KR101079656B1 - Method for Wireless Communications between Airborne Communication Nodes and Ground Terminals - Google Patents

Abstract

(a) obtaining a location of a plurality of terrestrial terminals for wireless communication with a plurality of public communication stations; and (b) each of the public communication stations is part of the plurality of terrestrial terminals based on the locations of the plurality of terrestrial terminals. Or determining a location of each of the public telecommunication stations to cover all of the plurality of public telecommunication stations and a plurality of terrestrial terminals. According to this method, in a wireless communication network including a plurality of terminals located on the ground, the communication yield can be increased by arranging a plurality of mobile communication stations in the air according to the communication speed, power consumption, and communication quality required by the terminals. have.

Public stations, terrestrial terminals, virtual MIMO

Description

Method for wireless communication between public communication station and ground terminal {Method for Wireless Communications between Airborne Communication Nodes and Ground Terminals}

The present invention relates to wireless communication, and more particularly, to perform a wireless communication by arranging a plurality of mobile communication nodes in the air to support the communication performance required by a plurality of terminals located on the ground. It's about technology.

In a communication network, there is a network having a hierarchical structure in which a communication station connected to a plurality of terminals and managing communication for the terminals exists above the terminals.

For example, when a data communication device such as a personal computer (PC), a laptop, a personal digital assistance (PDA), or the like communicates with each other, a relay or a router may include a plurality of relays or routers. Communication between data communication devices can be relayed. Specifically, the repeater receives data from one data communication device and transmits it to another data communication device, and the router sets and transmits a path for transmitting data to a destination in addition to the function of the repeater. When such a repeater or router is implemented in a wireless communication network, it has a predetermined coverage area.

On the other hand, in a wireless communication network such as a cellular network (cellular network), the base station has a function of relaying the communication to the terminal located within its communication area.

As described above, the communication station relays communication of the terminal, thereby providing communication performance such as communication rate and signal strength required by the terminal. In particular, in the wireless communication network, as the communication distance increases, the signal strength and the communication speed decrease rapidly, and thus, sufficient communication performance can be provided for a plurality of terminals by arranging the communication stations in close proximity to the terminals. In other words, in the wireless communication network, in order to support the communication yield required by a plurality of terminals, it is possible to appropriately set the position of a communication station having a predetermined communication enabled area.

The communication station may be fixed at a specific location, but may also be moved depending on the field of use of the wireless communication network. For example, when various obstacles exist on the ground, such as mountainous terrain, to provide communication to the terminal in an area where communication area is limited, or when the communication station itself moves, such as in military applications, the communication to the terminal is performed. When it is necessary to provide, instead of fixedly installing the communication station, it is possible to provide communication of the quality required by the terminal by controlling the position of the movable communication station.

Here, the mobile communication station can operate in the air. The altitude of a communication station has a great influence on the communication area of the communication station, and thus also affects the maximum transmit power required to maintain a constant communication area. In addition, the degree of communication failure caused by an obstacle also varies according to the altitude of the communication station.

Therefore, when the mobile communication station is to be located in the air to support the communication of a plurality of terminals located on the ground, how to arrange the mobile communication station in the air and accordingly, the communication station and the terminal according to what method or procedure You need to decide whether to do it.

SUMMARY OF THE INVENTION The present invention has been made aware of the above problems, and in the wireless communication network in which a plurality of terminals are located on the ground, a plurality of mobile communication stations are arranged in the air, thereby relaying communication to the plurality of terminals, thereby efficiently controlling the plurality of terminals located on the ground. The goal is to provide a way to support the situation.

The object of the present invention is not limited to the above-mentioned object, and other objects that are not mentioned will be clearly understood by those skilled in the art from the following description.

According to an embodiment of the present invention for achieving the above object, (a) obtaining a location of a plurality of terrestrial terminals to perform wireless communication with a plurality of public communication stations, and (b) the plurality of terrestrial terminals Determining a location of each of the public communication stations such that each of the public communication stations covers some or all of the plurality of terrestrial terminals based on a location of the plurality of public communication stations. do.

In addition, after step (c), after the step (b), the public communication station group including two or more public communication stations among the plurality of public communication stations covers the ground terminal group including two or more ground terminals among the plurality of ground terminals in common. In the case of providing a wireless communication method between a plurality of public communication stations and a plurality of terrestrial terminal comprising the step of performing communication between the group of the public communication station and the terrestrial terminal by a virtual multiple input multiple output (MIMO).

In addition, the step (a) is a step of each of the public communication stations receiving the first location information on the location of the plurality of terrestrial terminals from the upper base station, and each of the public communication stations are determined based on the first location information Generating location information with some or all of the plurality of terrestrial terminals by moving to a location; and sharing the connection information generated by each of the public communication stations with each other and updating the first location information; It provides a wireless communication method between a plurality of public communication stations and a plurality of terrestrial terminal comprising the step of obtaining the position of the plurality of terrestrial terminal from.

In the generating of the association information, each of the public communication stations moves to a position determined based on the first location information, and transmits its own public communication station identifier, and a ground terminal recognizing the public communication station identifier. Receiving, by each of the public communication stations, the terrestrial terminal identifier and the terrestrial terminal position information about its own location, wherein each of the public communication stations receives a service list using the terrestrial terminal identifier and the terrestrial terminal position information. And generating, wherein the linkage information provides a wireless communication method between a plurality of public communication stations and a plurality of terrestrial terminals including the service list.

In addition, the public communication station identifier provides a wireless communication method between a plurality of public communication stations and a plurality of terrestrial terminals that the public communication station repeatedly transmits while raising the altitude for a preset time.

In addition, the step (b) is a step of determining the distribution of the plurality of terrestrial terminals to either high density or low density based on the position of the plurality of terrestrial terminals, and if the distribution is determined to be high density At least one cell configured to cover some or all of the plurality of terrestrial terminals is configured such that two or more public communication stations among the plurality of terrestrial communication stations commonly cover two or more terrestrial terminals among the plurality of terrestrial terminals. If the position of each of the public communication stations is determined to exist abnormally, and if the distribution is determined to be low density, each of the public communication stations forms a cell so as to cover some or all of the plurality of terrestrial terminals, but the communication area of each of the public communication stations is established. Determine the location of each of the public communication stations so that they do not overlap with each other Provides a plurality of air stations and a plurality of wireless communication methods between the ground terminal including the steps:

The determining may include calculating a minimum value of the number of public communication stations required to cover all of the plurality of terrestrial terminals based on the positions of the plurality of terrestrial terminals, wherein the minimum value is the total number of the plurality of public communication stations. Determining the distribution at a higher density if smaller, and determining the distribution at a lower density if the minimum value is greater than or equal to the total number of the plurality of public communication stations. to provide.

에 의하여 산출하되, N_MS는 상기 복수의 지상 단말의 총수이고, D_MS는 단위 면적 당 상기 복수의 지상 단말의 개수이며, R은 상기 공중 통신국 각각의 최대 통신 가능 영역의 반지름이고, 함수

는 x를 넘는 최소 정수를 나타내는 복수의 공중 통신국과 복수의 지상 단말 간의 무선 통신 방법을 제공한다.In addition, the minimum value is

Where N _MS is the total number of the plurality of terrestrial terminals, D _MS is the number of the plurality of terrestrial terminals per unit area, R is the radius of the maximum reachable area of each of the public telecommunication stations,

Provides a method of wireless communication between a plurality of public communication stations and a plurality of terrestrial terminals representing a minimum integer greater than x.

In addition, the step (c) comprises the steps of generating a channel matrix between the group of public communication stations and the terrestrial terminal group, and setting a precoding matrix and a postcoding matrix using the channel matrix. And a wireless communication method between a plurality of terrestrial terminals.

In addition, the precoding matrix and the postcoding matrix provide a wireless communication method between a plurality of public communication stations and a plurality of terrestrial terminals configured by using a result of singular value decomposition of the channel matrix.

The step (c) may include generating a channel matrix between the group of public communication stations and the terrestrial terminal group, and setting a precoding matrix as an inverse of the channel matrix when an inverse of the channel matrix exists. Provided is a wireless communication method between a plurality of public communication stations and a plurality of terrestrial terminals.

In addition, in the step (c), a communication method between the plurality of public communication stations and the plurality of terrestrial terminals is provided such that the communication between the group of public communication stations and the terrestrial terminal group is performed by a virtual multiple input single output (MISO).

In addition, in step (c), a communication method between the plurality of public communication stations and the plurality of terrestrial terminals is provided so that the communication between the group of public communication stations and the terrestrial terminal group is performed by a virtual single input multiple output (SIMO).

Specific details according to still another embodiment of the present invention are included in the following description and drawings.

According to an embodiment of the present invention, in a wireless communication network including a plurality of terminals located on the ground, the communication yield can be increased by arranging a plurality of mobile communication stations in the air according to the communication speed, power consumption, and communication quality required by the terminals. It has an effect.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms, and the embodiments merely provide a complete description of the present invention and those skilled in the art to which the present invention pertains. It is provided to fully inform the scope of the invention, and the invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout. In addition, when it is determined that the detailed description of the related well-known configuration or function may obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Throughout the specification, including the claims, the term "communication station" is used to refer to an apparatus having a predetermined communication area and providing communication to a terminal within the communication area, and refers to a relay, a router, a base station, or the like of a communication network. It is a concept that includes but is not limited to all.

Hereinafter, with reference to the accompanying drawings will be described embodiments of the present invention;

1A and 1B are diagrams schematically illustrating a configuration of a wireless communication network according to an embodiment of the present invention.

As shown in FIGS. 1A and 1B, the wireless communication network 100 is a plurality of public communication stations 120, 122, 124 arranged in the air as mobile communication stations capable of operating in the air and a plurality of ground stations. Ground terminals 140, 142, 144, 145, 146, 147. Here, the public communication stations (120, 122, 124) may be installed or mounted in a helicopter, a plane or an unmanned aerial vehicle (UAV), the ground terminal (140, 142, 144, 145, 146, 147) is a vehicle It may be a terminal installed or mounted on the mobile equipment or may be a portable terminal.

In addition, as shown in FIGS. 1A and 1B, the wireless communication network 100 transmits data to and from the terrestrial terminals 140, 142, 144, 145, 146, 147 through the relay of the public communication stations 120, 122, 124. It may include one or more upper base station 160 that can transmit and receive. On the other hand, when the distance between the upper base station 160 and the public communication stations 120, 122, 124 is far away, another public communication station (not shown) to perform a relay function between the upper base station 160 and the public communication stations (120, 122, 124) One or more h) may be arranged to form a relay network.

1A and 1B, a public communication station 120, 122, 124 may communicate with terrestrial terminals 140, 142, 144, 145, 146, 147 located within its communicable area. In addition, the public communication stations 120, 122, 124 can communicate with each other, and the ground terminals 140, 142, 144, 145, 146, 147 can also communicate with each other. Here, a radio interface used for communication between the public communication stations 120, 122, 124 and the terrestrial terminals 140, 142, 144, 145, 146, 147, between the public communication stations 120, 122, 124 A wireless interface used for mutual communication and a wireless interface used for mutual communication between the terrestrial terminals 140, 142, 144, 145, 146, and 147 may be distinguished from each other. That is, the public communication stations 120, 122, 124 may have two air interfaces, and similarly, the terrestrial terminals 140, 142, 144, 145, 146, 147 may have two air interfaces.

1A and 1B, generally, a public wireless communication network may have a line-of-sight (LOS) between public communication stations 120, 122, and 124. , The burden of exchanging signals between 124 is small, and thus cooperative communication between public communication stations 120, 122, and 124 may be considered. As shown in FIGS. 1A and 1B, among the public telecommunication stations 120, 122, 124, the cooperative communication between the public telecommunication stations 120, 122, 124 in a public wireless communication network constituted by the public telecommunication stations 120, 122, 124. There may be a header public telecommunications station 120 that controls this.

Meanwhile, referring to FIGS. 1A and 1B, when the communication yield of the terrestrial wireless communication network including the terrestrial terminals 140, 142, 144, 145, 146, and 147 is high, the terrestrial terminals 140, 142, 144, 145, Cooperative communication between 146 and 147 may also be considered. As shown in FIGS. 1A and 1B, among terrestrial terminals 140, 142, 144, 145, 146, 147, cooperative communication between terrestrial terminals 140, 142, 144, 145, 146, 147 within a terrestrial wireless communication network. There may be a header terrestrial terminal 140 to control.

Further, referring to FIGS. 1A and 1B, the upper base station 160 is a public communication station identifier capable of identifying the public communication stations 120, 122, and 124 with each other and the terrestrial terminals 140, 142, 144, 145, 146, 147. ) Transmits the terrestrial terminal identifier of the terrestrial terminal to be connected to the public communication station (120, 122, 124) and receives whether the terrestrial terminal is to be connected from the public communication station (120, 122, 124) to establish a wireless communication link. Can be formed. Here, referring to FIG. 1A, a wireless communication link between an upper base station 160 and terrestrial terminals 140, 142, 144, 145, 146, 147 is directly controlled by an upper base station 160. And other public communication stations 122 and 124 controlled by the upper base station 160 through such a public communication station 120. Alternatively, referring to FIG. 1B, each of the public communication stations 120, 122, 124 performing relaying between the upper base station 160 and the terrestrial terminals 140, 142, 144, 145, 146, and 147 may be the upper base station 160. It can also be controlled directly by

As shown in FIGS. 1A and 1B, in accordance with an embodiment of the present invention, the public telecommunications stations 120, 122, 124 may each partially or entirely provide the terrestrial terminals 140, 142, 144, 145, 146, 147. It is arranged to cover. Here, the positions of the public communication stations (120, 122, 124) is determined based on after obtaining the positions of the plurality of terrestrial terminals (140, 142, 144, 145, 146, 147).

Here, according to the embodiment of the present invention, the positions of the plurality of terrestrial terminals 140, 142, 144, 145, 146, 147 may be obtained as follows.

First, each of the public communication stations 120, 122, 124 is a plurality of terrestrial terminals 140, 142, 144, 145, 146, 147 to obtain the position of the plurality of terrestrial terminals 140, 142, 144, 145, 146. , 147, obtains rough information regarding the position. For example, each of the public communication stations 120, 122, and 124 may receive first location information, which is rough information about the location of the terrestrial terminals 140, 142, 144, 145, 146, and 147, from the upper base station 160. have.

Next, each of the public communication stations 120, 122, and 124 moves to an appropriate location based on the first location information. For example, each of the public telecommunication stations 120, 122, 124 is determined based on the first location information to obtain accurate information about the location of some or all of the terrestrial terminals 140, 142, 144, 145, 146, 147. Can be moved to a location. Each of the mobile communication stations 120, 122, and 124 thus moved generates connection information with some or all of the terrestrial terminals 140, 142, 144, 145, 146, and 147 to obtain accurate location information.

In this case, the linkage information between each of the public communication stations 120, 122, and 124 and some or all of the terrestrial terminals 140, 142, 144, 145, 146, and 147 may be specifically generated as follows.

Each of the public communication stations 120, 122, and 124 moves to a position determined based on the first positional information and turns in the air, and transmits its public communication station identifier using a beam having a directivity to the ground. The public communication station identifier transmitted by each of the public communication stations 120, 122, and 124 may be repeated or periodically in a predetermined band between the public communication stations 120, 122, and 124 and the terrestrial terminals 140, 142, 144, 145, 146, and 147. Can be sent out. In this case, for example, a reliable modulation and coding scheme (MCS) level may be used so that the terrestrial terminal 140, 142, 144, 145, 146, 147 can easily decode the public terminal identifier.

The terrestrial terminals 140, 142, 144, 145, 146, and 147 recognize the public communication station identifiers transmitted by the public communication stations 120, 122, and 124, and the terrestrial terminal position, which is information about its terrestrial terminal identifier and its location. Send the information. Here, the terrestrial terminal location information may be in the form of GPS information.

Meanwhile, a plurality of terrestrial terminals 140, 142, 144, 145, 146, and 147 transmit terrestrial terminal identifiers and terrestrial terminal location information to the public communication stations 120, 122, and 124. 124 may mitigate a collision between terrestrial terminals 140, 142, 144, 145, 146, 147 transmitting terrestrial terminal identifiers by repeatedly transmitting the public communication station identifier while gradually raising the altitude for a preset time. . Alternatively, the terrestrial terminals 140, 142, 144, 145, 146, and 147 transmit the terrestrial terminal identifiers by using orthogonal codes, thereby terminating the terrestrial terminals 140, 142, 144, 145, 146, and 147. The collision between them can be prevented.

After the public terminal 120, 122, 124 receives the terrestrial terminal identifier and the terrestrial terminal location information transmitted by the terrestrial terminals 140, 142, 144, 145, 146, and 147, which have recognized the public terminal identifier, A service list is generated using the ground terminal identifier and the ground terminal location information.

Thereafter, each of the public communication stations 120, 122, and 124 shares the linkage information including the service list generated by the public communication stations 120 to update the first location information. For example, a map capable of knowing the distribution of the terrestrial terminals 140, 142, 144, 145, 146, 147 can be created by sharing mutual information generated by each of the public communication stations 120, 122, 124. In this way, each of the public communication stations 120, 122, 124 is updated from the second location information containing the more accurate location information by updating the first location information, and the plurality of terrestrial terminals 140, 142, 144, 145, 146, 147. To obtain the position of. Here, each of the public communication stations 120, 122, and 124 is based on the positions of the plurality of terrestrial terminals 140, 142, 144, 145, 146, and 147 thus obtained. According to the distribution of the 145, 146, and 147 or the hierarchical organization among the plurality of terrestrial terminals 140, 142, 144, 145, 146, and 147, their positions may be determined and arranged according to the determined positions.

2A and 2B are diagrams illustrating a result of disposing a public communication station according to a distribution of terrestrial terminals in a wireless communication network according to an exemplary embodiment of the present invention.

2A and 2B, the distribution of the terrestrial terminal may vary according to circumstances. For example, it may be classified into a case where a relatively large number of terrestrial terminals are concentrated in a narrow area and have a high density distribution, and a case where a relatively small number of terrestrial terminals are spread in a large area and having a low density distribution.

As shown in FIG. 2A and FIG. 2B, considering when the plurality of public communication stations 200 and 202 are available, the plurality of terrestrial terminals are distributed in a high density based on the positions of the plurality of terrestrial terminals. After determining whether the system has a low density or a low density distribution, the public communication stations 200 and 202 may be arranged as follows.

First, referring to FIG. 2A, when the distribution of a plurality of terrestrial terminals is determined to be high density, all of the plurality of terrestrial terminals are present in the communicable area 240a of one public communication station 200. The communication station 200 may sufficiently cover all of the plurality of terrestrial terminals constituting the terrestrial wireless communication network. However, since a single public communication station 200 covers a plurality of terrestrial terminals, a communication speed between the public communication station 200 and the plurality of terrestrial terminals may be lowered. Therefore, by determining and arranging the positions of the public communication stations 200 and 202 so that the communicable area 240a of one public communication station 200 and the communicable area 242a of the other public communication station 202 overlap each other. Yield can be increased.

Next, referring to FIG. 2B, when the distribution of the plurality of terrestrial terminals is determined to be low density, the communicable area 240b of one public communication station 200 does not cover all of the plurality of terrestrial terminals. Therefore, each of the public communication stations 200 and 202 forms a cell corresponding to each of the public communication stations 200 and 202 so as to cover some of the plurality of terrestrial terminals, but forms each cell independently. That is, the positions of the public communication stations 200 and 202 are determined and arranged so that the communication areas 240b and 242b of the public communication stations 200 and 202 forming each cell are not overlapped with each other to cover all the plurality of terrestrial terminals. Can be. For example, referring to FIG. 2B, the public communication stations 200 and 202 may be located at the same altitude, but the public communication stations may cover all of the plurality of terrestrial terminals in the communication areas 240 and 242 of the public communication stations 200 and 202. (200, 202) can be arranged as dispersed as possible.

Furthermore, according to an embodiment of the present invention, when a plurality of terrestrial communication stations perform wireless communication with a plurality of terrestrial terminals, when the distribution of the plurality of terrestrial terminals is determined to be high density, even a part of the public communication stations may communicate. It is possible to cover all of the plurality of terrestrial terminals sufficiently, and the redundant public communication stations can be further arranged to cover the terrestrial terminals requiring high communication quality. Accordingly, when the distribution of the plurality of terrestrial terminals is determined to be high density, it is possible for two or more public communication stations among the plurality of terrestrial communication stations to cover two or more terrestrial terminals among the plurality of terrestrial terminals in common. In other respects, when the distribution of the plurality of terrestrial terminals is determined to be high density, two or more of the plurality of public communications stations are among the cells formed such that each of the plurality of public communications stations covers some or all of the plurality of terrestrial terminals. The location of each of the public communication stations may be determined such that there is at least one cell formed so that the communication station commonly covers two or more ground terminals among the plurality of ground terminals. In such a case, when the cell is formed to cover the terrestrial terminal by determining and arranging the position of the public communication station, the cell may be formed so that two or more public communication stations commonly cover the terrestrial terminal requiring high communication quality. Can be.

On the other hand, according to an embodiment of the present invention, when the distribution of the plurality of terrestrial terminals is determined to be low density, it is possible to cover all of the plurality of terrestrial terminals by distributing them so that communication areas of the plurality of public communication stations do not overlap each other. Can be. Here, by adjusting the altitude of each of the plurality of public communication stations in accordance with the communication performance required by each of the plurality of terrestrial terminals to change the communication possible area, it is possible to adjust the size of the cell formed by each of the public communication stations.

More specifically, according to an embodiment of the present invention, if the position of the plurality of terrestrial terminals can be determined whether the distribution of the plurality of terrestrial terminals is high density or low density, for example, the positions of the plurality of terrestrial terminals obtained The distribution of the plurality of terrestrial terminals is determined in a high density by comparing the minimum number of public communication stations necessary to cover all of the plurality of terrestrial terminals with the total number of public communication stations that will perform wireless communication with the plurality of terrestrial terminals based on Or low density. That is, after calculating the minimum value of the number of public communication stations required to cover all of the plurality of ground terminals based on the obtained positions of the plurality of terrestrial terminals, the minimum value is compared with the total number of the plurality of terrestrial communication stations. In this case, when a plurality of public communication stations larger than the minimum value perform wireless communication with the plurality of terrestrial terminals, some of the terrestrial terminals may cover all of the plurality of terrestrial terminals. According to the quality of service required can be additionally arranged, it can be determined that the plurality of terrestrial terminals are distributed in a high density. On the contrary, when the public communication station having the above minimum value performs wireless communication with the plurality of terrestrial terminals, it may be determined that the distribution of the plurality of terrestrial terminals is low density. In this case, the terrestrial terminals are scattered over a large area that cannot be fully covered by a given public telecommunication station alone, so that more public telecommunication stations may be needed to fully support a plurality of terrestrial terminals. The public telecommunications stations may be distributed and arranged to cover them.

Next, according to an embodiment of the present invention, when the number of terrestrial terminals is N _MS and the average density of the terrestrial terminals, that is, the number of terrestrial terminals per unit area is D _MS , a plurality of terrestrial terminals to perform wireless communication with the terrestrial terminals. The public telecommunication station may be located as follows.

(여기서,

는 x를 넘는 최소 정수를 말한다)에 의하여 산출할 수 있다.Firstly, the expected terrestrial wireless network is N _MS / D _MS . At this time, the maximum communicable area of the public communication station which can be arranged can be represented by πR ² , the area of a circle having a radius R, for example, depending on the maximum communication distance of the public communication station and the altitude from the ground. Therefore, the minimum value of the number of public telecommunication stations required to cover all the terrestrial terminals constituting the terrestrial wireless telecommunication network is

(here,

Is the minimum integer greater than x).

와 N_AIR를 비교함으로써 지상 단말의 분포가 고밀도인지 저밀도인지 구분할 수 있고, 그에 따라 공중 통신국의 위치를 결정할 수 있다.At this time, when the number of public communication stations to be arranged to cover the ground terminal is N _AIR ,

By comparing with N _AIR , it is possible to distinguish whether the distribution of the terrestrial terminal is high density or low density, thereby determining the location of the public communication station.

3 is a view showing a result of arranging a public communication station when the distribution of the terrestrial terminal in the wireless communication network according to an embodiment of the present invention is high density.

As shown in FIG. 3, when the plurality of terrestrial terminals 340, 341, 342, 343, 344, 345, 350, 351, 352, 353, 360 and 361 have a high density distribution, for example, the plurality of terrestrial terminals The number of public stations (300, 302, 304, 340, 341, 342, 343, 344, 345, 350, 351, 352, 353, 360, 361) is greater than the minimum of the number of public stations required to cover all of them. If 306 is deployable, each of the public communication stations 300, 302, 304, 306 is part of a terrestrial terminal 340, 341, 342, 343, 344, 345, 350, 351, 352, 353, 360, 361 or The cells may be formed to cover all of them, but the number of cells formed may be greater than or equal to the above minimum value and smaller than the total number of public communication stations 300, 302, 304, and 306.

Here, referring to FIG. 3, when the communication quality required by some terrestrial terminals 340, 341, 342, 343, 344, and 345 is particularly high, the two public communication stations 300 and 302 may use the above ground terminals 340,. 341, 342, 343, 344, 345 to cover common and other public communication stations 304, 306 to cover the ground terminal (350, 351, 352, 352) and ground terminal (360, 361), respectively. 300, 302, 304, 306 may be determined and placed respectively. In this case, the public telecommunications station group including two or more public communication stations 300 and 302 which commonly cover the ground terminal group including two or more ground terminals 340, 341, 342, 343, 344, and 345 is public. By arranging the communication areas overlapping each other at different altitudes of the communication stations 300 and 302, it is possible to provide the necessary communication performance as much as possible. Further, in order to increase the communication yield between the public telecommunications station group including two or more public communication stations (300, 302) and the terrestrial terminal group including two or more ground terminals (340, 341, 342, 343, 344, and 345). For example, a smart antenna to beam forming or network coding may be used. In particular, a multiple input multiple output (MIMO) technique may be used.

4 is a diagram illustrating a channel between a public communication station and a terrestrial terminal in a wireless communication network according to an embodiment of the present invention.

Referring to FIG. 4, while LOS communication is possible between the public communication station 400 and the ground terminal 420, a reflection signal by the ground and a reflection signal by the terrain around the ground terminal exist. A multipath fading phenomenon occurs between the public communication station 400 and the terrestrial terminal 420. As a result, the ground terminal 420 undergoes different multipath fading from other ground terminals (not shown). Thus, for the public communication station 400, the terrestrial terminal 420 has a channel independent of other terrestrial terminals (not shown). When additionally deploying another public communication station (not shown), the ground terminal 420 similarly has a communication channel independent of other land terminals (not shown) for the additionally deployed public communication station (not shown). .

In such a case, when a plurality of public communication stations including one or more antennas are arranged to support a terrestrial wireless communication network composed of a plurality of terrestrial terminals having one or more antennas, efficient communication may be applied by applying virtual MIMO technology. You can do that.

5 is a diagram illustrating a case in which communication is performed between a public telecommunication station group and a ground terminal group using virtual MIMO according to an embodiment of the present invention.

Referring to FIG. 5, when a plurality of terrestrial terminals 520 and 522 are distributed at a high density in a narrow area, the public terminals may communicate with each other through cooperative communication between public communication stations 500 and 502 and cooperative communication between terrestrial terminals 520 and 522. The communication yield can be improved by performing communication between the communication stations 500 and 502 and the terrestrial terminals 520 and 522 by virtual MIMO.

For example, as shown in FIG. 6, which illustrates the structure of a communication network for virtual MIMO according to an embodiment of the present invention, public communication including four public communication stations 600, 602, 604, and 606 capable of communicating with each other. In the case of performing wireless communication between the terrestrial terminal group including four terrestrial terminals 620, 622, 624, and 626 that can communicate with the ROK military, the operation of the virtual MIMO is as follows. Hereinafter, a case in which the public communication stations 600, 602, 604, and 606 each have one antenna, and the terrestrial terminals 620, 622, 624, and 626 also have one antenna will be described. It goes without saying that any combination of transmit and receive antennas with one or more terrestrial terminals having a plurality of antennas may be considered. In addition, the following description will be given by considering downlink in which a public communication station is a transmitting side and a terrestrial terminal is a receiving side. However, the wireless communication method and apparatus provided by the present invention also provide an uplink. Naturally, it can be applied.

Referring to FIG. 6, among the public communication stations 600, 602, 604, and 606, there is a header public communication station 600 that controls cooperative communication between the public communication stations 600, 602, 604, and 606. Among the 622, 624, and 626 is a header terrestrial terminal 620 that controls cooperative communication between terrestrial terminals 620, 622, 624, and 626. As mentioned above, there is an independent channel between each terrestrial terminal 620, 622, 624, 626 and each public telecommunication station 600, 602, 604, 606.

Referring to FIG. 6, when the channel coefficient between the i th public communication station and the j th ground terminal is h _ji , the public communication station group and the ground terminal 620 including the public communication stations 600, 602, 604, and 606 are referred to. A channel matrix H between terrestrial terminal groups including 622, 624, and 626 may be expressed by Equation 1 below.

Meanwhile, the channel vector h _i between the i-th public communication station and the terrestrial terminal may be described as in Equation 2 below.

Each public communication station 600, 602, 604, 606 may obtain a channel vector, for example the i th public communication station transmits a pilot signal to feed back from each terrestrial terminal 620, 622, 624, 626. By receiving, the channel vector h _i can be obtained, and through this process, the channel matrix H can be obtained. For example, referring to FIG. 6, the remaining public communication stations 602, 604, 606 except for the header public communication station 600 transmit the channel vectors thus collected to the header public communication station 600, and the header public communication station ( 600 may obtain the channel matrix H from the channel vectors h ₀ collected from the channel vectors h ₁ , h _2, and h ₃ received from other public communication stations 602, 604, and 606.

When the signal to be transmitted from the upper communication station 660 to the terrestrial terminals 620, 622, 624, and 626 arrives at the header public communication station 600, the header public communication station 600 is connected to the terrestrial terminals 620, 622, 624, and 626. Signal to be transmitted to all public communication stations 602, 604, and 606 except for the header public communication station 600. Here, when s _i denotes data to be transmitted to the terrestrial terminals 620, 622, 624, and 626 by the i-th public communication station, a signal s to be transmitted to the terrestrial terminals 620, 622, 624, and 626 is expressed by the following equation. It can be described as 3.

The signal s to be transmitted to the terrestrial terminals 620, 622, 624, and 626 is transmitted to the terrestrial terminals 620, 622, 624, via a communication channel represented by the channel matrix H by the relay of the public communication stations 600, 602, 604, and 606. 626.

In this case, the public communication stations 600, 602, 604, and 606 may transmit signals to the terrestrial terminals 620, 622, 624, and 626 using a precoding technique. To this end, for example, the precoding matrix P _pre obtained by decomposing the channel matrix H by singular value decomposition (SVD) or a similar operation is transmitted to the terrestrial terminals 620, 622, 624, and 626. It can be transmitted to the terrestrial terminal 620, 622, 624, 626 through the communication channel represented by the channel matrix H by multiplying the signal to be transmitted s. If the channel between the public communication stations 600, 602, 604, 606 and the terrestrial terminals 620, 622, 624, 626 does not change for a certain time, the selected precoding matrix P _pre may continue to be used for data transmission during that time.

On the other hand, as mentioned above, when the header public communication station 600 obtains the channel matrix H, the header public communication station 600 obtains the precoding matrix P _pre by decomposing the channel matrix H by singular value decomposition or a similar operation. Can be. Further, the header public communication station 600 may transmit the obtained precoding matrix P _pre to all the public communication stations 602, 604, and 606 except for the header public communication station 600, and each public communication station 600, 602, 604 and 606 may multiply the precoding matrix P _pre by the signal s to be transmitted to the terrestrial terminals 620, 622, 624 and 626 to obtain a result as shown in Equation 4 below.

Each public communication station 600, 602, 604, 606 transmits a precoded signal simultaneously, e.g., the i th public communication station transmits x _i . On the other hand, when the signal transmitted by the public communication station (600, 602, 604, 606) passes through the communication channel represented by the channel matrix H is n, the noise applied when the j-th ground terminal receives the signal If n _j , n can be described as in Equation 5 below.

In this case, when the signal received by the j th transmission terminal is y _i , the signal y received by the terrestrial terminals 620, 622, 624, and 626 may be expressed by Equation 6 below.

At this time, the signal s transmitted by the public communication stations 600, 602, 604, and 606 to the terrestrial terminals 620, 622, 624, and 626 is estimated from the signal y received by the terrestrial terminals 620, 622, 624, and 626. can do. For example, when the header public communication station 600 obtains the channel matrix H and performs singular value decomposition on the channel matrix H as shown in Equation 7 below, the signal s may be estimated as follows.

Where S is a singular value matrix of H. In this case, each public communication station 600, 602, 604, 606 transmits the precoded signal with the precoding matrix set to P _pre = V. Each terrestrial terminal 620, 622, 624, 626 receives a signal transmitted by the public communication stations 600, 602, 604, 606, and the other terrestrial terminals 622, 624, 626 except for the header terrestrial terminal 620 ) Transmits the received signal to the header terrestrial terminal 620. The header terrestrial terminal 620 may obtain y from the signals y ₀ received by the terminal and the signals y ₁ , y _2, and y ₃ received from the other terrestrial terminals 622, 624, and 626. The header terrestrial terminal 620 sets the postcoding matrix to P _post = U ^H based on the matrix U obtained from Equation 7 above, and then is received by the terrestrial terminals 620, 622, 624, and 626. By multiplying one signal y by the postcoding matrix P _post , an estimate of the signal s transmitted by the public communication stations 600, 602, 604, and 606 to the terrestrial terminals 620, 622, 624, and 626 can be obtained. At this time, the post-coding matrix P _post may be obtained by the header terrestrial terminal 620 received from the header public communication station 600, or may be obtained by collecting the channel matrix H from the terrestrial terminals 620, 622, 624, and 626. It may be.

According to another example, when there is an inverse matrix H ⁻¹ of the channel matrix H obtained by the header public communication station 600, each public communication station 600, 602, 604, and 606 converts the precoding matrix to P _pre = H ^{−. Set to 1} and transmit the precoded signal. Each terrestrial terminal (620, 622, 624, 626) receives a signal transmitted by the public communication stations (600, 602, 604, 606), with the equation (6) is y = s + n, S ₀ , s ₁ , s _2, and s ₃ may be estimated directly from the signals y ₀ , y ₁ , y _2, and y ₃ received by each terrestrial terminal 620, 622, 624, 626. For example, when cooperative communication between terrestrial terminals 620, 622, 624, and 626 is impossible, each public communication station 600, 602, 604, and 606 sets the precoding matrix to P _pre = H ^-1 as described above. A technique of transmitting the precoded signal may be used.

On the other hand, even when a plurality of terrestrial terminals are concentrated in the mutually communicable area as shown in FIG. 5, cooperative communication between the ground terminals may be difficult or cooperative communication between public communication stations may be difficult. In such a case, a signal is transmitted from a plurality of public communication stations to each terrestrial terminal by using a virtual multiple input single output (MISO), which is a subset of the operation method of virtual MIMO, or A signal may be transmitted from each public telecommunication station to a plurality of terrestrial terminals using a virtual single input multiple output (SIMO).

7 is a diagram illustrating a case where communication is performed using a ground terminal and a virtual MISO through cooperative communication between a plurality of public communication stations according to an embodiment of the present invention.

Referring to FIG. 7, if a plurality of terrestrial terminals are distributed in a relatively narrow area, but cooperative communication between a plurality of terrestrial terminals is difficult, while cooperative communication between a plurality of public communication stations 700 and 702 is possible, a virtual MISO technique may be used. Through this, communication yield can be increased. Since the cooperative communication is not performed between the plurality of terrestrial terminals, orthogonal communication resources that do not interfere with each other may be used. For example, a plurality of public telecommunication stations 700 and 702 may use Time Division Multiple Access in a manner that supports one terrestrial terminal 720.

Meanwhile, in the case of using the virtual MISO method, the channel matrix H in Equation 1 may be replaced with a vector h of 1x4, which is a channel vector in the multiplexed antenna. In addition, since the matrix U becomes 1 as a scalar value in Equation 7, it is not necessary to separately perform a postcoding process on the ground terminals 620, 622, 624, and 626.

8 is a diagram illustrating a case where communication is performed using a public SIM and a virtual SIMO through cooperative communication between a plurality of terrestrial terminals according to an embodiment of the present invention.

Referring to FIG. 8, when a plurality of public communication stations are arranged in close proximity to each other but cooperative communication between a plurality of public communication stations is difficult, while cooperative communication between a plurality of terrestrial terminals 820 and 822 is possible, a virtual MISO technique may be used. Can be. In this case, a plurality of terrestrial terminals 820 and 822 receive signals transmitted by one public communication station 800 through independent channels, respectively, and obtain multiplexing gains through cooperation between terrestrial terminals 820 and 822. Can be.

Meanwhile, in the case of using the virtual SIMO method, the channel matrix H in Equation 1 may be replaced with a vector h of 4 × 1 which is a channel vector of the multiple reception antenna. In addition, since the matrix V becomes 1 as a scalar value in Equation 7, the precoding process on the side of the public communication stations 600, 602, 604, and 606 is unnecessary.

9 is a flowchart illustrating a process of wireless communication between a plurality of public communication stations and a plurality of terrestrial terminals according to an embodiment of the present invention.

Referring to FIG. 9, first, locations of a plurality of terrestrial terminals are obtained (S900).

으로 결정할 수 있다.Next, the minimum value of the number of public communication stations required to cover all of the plurality of terrestrial terminals is calculated based on the obtained positions of the plurality of terrestrial terminals (S910). For example, when the number of terrestrial terminals constituting the terrestrial wireless communication network is N _MS , the number of terrestrial terminals per unit area is D _MS, and the maximum communication area of the deployable public communication station is πR ² , the area of a circle having a radius R. The minimum value is

Can be determined.

Next, the minimum value calculated previously is compared with the total number of public communication stations which can be arranged (S920). As a result, the distribution of terrestrial terminals is low enough that the terrestrial terminals are distributed at a high density enough to cover the plurality of terrestrial terminals with a plurality of public communication stations that can be arranged, or that the plurality of public communication stations need to be distributed and arranged as much as possible. Awareness can be distinguished and, accordingly, the location of the public telecommunications station can be determined.

If the total number of public communication stations that can be deployed is larger than the minimum value above, the deployable public communication stations can cover all of the plurality of terrestrial terminals sufficiently, and the cells are formed so that each of the public communication stations covers some or all of the plurality of terrestrial terminals. However, in at least one of the cells thus formed, the location of each of the public communication stations is determined so that the public communication station group including two or more public communication stations covers the ground terminal group including two or more ground terminals in common (S930). For example, it is possible to cover all of the plurality of terrestrial terminals by forming as many cells as the minimum value or the number larger than the minimum value and smaller than the total number of deployable public communication stations and arranging at least one public communication station for each cell. In such a case, by arranging a plurality of public communication stations in preference to cells in which the ground terminals having high required communication quality are located, it is possible to cover all of the plurality of ground terminals while providing maximum required communication performance.

If a public telecommunication station group including two or more public telecommunication stations commonly covers a ground terminal group including two or more ground terminals, a channel may be used for communication between the public telecommunication station group and the ground terminal group using virtual MIMO. A matrix is set (S940). In particular, when cooperative communication is possible between the public communication stations included in the public communication station group and the cooperative communication is possible between the ground terminals included in the ground terminal group, communication performance using virtual MIMO can provide the necessary communication performance to the maximum. have. On the other hand, when cooperative communication between the terrestrial terminals included in the terrestrial terminal group is difficult, the virtual MISO can be used, and when the cooperative communication between the public communication stations included in the public communication station group is difficult, a virtual SIMO can be used.

If the above minimum value is larger than the total number of deployable public communication stations, the terrestrial terminals are distributed in a large area that cannot be sufficiently supported by the deployable public communication stations alone. (S950). If it is necessary to widen the coverage area of the public communication station in order to cover the entire area of the terrestrial wireless communication network, for example, it is possible to lower the altitude of the public communication station or increase the strength of the signal transmitted from the public communication station.

Thereafter, wireless communication is performed between the plurality of public communication stations and the plurality of terrestrial terminals (S960).

Embodiments of the present invention may be implemented in the form of program instructions that can be executed by various computer means and recorded in a computer-readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic-optical media such as floppy disks. This includes hardware devices specifically configured to store and execute program instructions such as magneto-optical media and ROM, RAM, and flash memory. The medium may be a transmission medium such as an optical or metal line, a wave guide, or the like, including a carrier wave for transmitting a signal designating a program command, a data structure, or the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may be embodied in other specific forms without changing the technical spirit or essential features of the present invention. I can understand that. Therefore, the embodiments described above are illustrative in all respects and should not be understood as limiting.

1A and 1B are diagrams schematically illustrating a configuration of a wireless communication system according to an embodiment of the present invention.

2A and 2B illustrate a result of disposing a public communication station according to a distribution of terrestrial terminals in a wireless communication system according to an exemplary embodiment of the present invention.

3 is a view showing a result of arranging a public communication station when the distribution of the terrestrial terminal in the wireless communication system according to an embodiment of the present invention is high density.

4 is a diagram illustrating a channel between a public communication station and a terrestrial terminal in a wireless communication system according to an embodiment of the present invention.

5 is a diagram illustrating a case of performing communication using virtual MIMO between a plurality of public communication stations and a plurality of terrestrial terminals according to an embodiment of the present invention.

6 is a diagram illustrating a structure of a communication network for virtual MIMO according to an embodiment of the present invention.

7 is a diagram illustrating a case where communication is performed using a ground terminal and a virtual MISO through cooperative communication between a plurality of public communication stations according to an embodiment of the present invention.

8 is a diagram illustrating a case where communication is performed using a public SIM and a virtual SIMO through cooperative communication between a plurality of terrestrial terminals according to an embodiment of the present invention.

9 is a flowchart illustrating a process of wireless communication between a plurality of public communication stations and a plurality of terrestrial terminals according to an embodiment of the present invention.

Claims (13)

(a) obtaining a location of a plurality of terrestrial terminals for wireless communication with a plurality of public communication stations; (b) determining a location of each of the public communication stations so that each of the public communication stations covers some or all of the plurality of terrestrial terminals based on the locations of the plurality of terrestrial terminals, Step (a) is Receiving, by each of the public communication stations, first location information about the locations of the plurality of terrestrial terminals from an upper base station; Generating, by each of the public communication stations, a connection information with a part or all of the plurality of terrestrial terminals by moving to a location determined based on the first location information; Acquiring the positions of the plurality of terrestrial terminals from the second position information of each of the public communication stations by sharing the linkage information generated by the public communication stations with each other and updating the first position information. A wireless communication method between a plurality of public communication stations and a plurality of terrestrial terminals. The method of claim 1, (c) after step (b), a public communication station group including two or more public communication stations among the plurality of public communication stations commonly covers a ground terminal group including two or more ground terminals among the plurality of ground terminals. In the case of performing communication between the public telecommunication station group and the terrestrial terminal group by a virtual multiple input multiple output (MIMO). Wireless communication method between a plurality of public communication stations and a plurality of terrestrial terminal comprising a. delete The method according to claim 1 or 2, The linkage information generation step Transmitting each of the public communication stations to a location determined based on the first location information and transmitting its own public communication station identifier; Receiving, by each of the public communication stations, its own ground terminal identifier transmitted by the ground terminal recognizing the public communications station identifier and the ground terminal position information about its location; Generating, by each of the public communication stations, a service list using the ground terminal identifier and the ground terminal location information; The linkage information includes the service list. A wireless communication method between a plurality of public communication stations and a plurality of terrestrial terminals. The method of claim 4, wherein The public communication station identifier is repeatedly transmitted while the public communication station increases the altitude for a preset time. A wireless communication method between a plurality of public communication stations and a plurality of terrestrial terminals. The method according to claim 1 or 2, Step (b) is Determining the distribution of the plurality of terrestrial terminals as either high density or low density based on the positions of the plurality of terrestrial terminals; When the distribution is determined to be high density, two or more public communication stations of the plurality of terrestrial terminals are selected from two or more of the plurality of terrestrial terminals in a cell configured to cover each part or all of the plurality of terrestrial terminals. The location of each of the public communication stations is determined such that there is at least one cell formed to cover the terrestrial terminals in common, and when the distribution is determined to be low density, each of the public communication stations is configured to partially or all of the plurality of terrestrial terminals. Forming a cell to cover, but determining a location of each of the public communication stations such that the communicable areas of each of the public communication stations do not overlap one another; A wireless communication method between a plurality of public communication stations and a plurality of terrestrial terminals. The method of claim 6, The determination step is Calculating a minimum value of the number of public communication stations required to cover all of the plurality of terrestrial terminals based on the positions of the plurality of terrestrial terminals; Determining the distribution as high density when the minimum value is less than the total number of the plurality of public communication stations, and determining the distribution as low density when the minimum value is greater than or equal to the total number of the plurality of public communication stations. A wireless communication method between a plurality of public communication stations and a plurality of terrestrial terminals. The method of claim 7, wherein The minimum value is

Calculated by N _MS is the total number of the plurality of terrestrial terminals, D _MS is the number of the plurality of terrestrial terminals per unit area, R is the radius of the maximum coverage area of each of the public communication stations, function

Is the smallest integer greater than x A wireless communication method between a plurality of public communication stations and a plurality of terrestrial terminals. 3. The method of claim 2, Step (c) is Generating a channel matrix between the public telecommunication station group and the terrestrial terminal group; Setting up a precoding matrix and a postcoding matrix using the channel matrix; A wireless communication method between a plurality of public communication stations and a plurality of terrestrial terminals. The method of claim 9, The precoding matrix and the postcoding matrix are set using a result of singular value decomposition of the channel matrix. A wireless communication method between a plurality of public communication stations and a plurality of terrestrial terminals. 3. The method of claim 2, Step (c) is Generating a channel matrix between the public telecommunication station group and the terrestrial terminal group; Setting a precoding matrix to an inverse of the channel matrix when the inverse of the channel matrix exists A wireless communication method between a plurality of public communication stations and a plurality of terrestrial terminals. 3. The method of claim 2, In the step (c) The communication between the public telecommunication station group and the terrestrial terminal group is performed by virtual multiple input single output (MISO). A wireless communication method between a plurality of public communication stations and a plurality of terrestrial terminals. 3. The method of claim 2, In the step (c) The communication between the public communication station group and the terrestrial terminal group is performed by a virtual single input multiple output (SIMO). A wireless communication method between a plurality of public communication stations and a plurality of terrestrial terminals.

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