KR101415669B1 - Device for vehicle communication and method thereof - Google Patents

Abstract

The present invention relates to an apparatus for communicating with a vehicle and a communication method thereof, and more particularly to an adaptive beam-based beam-division multiple access scheme in a smart antenna-based communication system in which an infrastructure exists, And a method of allocating beam and beam power capable of increasing the capacity of a communication system by mitigating interference within cells affecting the communication system.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a vehicle communication device,

The present invention relates to a vehicle communication device and a communication method thereof. More specifically, an adaptive beam-based beam division multiple access scheme is used in a smart antenna-based communication system in which an infrastructure exists, and a beam formed toward a vehicle mitigates communication interference in a cell affecting another vehicle To a vehicle communication apparatus using a smart antenna that provides a method of allocating beam and beam power capable of increasing the capacity of a communication system and a communication method thereof.

With the rapid development of the automobile industry, the development of TELEMATICS technology, which is a vehicle wireless Internet service that combines automobile and wireless communication, has increased the demand for wireless vehicle communication.

The vehicle communication system consists of the infrastructure of the vehicle and the surrounding roads to provide real-time traffic information and vehicle communication applications for the safety of the vehicle and the driver and the improvement of the traffic flow. Here, the vehicle communication application may include a road safety application that provides information about a vehicle in an emergency, a traffic management application that provides information about the traffic flow, and a user infotainment application that provides entertainment information through an Internet connection And the like.

Generally, a vehicle communication system includes a V2I (Vehicle to Infrastructure) communication system provided through wireless communication between an infrastructure and a vehicle, and a V2V (Vehicle to Vehicle) communication system provided through wireless communication between vehicles.

In the case of the V2I communication system, it is difficult to allocate resources in consideration of the location and the moving speed of the vehicle by applying a method of providing information through radio communication using an omnidirectional antenna in the past, so that communication capacity and QoS are lowered And there is a problem that unnecessary resources are wasted in a space without a vehicle.

In order to solve this problem, an adaptive beam-based beam division multiple access (OFDM) scheme, which maximizes a capacity of a communication system by preventing an unnecessary waste of communication resources by forming an adaptive beam in consideration of a vehicle position and a moving speed, .

The beam division multiple access scheme is a space reuse scheme for forming an adaptive beam in a plurality of vehicles simultaneously in the same frequency band, and is advantageous in that a large amount of data can be transmitted. However, as the spread of smart devices has increased in recent years, demand for user information applications has increased, data traffic and network instability have occurred, and data is transmitted using the same frequency, A phenomenon may occur that affects other vehicles in this adjacent location.

1 is a view for explaining a problem of a conventional vehicular communication apparatus.

1, the conventional vehicle communication device is configured such that the infrastructure 100 is configured so that the vehicle 21 and the vehicle 22 travel in the same direction in the same lane, The vehicle 22 is subject to communication interference within the cell by the adaptive beam B1 of the vehicle 21 when simultaneously forming the adaptive beams B1 and B2 towards the vehicle 22. [

The direction of the adaptive beam B3 formed toward the vehicle 23 in the state in which the vehicle 23 and the vehicle 24 travel in the same direction in the adjacent lane and the direction of the adaptive beam B3 B4 are identical, the vehicle 23 and the vehicle 24, respectively, can receive communication interference within the cell by the adaptive beams B4, B3.

(Patent Literature)

Korean Published Patent No. 2011-0135030 (Published on July 07, 2011)

That is, conventionally, there is a problem that the adaptive beam formed toward a vehicle induces communication interference in a cell affecting another vehicle, thereby reducing the capacity of the communication system.

Therefore, the present invention applies an adaptive beam-based beam-division multiple access scheme in a smart antenna-based vehicle communication apparatus in which an infrastructure exists, and detects an interference within a cell in which a beam formed toward a vehicle affects another vehicle And to provide a vehicle communication device capable of maximizing the capacity of a communication system by controlling a beam allocation and beam power for mitigating the above-mentioned problems, and a communication method therefor.

The present invention provides a vehicle communication device having an antenna having a single cell as a communication coverage, comprising: a communication unit for transmitting and receiving data to and from a plurality of vehicles in the cell; and a communication unit A beam allocation unit for allocating an adaptive beam in the direction of the selected vehicle, and a beam power allocator for controlling the size of the beam power according to the magnitude of the communication interference in the cell for the selected vehicle.

Also, the beam allocator selects a vehicle having the largest signal-to-noise interference ratio of the communication link for each vehicle among the plurality of vehicles as the vehicle with the least communication interference. The beam allocation unit allocates two or less vehicles to each adaptive beam.

The beam power allocator increases the beam power when communication interference in the cell with respect to the selected vehicle decreases. Here, the beam power allocating unit allocates the adaptive beam having a power greater than 0 and the total power of the adaptive beam smaller than a maximum beam power.

According to another aspect of the present invention, there is provided a communication method for a vehicle communication apparatus having an antenna having a single cell as a communication coverage, the method comprising: selecting one vehicle among the plurality of vehicles in the cell having the least communication interference; Allocating an adaptive beam to the selected vehicle and controlling the magnitude of the beam power according to the magnitude of communication interference in the cell for the selected vehicle.

The step of allocating the adaptive beam may include selecting a vehicle having the largest signal-to-noise interference ratio among the plurality of vehicles as the vehicle with the least communication interference.

The step of controlling the size of the beam power may include an initializing step of dividing the maximum transmittable beam power by the total number of the adaptive beams so that the beam power is uniformly allocated and the communication interference in the cell for the selected vehicle is reduced And increasing the beam power.

The present invention relates to a vehicle communication device and a communication method thereof, in which an adaptive beam-based beam-division multiple access scheme is applied to a smart antenna-based communication system in which an infrastructure exists and a beam formed toward a vehicle is influenced It is possible to maximize the capacity of the communication system by mitigating communication interference within the cell.

1 is a view for explaining a problem of a conventional vehicular communication device.
2 is a conceptual block diagram showing a vehicle communication device according to an embodiment of the present invention;
3 is a diagram for explaining a communication method of a vehicle communication device according to an embodiment of the present invention.

The following detailed description of the invention refers to the accompanying drawings, which illustrate, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with an embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly explained. In the drawings, like reference numerals refer to the same or similar functions throughout the several views.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention.

2 is a conceptual block diagram showing a vehicle communication device according to an embodiment of the present invention.

Referring to Fig. 2, the vehicle communication apparatus of the present invention includes an infrastructure 200. Fig. The infrastructure 200 according to the embodiment of the present invention simultaneously allocates the adaptive beams of the same frequency band to a plurality of vehicles located at different positions to transmit and receive data. Here, one communication coverage area of the infrastructure 200 is defined as a cell. The infrastructure 200 includes a communication unit 210, a beam allocation unit 220, and a beam power allocation unit 230. The communication unit 210 transmits and receives data to and from a plurality of vehicles located in the cell, including an antenna. Specifically, the communication unit 210 periodically receives the position, the moving speed, the channel state information, and the like of each vehicle through a GPS (Global Positioning System) included in each of the plurality of vehicles, Management, and user information applications.

The beam allocating unit 220 selects one of the plurality of vehicles located in the cell with the least communication interference, and allocates the adaptive beam in the direction of the selected vehicle. In addition, the beam power allocator 230 controls the size of the beam power according to the magnitude of the communication interference in the cell for the selected vehicle.

Hereinafter, a communication method of the vehicle communication device according to the embodiment of the present invention will be described with reference to FIG.

3 is a diagram for explaining a communication method of a vehicle communication device according to an embodiment of the present invention. Here, the vehicle (k, m) shown in Fig. 3 runs in one direction in the same lane, arrows indicated by solid lines represent signal channels, and arrows indicated by dotted lines represent interference channels.

First, for convenience of explanation, the infrastructure 200 is represented by i. Then, there are a total of K vehicles connected to the infrastructure i among the plurality of vehicles located in the cell, and the set is K = {1, ... , K}. The number of adaptive beams that can be allocated by the beam allocating unit 220 is a maximum of B, and a set of the adaptive beams is B = {1, ..., , B}. Also, one frame is composed of N downlink time slots, and a set of N = {1, ... , N}.

And, when adaptive beam b is allocated from infrastructure i to vehicle k in time slot n, the signal to interference plus noise ratio (SINR) of communication link k to vehicle k is (1) " That is, the signal-to-noise interference ratio? Of the cell with respect to the vehicle k increases as the interference in the cell by the other vehicle becomes smaller.

은 타임 슬롯 n에서 적응성 빔(b)에 할당된 전송 빔 파워를 나타낸다. 또한,

는 차량(k)에 대한 신호 채널 이득을 나타낸다. 여기서, θ(b,k)는 적응성 빔(b)의 방향과 차량(k)의 방향 사이의 각도를 나타낸다. 도 3의 경우, 차량(k)의 방향으로 적응성 빔(b)이 형성되어 있기 때문에, θ(b,k)=0을 만족한다. 여기서, θ(b,m)은 적응성 빔(b)의 방향과 차량(m)의 방향 사이의 각도를 의미하며, θ(b,m)=α를 만족한다. 그리고, 차량 k가 인프라 i를 통해 다른 차량(m)에 형성된 적응성 빔 a에 의해 간섭 채널이 형성되는 경우 간섭 채널 이득은

으로 정의된다. 즉, 차량(m)에 의한 셀 내부에서의 통신 간섭

은 적응성 빔 a의 전송 파워

와 차량 k에서의 간섭 채널 이득

의 곱에 대응하는 크기로 발생할 수 있다. Here,? ² represents the thermal noise power,

Represents the transmit beam power assigned to the adaptive beam b in time slot n. Also,

Represents the signal channel gain for vehicle k. Here,? (B, k) represents the angle between the direction of the adaptive beam b and the direction of the vehicle k. In the case of Fig. 3, since the adaptive beam b is formed in the direction of the vehicle k,? (B, k) = 0 is satisfied. Here,? (B, m) means an angle between the direction of the adaptive beam b and the direction of the vehicle m, and satisfies? (B, m) =?. And, when the interference channel is formed by the adaptive beam a formed on the other vehicle m through the infrastructure i, the interference channel gain k

. That is, the communication interference in the cell by the vehicle m

Lt; RTI ID = 0.0 > a < / RTI &

And the interference channel gain in the vehicle k

As shown in FIG.

Therefore, the beam allocating unit 220 can determine the vehicle with the least communication interference in the cell by using the signal-to-interference noise ratio [gamma]. That is, the beam allocating unit 220 can adaptively adapt the vehicle k to the vehicle k when the vehicle having the largest signal-to-interference noise ratio y, such as the vehicle k, And allocates the beam b.

At this time, the beam allocating unit 220 has constraint conditions as shown by the following equations (1.1) and (1.2). That is, the beam allocating unit 220 allocates one adaptive beam to one or less vehicles.

[Formula 1.1]

[Formula 1.2]

는 차량(k)에 대한 적응성 빔(b)의 할당 상태를 나타낸다. 예컨대, 타임 슬롯 n에서 적응성 빔(b)이 차량(k)에 할당되어 있으면,

는 1을 만족하고, 아니면 0을 만족한다. here,

Represents the allocation state of the adaptive beam b to the vehicle k. For example, if adaptive beam b in time slot n is assigned to vehicle k,

Satisfies 1, or 0 otherwise.

Meanwhile, the beam power allocating unit 230 allocates the transmission beam power p as shown in the following Equation (3).

을 의미하고,

은 타임 슬롯 n에서 적응성 빔(b)이 다른 통신 링크들을 발생시키는 셀 내 간섭의 양에 비례하는 누적 값을 나타내며, 아래의 [수학식 4]에 의해 정의된다. Here,

Lt; / RTI >

Represents an accumulated value proportional to the amount of intra-cell interference in which the adaptive beam b in time slot n generates other communication links, and is defined by Equation (4) below.

Further,? Denotes a ratio of vehicles arriving per unit time, and has a value of 0 or more. Equation (3) uses a water-filling algorithm, where the first term refers to the reference value of the transmission power, i.e., the water level, and the second term refers to the signal-to-noise interference ratio y). That is, the water-filling algorithm can be defined by the difference between the reference value of the transmission power and the reciprocal of the signal-to-noise interference ratio? Of the communication link to the vehicle k. Accordingly, when the interference in the cell for the adaptive beam b decreases, or when the signal-to-noise interference ratio gamma of the communication link for the vehicle k increases, the beam power allocator 230 allocates the adaptive beam b, Lt; / RTI >

At this time, the beam power allocating unit 230 must satisfy the constraint conditions (1.3) and (1.4) below for the maximum beam power.

[Formula 1.3]

[Formula 1.4]

Equation (1.3) indicates that the transmission power of each adaptive beam must be at least 0, and Equation (1.4) indicates that the total transmission power allocated to the adaptive beam should not be greater than the maximum beam power Pmax of the infrastructure 200 will be.

Hereinafter, the procedure of beam and beam power allocation according to the embodiment of the present invention will be described in each step on the basis of the above-described equations.

Initialization phase

First, the allocation of the beam power p is initialized. Then, beam allocation is performed to the vehicle having the highest signal-to-noise selection ratio among a plurality of vehicles in accordance with Equation (2).

Next, t is calculated according to Equation (4) based on the initial beam power and beam allocation.

Beam power and beam allocation update  step

First, the beam power allocation p is updated according to Equation (3).

And then updates the allocation of the adaptive beam b based on the updated beam power p. Then, when beam power and beam allocation are updated, t is updated. In this way, the initialization and updating process is repeated.

However, since the above process requires a complicated mathematical calculation, it is preferable to allocate the beam and beam power by the following heuristic method.

Initialization phase

First, the allocation of the beam power p is initialized, and the beam power p is equally allocated by dividing the maximum transmittable power Pmax by the total number of the adaptive beams.

Beam allocation step

Based on the initialized beam power p, beam allocation is performed to a vehicle having the highest signal-to-noise selection ratio among a plurality of vehicles according to Equation (2).

Beam power allocation step

The beam power is allocated according to Equation (3).

As described above, the vehicular communication device and the communication method according to the present invention use adaptive beam-based beam division multiple access (ICA) in a smart antenna-based communication system, And the beam allocation method for selecting the vehicle with the highest ratio and transmitting the data is applied. Further, a method of controlling the beam power in accordance with a signal-to-noise interference ratio of a communication link or a cell in which a beam formed toward a selected vehicle affects another vehicle is applied. Thus, the beam formed toward one vehicle can mitigate the interference within the cell affecting other vehicles, and maximize the capacity of the communication system.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Therefore, the spirit of the present invention should not be construed as being limited to the above-described embodiments, and all of the equivalents or equivalents of the claims, as well as the following claims, I will say.

200: Infrastructure
210:
220: beam allocation unit
230: beam power allocation unit

Claims (8)

An apparatus for communicating with a vehicle having an antenna having one cell as a communication coverage,
A communication unit for transmitting and receiving data with a plurality of vehicles in the cell;
A beam allocator for selecting one of the plurality of vehicles having the least communication interference in the cell and allocating an adaptive beam in a direction of the selected vehicle; And
And a beam power allocator for controlling the size of the beam power according to the magnitude of the communication interference in the cell for the selected vehicle,
Wherein the beam allocator selects a vehicle having the largest signal-to-noise interference ratio of the communication link for each vehicle among the plurality of vehicles as the vehicle with the least communication interference,
The signal-to-noise interference ratio may be expressed by the following equation

(here,

B is the adaptive beam, k is the vehicle connecting to the antenna,

Is the transmit beam power assigned to the adaptive beam b in time slot n,

(b, k) is the angle between the direction of the adaptive beam b and the direction of the vehicle k,

Is the signal channel gain for vehicle k,

Communication interference within the cell)
Is defined as < RTI ID = 0.0 > a < / RTI >
delete The method according to claim 1,
Wherein the beam allocating unit allocates one or more vehicles for each adaptive beam.
The method according to claim 1,
Wherein the beam power allocating unit increases the beam power when communication interference in the cell for the selected vehicle decreases.
The method according to claim 1,
Wherein the beam power allocating unit assigns the power of the adaptive beam to be larger than 0 and the total power of the adaptive beam to be smaller than the maximum beam power.
A communication method of a vehicle communication apparatus having an antenna having one cell as a communication coverage,
Selecting one of the plurality of vehicles in the cell with the least communication interference in the cell and allocating the adaptive beam in the direction of the selected vehicle; And
Controlling the magnitude of the beam power according to the magnitude of communication interference in the cell for the selected vehicle,
Wherein the step of allocating the adaptive beam includes selecting a vehicle having the largest signal-to-noise interference ratio of the communication links among the plurality of vehicles as the vehicle with the least communication interference,
The signal-to-noise interference ratio may be expressed by the following equation

(here,

B is the adaptive beam, k is the vehicle connecting to the antenna,

Is the transmit beam power assigned to the adaptive beam b in time slot n,

(b, k) is the angle between the direction of the adaptive beam b and the direction of the vehicle k,

Is the signal channel gain for vehicle k,

Communication interference within the cell)
Of the vehicle communication device.
delete The method according to claim 6,
The step of controlling the magnitude of the beam power comprises:
Dividing the maximum transmittable beam power by the total number of the adaptive beams and allocating the beam power equally; And
And increasing the beam power when communication interference within the cell for the selected vehicle is reduced.

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