamble includes information necessary for decoding a radio signal, and in particular, information related to modulation or demodulation of a radio signal of each access point. In the information sharing process, each access point may share the information of the preamble and agree to modulate or demodulate the radio signal in the same manner. At this time, the modulation or demodulation method of the radio signal to be included in the preamble may be a method determined arbitrarily by one of the access points AP-1 and AP-2. Also, in the information sharing process, radio signal transmission timing information of each access point can be determined, and in the following process, each access point can transmit a radio signal based on the radio signal transmission timing.

When the sharing of this information is completed, the wireless communication terminal STA-1 can transmit a coordination trigger frame requesting the start of wireless signal transmission of each access point, Signal to the destination wireless communication terminal (STA-1 in case of AP-1 and STA-2 in case of AP-2). At this time, each of the access points AP-1 and AP-2 can generate the same preamble based on the information related to the wireless communication shared in the previous information transmission process, and can transmit the wireless signal using the same preamble. Here, since access points AP-1 and AP-2 perform modulation or demodulation of a radio signal in the same manner, the random preamble generated at each access point is the same. 13, access point AP-1 performs communication through a resource unit of a higher frequency band than STA-1, access point AP-2 transmits a resource unit of lower frequency band to STA- And performs communication. Information related to the communication of each access point may be included in the HE integrated preamble of FIG. According to a preferred embodiment of the present invention, information necessary for communication between the access point AP-1 and the STA-1 (frequency band and corresponding resource unit and the like) and information required for communication between the access point AP-2 and the STA- The two access points can generate the HE integrated preamble having the same contents because the information is mutually shared in the previous information sharing process.

The access point AP-1 can transmit the same preamble and data field transmitted to the access point STA-1 in synchronization with the radio signal transmission of the APA-2. At this time, the synchronization of the radio signal transmission can be performed by referring to the radio signal transmission timing shared in the information sharing process. The access points AP-1 and AP-2 can transmit a preamble (a laggas preamble and an HE integrated preamble) at the same time. Since the preambles are the same, the content included in the preamble does not collide with each other, And can be decrypted in the wireless communication terminals STA-1 and STA-2. Each of the wireless communication terminals STA-1 and STA-2 can individually receive data fields transmitted using resource units according to different frequency bands after the preamble without signal interference.

According to the method of FIG. 13, since identical preambles are generated, they can be named as an union preamble method.

FIG. 14 shows a transmission method of a radio signal according to another embodiment of the present invention.

14, the wireless communication terminal STA-1 can transmit an integration request signal in the same way as the integrated preamble system of FIG. 13, and the access points AP-1 and AP-2 transmit the wireless communication terminal STA- (Resource unit information, wireless signal transmission timing information, preamble configuration information, and the like) related to wireless communication by using the wireless communication terminal as a communication terminal. 14, the length information (or time information corresponding to the length of the preamble) of the preamble (the preamble and the HE integrated preamble) of the two access points AP-1 and AP-2 can be shared have. In addition, in the information sharing process, the transmission order of the preamble of each access point AP-1 and the preamble transmission timing and data field transmission timing of each access point can be agreed. Here, the preamble transmission timing and the data field transmission timing of each access point may be information included in the radio signal transmission timing information described above.

According to the embodiment of the present invention, the preamble transmission order of the access point is arbitrarily determined, and the first preamble transmission timing (t1), which is the preamble transmission timing of the access point transmitting the preamble for the first time, (T1 = r0 + s1) after a specific time (s1, e.g., 0 to 6 us, time for protecting other radio signals) after the trigger signal reception (r0). The second preamble transmission timing (t2), which is the preamble transmission timing of the access point transmitting the preamble in the next order, is a time p1 corresponding to the length of the preamble transmitted in the first preamble transmission from the first preamble transmission timing (t1) (T2 = t1 + p1 + s2) after a predetermined time (s2, for example, 0 to 10 us, and time for protection of other radio signals). The subsequent preamble transmission timing may be the time corresponding to the length of the immediately preceding preamble from the immediately preceding preamble transmission timing and the time after the specified time (t_n = t_ (n-1) + p_ (n-1) + s2, n Is a natural number of 2 or more). On the other hand, the data field transmission timing may be a time after a specific time elapses after completion of transmission of the last preamble.

When the information sharing process is completed, the wireless communication terminal STA-1 transmits an integrated transmission trigger signal, and each access point can transmit its own preamble in accordance with the agreed order. According to FIG. 14, unlike the case of FIG. 13, the radio signal of each access point can be separated from the preamble and the data field, and the data field can be discontinuously transmitted in the time domain after completion of the preamble transmission. The preamble can be transmitted according to the preamble transmission timing of each access point described above. here. 13, since the HE integrated preambles of the two access points do not overlap with each other, the HE integrated preambles of the access point AP-1 and the access point AP-2 may be different from each other. That is, only the information for communication between the access point AP-1 and the wireless communication terminal STA-1 can be included in the HE integrated preamble of the access point AP-1, and the access point AP-1 And the wireless communication terminal STA-2. After completion of preamble transmission of all access points, each access point can transmit a data field to the destination wireless communication terminal (STA-1 in case of AP-1, STA-2 in case of AP-2) at the same data field transmission timing. In this case, a preamble may be added to the data field. Since the contents of the preamble of the two access points can be configured as described in FIG. 13, the individual wireless communication terminals STA-1 and STA- 2 may each receive a data field to be transmitted to itself.

According to the method of FIG. 14, since the preamble can be separated and transmitted separately from the data field, it can be named as a preamble division method.

15 is a diagram illustrating a radio signal transmission method according to another embodiment of the present invention.

FIG. 15A shows a situation when the access point AP-1 performs wireless communication with two wireless communication terminals STA-1a and STA-1b in the situation of FIG. At this time, the wireless communication terminals STA-1a and STA-1b communicating with the access point AP-1 may be classified into the same group by the access point AP-1. Since the two radio communication terminals STA-1a and STA-1b may cause signal interference with the access point AP-2 or the radio communication terminal STA-2 of the BSS-2, the two radio communication terminals STA-1a and STA- The group to which this belongs can be classified into a signal interference group (dotted circle). Meanwhile, the access point AP-1 can perform downlink MU-MIMO to the wireless communication terminals STA-1a and STA-1b of the signal interference group. At this time, the access point AP- A resource unit in a frequency band different from the frequency band used for communication can be used. As a result, the access point AP-1 can perform downlink MU-MIMO for the two wireless communication terminals STA-1a and STA-1b, and at the same time, the access point AP- It is possible to perform downlink transmission.

14, the access point AP-1 communicates with the two wireless communication terminals STA-1a and STA-1b in the wireless communication (downlink MU- MIMO) is performed. In Fig. 15 (b), the transmission of the integration request signal of the wireless communication terminal STA-1a, the information sharing process of each wireless communication apparatus, the transmission of the integrated transmission trigger signal of the wireless communication terminal STA-1a, The detailed description thereof will be omitted. According to FIG. 15 (a), the access point AP-1 performs downlink MU-MIMO on the two wireless communication terminals STA-1a and STA-1b using resource units corresponding to the higher frequency band. At this time, the MU-MIMO access point AP-1 can simultaneously transmit signals to be transmitted to the wireless communication terminals STA-1a and STA-1b using the same frequency band. Therefore, also in FIG. 15 (b), the access point AP-1 transmits a radio signal to the two radio communication terminals STA-1a and STA-1b by using the resource unit corresponding to the same upper frequency band.

With respect to the embodiment of FIG. 15, another operation method in view of the access point AP-1 will be described as follows.

According to the embodiment of the present invention, the access point AP-1 is connected to the BSS (BSS-1) of the access point based on the communication environment information transmitted by the wireless communication terminals STA-1a and STA- It is possible to identify the external access point AP-2 or the other wireless communication terminal STA-2 of the other BSS (BSS-2). The access point AP-1 transmits resource unit information to the external access point AP-1 through a relay wireless communication terminal (STA-1a or STA-1b) for transmitting and receiving a radio signal with its own AP- From the point AP-2. The reception of the resource unit information may correspond to the information sharing process described above, and the wireless communication related information of the access point AP-1 may be transmitted to the access point AP-2. Then, the access point AP-1 can refer to the resource unit information and select a resource unit in a frequency band different from the frequency band used by the external access point AP-2. Then, the access point AP-1 transmits a signal to the wireless communication terminal (wireless communication terminal) of the signal interference group (dotted circle in FIG. 15) which is a group including the wireless communication terminals causing signal interference with the wireless communication terminals in the other BSS (STA-1a, STA-1b) to transmit the data field of the radio signal.

Here, when the access point AP-1 detects the existence of another BSS or an external access point AP-2 overlapping its own BSS and the other wireless communication terminal STA-2, the access point AP- 1b to the STA-1a or STA-1b, and then the information sharing process, the transmission of the integrated transmission trigger signal, the transmission of the preamble and the data field may be performed.

According to the embodiment of FIG. 15, the MU-MIMO and OFDMA communication schemes can be applied simultaneously in the overlapped BSS environment, thereby maximizing the performance improvement and space recycling of the entire WLAN system.

16 is a diagram illustrating information sharing according to an embodiment of the present invention.

According to the above-described FIG. 13 to FIG. 15, a plurality of BSSs or a plurality of access points can exchange information related to wireless communication through a relay wireless communication terminal. The sharing of this information can be useful for improving the performance of the wireless LAN system. 16, X indicates information transmitted (or shared) between the access point AP-1 and the relay wireless communication terminal STA-1, and Y indicates information transmitted (or shared) between the access point AP- .

Information that can be shared for improving the performance of the wireless LAN system, that is, information included in the X or Y may include the following.

- AIDs of STAs in the intersection of BSS coverage

- Resource unit information to be used when communicating with the STA in the intersection area

- RSSI

- Information (MCS (Modulation and Coding Scheme) level, coding scheme, etc.) for creating an integrated preamble (integrated raw preamble, integrated HE preamble, etc.)

- Time / transmission timing information for wireless signal transmission in the preamble separation scheme

- PPDU length information

- TxOP related information

The above information is not used only for the integrated preamble scheme or the preamble scheme, and the interference amount (or the frequency) of the entire system through interference control and effective scheduling by using information of a plurality of access points or BSSs sharing a communication range with each other, And to reduce signal collisions.

For example, according to the embodiment of FIG. 8, the access point AP-1 can classify the wireless communication terminals into at least one group using the communication environment information. If the communication environment information collected by the access point AP-1 or the MU-MIMO scheduling information for the group and the group are shared by other BSSs or other access points, effective interference control may be performed over a plurality of BSSs . That is, if the above information is shared between BSSs or access points, the following radio signal transmission may be possible.

First Embodiment: When OFDMA is not applied

(Assuming the AP is capable of transmitting wireless signals to both STAs at once)

- AP-1 performs MU-MIMO with STA-1-2 and STA-1-3 with MU-MIMO, AP-2 performs MU-MIMO with STA-2-1 and STA-2-2 at the first radio signal transmission timing, AT -3 is STA-3-1 and STA-3-2 is MU-MIMO

- AP-1 transmits STA-1-4 and STA-1-5 to MU-MIMO, AP-2 transmits STA-2-3 radio signal, AP-3 transmits STA- 3 wireless signal transmission

Second Embodiment: When OFDMA is applied

- MU-MIMO with AP-1 in STA-1-2 (upper frequency band) and STA-1-5 (lower frequency band), AP-2 in STA-2-1 MU-MIMO in STA-2-2 (lower frequency band), AP-3 in STA-3-1 and STA-3-3 (lower frequency band)

17 is a diagram illustrating a control method of a wireless communication terminal and a control method of an access point according to an embodiment of the present invention.

17 (a) relates to a control method of a wireless communication terminal, and the wireless communication terminal can receive a wireless signal transmitted from an external wireless communication apparatus (S110). Here, the external wireless communication device may be a wireless communication terminal or an access point inside the BSS or outside the BSS. Then, the wireless communication terminal can extract the communication environment information indicating the communication environment from the wireless signal (S120). Here, the communication environment information may include a BSS distinguisher or a device distinguisher included in a wireless signal received by the wireless communication terminal, and intensity information of the wireless signal, and the BSS distinguisher may include wireless Is information for distinguishing a BSS to which a communication device belongs, and the device identifier may be information for distinguishing a wireless communication device that has transmitted the wireless signal. The wireless communication terminal transmits the communication environment information to the access point included in the same BSS as the wireless communication terminal itself (S130), and when receiving the wireless signal from the access point, the wireless communication terminal transmits the wireless signal (S140). Here, the group may be one in which the access point determines the distance between each wireless communication terminal in the BSS based on the communication environment information, and classifies the wireless communication terminal in the BSS based on the determined distance .

Meanwhile, although not shown in FIG. 17A, the wireless communication terminal can receive a signal from another BSS wireless communication terminal overlapped with the BSS when receiving a wireless signal from the access point. The wireless communication terminal transmits a signal for requesting sharing of wireless communication related information to the access point and an external access point included in the other BSS, and transmits a resource unit information To the access point. That is, the wireless communication terminal can serve as a relay wireless communication terminal that transmits information between the BSSs in the overlapped BSS or between the access points of the overlapped BSS. Accordingly, the wireless communication terminal can receive (S140) the data field of the wireless signal transmitted from the access point using the resource unit of the frequency band different from the frequency band used by the external access point.

Fig. 17B is a diagram showing a control method of an access point. The access point can receive communication environment information indicating a communication environment from at least one wireless communication terminal (S210). Then, the access point determines the distance between the wireless communication terminals and the other wireless communication terminals based on the received communication environment information (S220), and based on the determined distance, the wireless communication terminal is divided into at least one group (S230), and the transmission of the radio signal may be performed based on the group (S240).

Meanwhile, although not shown in FIG. 17B, the access point can identify an external access point of another BSS that overlaps with the BSS of the access point by referring to the communication environment information, and the access point and the external access Point from the external access point through the relay wireless communication terminal that transmits and receives a wireless signal to the external access point, the resource unit information being information on a resource unit used for transmitting a wireless signal with the external access point, It is possible to select a resource unit of a band different from the frequency band used by the external access point. Accordingly, when the access point transmits a data field of a radio signal to a wireless communication terminal of a signal interference group, which is a group including a wireless communication terminal that causes signal interference with a wireless communication terminal in the BSS of the external access point, The resource unit can be used (S240).

The detailed description related to each step of FIG. 17 is omitted since it has been described with reference to FIGS. 8 to 16. FIG.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. Accordingly, it is to be understood that within the scope of the appended claims, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims (19)

A transmitting and receiving unit for transmitting and receiving a radio signal; And
And a processor for controlling the operation of the transceiver,
The processor comprising:
Receiving communication environment information indicating a communication environment from at least one wireless communication terminal through the transceiver,
Determines a distance between each wireless communication terminal and another wireless communication terminal based on the received communication environment information,
Classifying the at least one wireless communication terminal into at least one group based on the determined distance,
Wherein the transmission of the radio signal through the transceiver is performed on the basis of the group.
The method according to claim 1,
The processor comprising:
Wherein the wireless signal is transmitted to a plurality of wireless communication terminals included in any one of the same group through the transmitting and receiving unit by a multiple user multiple input multiple output method.
3. The method of claim 2,
The communication environment information includes:
A BSS (Basic Service Set) distinguisher or a device distinguisher included in the wireless signal received by the wireless communication terminal, and intensity information of the wireless signal,
Wherein the BSS differentiator is information for distinguishing a BSS to which a wireless communication device that has transmitted the wireless signal belongs, and the device identifier is information for distinguishing the wireless communication device that has transmitted the wireless signal.
The method of claim 3,
The BSS distinguisher includes BSS color information of an access point, the device identifier includes an association ID (AID) of a wireless communication terminal, and the strength information of a wireless signal includes a Received Signal Strength Index (RSSI) Access Point.
The method of claim 3,
The distance,
And the degree of similarity of the intensity information of the BSS distinguisher, the device distinguisher, or the radio signal sensed by each of the wireless communication terminals.
The method of claim 3,
The processor transmits a trigger signal for requesting transmission of the communication environment information to the wireless communication terminal through the transceiver and receives the communication environment information corresponding to the trigger signal from the wireless communication terminal Features an access point.
The method according to claim 6,
Wherein the processor selects at least one of the BSS distinguisher or the device identifier,
Wherein the trigger signal is a signal for requesting a wireless communication terminal that senses a wireless signal including the selected BSS distinguisher or the selected device identifier to transmit the communication environment information.
The method of claim 3,
The communication environment information includes:
Wherein the information is information selected by the wireless communication terminal based on a time at which the wireless signal is received or intensity information of the wireless signal.
The method according to claim 1,
The processor identifies an external access point of another BSS that overlaps with the BSS of the access point by referring to the communication environment information,
The processor comprising:
The resource unit information, which is information on a resource unit used for transmission of a radio signal through a relay wireless communication terminal that transmits and receives a wireless signal with the access point and the external access point, Lt; / RTI >
Selects a resource unit of a frequency band different from a frequency band used by the external access point with reference to the resource unit information,
And the radio resource control unit transmits the data field of the radio signal to the radio communication terminal of the signal interference group which is a group including a radio communication terminal causing signal interference with the radio communication terminals in the other BSSs of the group An access point with.
10. The method of claim 9,
The processor comprising:
Using the transceiver unit, through the relay wireless communication terminal
The preamble configuration information of the wireless signal, and the wireless signal transmission timing information of the access point and the external access point from the external access point.
11. The method of claim 10,
The processor comprising:
Generates the same preamble as the external access point with reference to the preamble configuration information,
And transmits the same preamble in synchronization with transmission of a radio signal of the external access point when transmitting a radio signal through the transceiver.
11. The method of claim 10,
The processor comprising:
Wherein when the wireless signal is transmitted through the transceiver, the preamble and the data field of the wireless signal are separated, and the data field is discontinuously transmitted in the time domain after completion of the preamble transmission.
13. The method of claim 12,
Wherein the radio signal transmission timing information includes preamble transmission timing information and data field transmission timing information of the access point and the external access point,
The processor comprising:
When transmitting a radio signal through the transceiver,
Transmitting the separated preamble at the preamble transmission timing different from the preamble transmission timing of the external access point,
And transmits the separated data field at the same data field transmission timing as the data field transmission timing of the external access point.
In a wireless communication terminal,
A transmitting and receiving unit for transmitting and receiving a radio signal; And
And a processor for controlling the operation of the transceiver,
The processor comprising:
Receiving a radio signal transmitted from the external radio communication apparatus through the transceiving unit,
Extracting communication environment information indicating a communication environment from the radio signal,
And transmits the communication environment information to an access point included in the same BSS (Basic Service Set) as the wireless communication terminal through the transceiver,
When receiving a radio signal from the access point through the transceiver, the access point receives a radio signal transmitted based on the group,
Wherein the group comprises:
Wherein the access point identifies a distance between each wireless communication terminal in the BSS based on the communication environment information and classifies each wireless communication terminal in the BSS based on the determined distance. Terminal.
15. The method of claim 14,
The processor comprising:
When receiving a signal from a wireless communication device of another BSS overlapped with the BSS when receiving a wireless signal from the access point,
And transmits a signal requesting sharing of wireless communication related information to the access point and an external access point included in the other BSS through the transceiving unit, Transmitting resource unit information, which is information on a resource unit, to the access point,
And receives a data field of a radio signal transmitted from the access point using a resource unit of a frequency band different from a frequency band used by the external access point.
A method for controlling an access point,
Receiving communication environment information indicating a communication environment from at least one wireless communication terminal;
Determining a distance between each wireless communication terminal and another wireless communication terminal based on the received communication environment information;
Classifying the wireless communication terminals into at least one group based on the determined distances; And
And performing transmission of the wireless signal based on the group.
17. The method of claim 16,
Identifying an external access point of another BSS that overlaps with the BSS of the access point by referring to the communication environment information;
And resource unit information, which is information on a resource unit used for transmission of a radio signal with the external access point through a relay wireless communication terminal that transmits and receives a radio signal with the access point and the external access point, Receiving; And
Further comprising the step of selecting a resource unit of a band different from a frequency band used by the external access point with reference to the resource unit information,
Wherein the step of transmitting the radio signal comprises:
When transmitting a data field of a radio signal to a wireless communication terminal of a signal interference group which is a group including a wireless communication terminal causing signal interference with a wireless communication terminal in the BSS of the external access point, Wherein the access point is a mobile station.
A method of controlling a wireless communication terminal,
Receiving a wireless signal transmitted from an external wireless communication device;
Extracting communication environment information indicating a communication environment from the wireless signal;
Transmitting the communication environment information to an access point included in the same BSS (Basic Service Set) as the wireless communication terminal; And
When receiving a wireless signal from the access point, receiving the wireless signal transmitted by the access point based on the group,
Wherein the group comprises:
Wherein the access point identifies a distance between each of the wireless communication terminals in the BSS based on the communication environment information and classifies the wireless communication terminals in the BSS based on the determined distance. / RTI >
19. The method of claim 18,
Receiving a signal from a wireless communication terminal of another BSS overlapping with the BSS when receiving a wireless signal from the access point;
Transmitting a signal requesting sharing of wireless communication related information to the access point and an external access point included in the other BSS; And
Further comprising the step of transmitting, to the access point, resource unit information which is information on a resource unit received from the external access point,
The step of receiving the radio signal comprises:
And receiving a data field of a radio signal transmitted from the access point using a resource unit of a frequency band different from a frequency band used by the external access point.

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