KR101407815B1 - Device and Method for Enhancing Communication Capacity in Device to Device Communication - Google Patents

Abstract

A device and a method for enhancing a communication capacity in device-to-device communications are disclosed. The method comprises the steps of: determining a maximum allowable signal-to-interference ratio for securing a minimum communication capacity in a device-to-device communications system; setting an interference limited region on the basis of a terminal receiving signals among one pair of terminals performing device-to-device communications using the determined maximum allowable signal-to-interference ratio; and selecting at least one cellular terminal to share resources with the one pair of terminals performing the device-to-device communications in consideration of the interference limited region. According to the present invention, it is possible to prevent reduction of the communication capacity caused by interference when multiple cellular terminals and device-to-device communication terminals share the same resources, thereby increasing a communication system capacity.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and apparatus for improving communication capacity in communication between devices,

Embodiments of the present invention relate to inter-device communication, and more particularly, to a method and apparatus for improving communication capacity in a communication system to which inter-device communication is applied.

A general communication system transmits and receives data through a fixed base station (BS) for communication between a mobile station (MS) and a mobile station. However, when a pair of terminals desiring to communicate with each other is located at a close position, the base station transmits / receives only the control signal to / from each terminal, and the actual data signal shares the frequency resource with the cellular network without going through the base station, A device-to-device (D2D) communication system is being studied.

Since the inter-device communication system shares frequency resources with the cellular network, the overall communication capacity can be improved and the data throughput rate of the terminal using the inter-device communication mode can be improved as compared with the conventional cellular method of transmitting through the base station. That is, for a pair of terminals located close to each other, the base station supports the inter-device communication mode, thereby enabling higher-speed data to be transmitted, and the overall frequency efficiency through frequency re-use of the inter-device communication user can be increased.

However, in the inter-device communication system, when a plurality of cellular terminals and a pair of communication terminals share the same resource, in order to improve the communication capacity of the inter-device communication system, interference caused by frequency reuse occurs, .

Therefore, efficient interference control technology is needed to increase the communication capacity of the inter-device communication system without a large loss in the total communication capacity of the cellular terminals.

개의 셀룰러 단말기중

개의 셀룰러 단말기를 지원하는 셀룰러 네트워크와 한 쌍의 기기간 통신 단말기가 같은 자원을 공유할 때, 데이터 신호와 간섭 신호를 도시한 도면이다.FIG.

Of the cellular terminals

1 illustrates a data signal and an interference signal when a cellular network supporting two cellular terminals and a pair of communication terminals share the same resource.

개의 다중 안테나를 장비한 기지국(BS),

개의 셀룰러 단말기 (

), 제 1 기기간 통신 단말기(

), 및 제 2 기기간 통신 단말기(

)를 포함하여 구성된다. 이 때,

는

보다 크다고 가정한다.Referring to FIG. 1, an inter-device communication system sharing frequency resources of a cellular network

A base station (BS) equipped with multiple antennas,

Cellular terminals (

), The first inter-device communication terminal (

) And the second device-to-device communication terminal (

). At this time,

The

.

개의 다중 안테나를 이용하여 상기

개의 셀룰러 단말기 중 최대

개의 셀룰러 단말기를 다중-입력 다중-출력 기법을 이용하여 동시에 지원한다.The base station

Lt; RTI ID = 0.0 >

Of cellular handsets

And supports multiple cellular terminals simultaneously using a multi-input multiple-output scheme.

개의 셀룰러 단말기와 주파수 자원을 공유한다.The first inter-device communication terminal and the second inter-device communication terminal, which are terminal pairs located in close proximity, transmit and receive data signals in the inter-device communication mode in accordance with the control signal of the base station. At this time,

And shares frequency resources with the cellular terminals.

개의 셀룰러 단말기와 같은 주파수 자원을 이용하여 신호를 전송하기 때문에, 상기 기지국에서 수신하는 신호에는 상기 제 1 기기간 단말기에 의한 간섭 신호가 포함될 수 있다. 그러나 기기간 통신 시스템의 특성상 상기 제 1 기기간 단말기의 송신 전력은 엄격히 제한 됨으로 인해 상기 제 1 기기간 단말기에 의한 기지국에서의 간섭 신호는 무시될 수 있다.In the uplink, the first inter-device communication terminal

Since signals are transmitted using the same frequency resources as the cellular terminals, the signal received by the base station may include an interference signal from the first inter-device terminal. However, due to the characteristics of the inter-device communication system, the transmission power of the first inter-device terminal is strictly limited, so that the interference signal at the base station by the first inter-device terminal can be ignored.

개의 셀룰러 단말기에 의한 간섭 신호를 동시에 포함한다. 따라서 상기 제 2 기기간 통신 단말기는

개의 셀룰러 단말기에 의한 간섭 신호를 효율적으로 처리해주어야 기기간 통신 시스템의 통신 용량을 향상 시킬 수 있다.When receiving the desired signal from the first inter-device communication terminal and the second inter-device communication terminal in the uplink,

Lt; RTI ID = 0.0 > cellular < / RTI > Therefore, the second inter-device communication terminal

It is possible to improve the communication capacity of the inter-device communication system by efficiently processing the interference signals by the two cellular terminals.

In order to solve the problems of the related art as described above, the present invention provides a method and apparatus for improving the capacity of a communication system by preventing communication capacity degradation due to interference when a plurality of cellular terminals and a communication terminal between devices share the same resources Lt; / RTI >

In order to achieve the above object, according to a preferred embodiment of the present invention, there is provided a method performed by a base station for improving communication capacity in inter-device communication, the method comprising: determining a maximum allowable interference- (A); (B) setting an interference restricting region based on a terminal receiving a terminal pair signal for performing communication between devices using the determined maximum allowed interference to signal ratio; And a step (c) of selecting at least one cellular terminal to share resources with a terminal pair performing the inter-device communication in consideration of the interference restricting region.

In the step (c), when at least one cellular terminal to share the resources is selected, the cellular terminals existing in the interference limiting region are excluded from the selection target and selected.

The maximum allowed interference to signal ratio is determined using the average received signal power of the link of the terminal pair performing the inter-device communication.

The interference restricting area is a circular area having a predetermined radius based on the terminal receiving the signal of the terminal pair performing the inter-device communication.

According to another aspect of the present invention, there is provided a base station apparatus for improving communication capacity in inter-device communication, comprising: a maximum allowable interference-to-signal ratio decision unit for determining a maximum allowable interference-to-signal ratio for ensuring a minimum communication capacity in an inter-device communication system; An interference restricting region setting unit for setting an interference restricting region based on a terminal receiving a terminal pair signal for performing inter-device communication using the determined maximum allowed interference to signal ratio; And a resource allocator configured to allocate a resource of the selected terminal to the pair of terminals selected by selecting at least one cellular terminal to share resources with the terminal pair performing the inter-device communication in consideration of the interference restriction area do.

According to the present invention, there is an advantage that, when a plurality of cellular terminals and a communication terminal between devices share the same resources, the communication capacity can be improved by preventing a decrease in communication capacity due to interference.

개의 셀룰러 단말기중

개의 셀룰러 단말기를 지원하는 셀룰러 네트워크와 한 쌍의 기기간 통신 단말기가 같은 자원을 공유할 때, 데이터 신호와 간섭 신호를 도시한 도면.
도 2는 상향 링크 기간에

개의 셀룰러 단말기와 한 쌍의 기기간 통신 단말기(D1, D2)가 주파수 자원을 공유할 때 발생하는 간섭 및 본 발명에서 제안되는 간섭 제한 영역을 도시한 도면.
도 3은 본 발명의 일 실시예에 따른 기기간 통신 시스템의 통신 용량을 향상시키기 위한 방법의 전체적인 흐름을 도시한 순서도.
도 4는 상기 수학식 10에 의한 상기 간섭 제한 영역 중 A>1인 경우의 간섭 제한 영역을 도시한 도면.
도 5는 본 발명의 일 실시예에 따라 기기간 단말기와 자원을 공유할 셀룰러 단말기를 선택하는 일례를 도시한 도면.FIG.

Of the cellular terminals

A data signal and an interference signal when a cellular network supporting two cellular terminals and a pair of communication terminals share the same resource.
Fig. 2 is a diagram

(D 1, D 2) of a cellular terminal and a pair of inter-device communication terminals (D 1, D 2) share a frequency resource, and interference restriction areas proposed in the present invention.
3 is a flowchart showing a general flow of a method for improving communication capacity of an inter-device communication system according to an embodiment of the present invention;
4 is a view showing an interference restricting region when A> 1 among the interference restricting regions according to Equation (10).
5 is a diagram illustrating an example of selecting a cellular terminal to share resources with an inter-device terminal according to an embodiment of the present invention;

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

개의 셀룰러 단말기와 한 쌍의 기기간 통신 단말기(D1, D2)가 주파수 자원을 공유할 때 발생하는 간섭 및 본 발명에서 제안되는 간섭 제한 영역을 도시한 도면이다.Fig. 2 is a diagram

FIG. 5 is a diagram illustrating an interference occurring when two cellular terminals and a pair of inter-device communication terminals D1 and D2 share frequency resources, and an interference restriction region proposed in the present invention.

과

개의 셀룰러 단말기에 의해 발생하는

개의 간섭 신호를 수신하게 된다. 이 때,

번째 셀룰러 단말기로부터 상기 제 2 기기간 통신 단말기로 수신되는 간섭 신호를

라고 표기하면 상기 제 2 기기간 통신 단말기(D2)에서 수신 되는 신호는 수학식 1과 같다.Referring to FIG. 2, the second device-to-device communication terminal D2 transmits a desired signal

and

Lt; RTI ID = 0.0 >

Lt; / RTI > interference signals. At this time,

Lt; RTI ID = 0.0 > inter-cellular < / RTI > communication terminal

The signal received by the second inter-device communication terminal D2 is expressed by Equation (1).

와

는 각각 상기 제 1 기기간 통신 단말기와 상기 제 2 기기간 통신 단말기 링크의 채널 계수 및 상기

번째 셀룰러 단말기와 상기 제 2 기기간 통신 단말기(D2) 링크의 채널 계수를 의미한다. 그리고

와

는 각각 상기 제 1 기기간 통신 단말기(D1)의 전송 파워 및

번째 셀룰러 단말기의 전송파워를 의미한다. 그리고

와

는 각각 상기 제 1 기기간 통신 단말기(D1)와 상기 제 2 기기간 통신 단말기(D2) 사이의 거리와 상기

번째 셀룰러 단말기와 상기 제 2 기기간 통신 단말기(D2) 사이의 거리를 의미한다. In Equation (1)

Wow

And the channel coefficient of the link between the first inter-device communication terminal and the second inter-device communication terminal,

Th cellular terminal and the communication terminal D2 between the second cellular terminal and the second apparatus. And

Wow

(D1) and the transmission power of the communication terminal

Th < / RTI > cellular terminal. And

Wow

Between the first inter-device communication terminal (D1) and the second inter-device communication terminal (D2)

Th cellular terminal and the communication terminal D2 between the second cellular terminal and the second device.

는 경로 손실 상수,

는 경로 손실 지수를 의미한다. 또한,

는 제 2 기기간 통신 단말기에서의 잡음을 의미한다.Equation (1) assumes a free space path loss model

Is a path loss constant,

Means the path loss index. Also,

Means the noise in the communication terminal between the second devices.

Referring to FIG. 2, the present invention establishes an interference restricting area based on a second inter-device communication terminal D2 that is a terminal for receiving a signal among inter-device communication terminals. If the transmission / reception relationship of the communication terminal between devices is changed (i.e., when the first communication terminal D1 becomes the receiving terminal), the interference restriction area is set based on the first communication terminal D1.

According to a preferred embodiment of the present invention, in the present invention, a cellular terminal to share a frequency resource is selected using an interference restriction area as shown in FIG. 2, and selection is made by a base station (BS)

When selecting a terminal to share a frequency resource, the base station selects a part of the cellular terminals outside the interference restriction area as a terminal to share the frequency resource, and excludes the cellular terminals in the interference restriction area from the selection target.

Hereinafter, a process of setting an interference restriction area based on a receiving terminal in the inter-device communication terminal and selecting the cellular terminals to share the paging resource will be described in more detail.

3 is a flowchart illustrating an overall flow of a method for improving communication capacity of an inter-device communication system according to an embodiment of the present invention.

Referring to FIG. 3, the BS acquires the average received signal-to-noise ratio information of the first inter-device communication terminal D1 and the second device communication terminal D2 link (step 200).

The average received signal power of the first inter-device communication terminal D1 and the second inter-device communication terminal D2 is defined by Equation (2).

The base station BS uses the average received signal power information of the obtained first inter-device communication terminal D1 and the second inter-device communication terminal D2 to determine the maximum allowable interference band for ensuring the minimum communication capacity of the inter- Signal ratio (step 202).

Hereinafter, a process of calculating the minimum communication capacity of the communication system according to the maximum allowable interference-to-signal ratio to calculate the maximum allowed interference-to-signal ratio will be described.

번째 셀룰러 단말기로부터 제 2 기기간 통신 단말기(D2)로 발생하는 간섭 신호에 대한 평균 수신 간섭 파워는 다음의 수학식 3과 같이 정의된다.

The average reception interference power for the interference signal generated from the second cellular communication terminal D2 to the second communication terminal D2 is defined as Equation (3).

번째 셀룰러 단말기로부터 기지국(BS)으로 수신되는 신호의 평균 수신 파워는 다음의 수학식 4와 같다.Assuming that all the cellular terminals in the cellular network are controlled to have the same received power level at the base station (BS)

Th cellular terminal to the base station (BS) is given by Equation (4). &Quot; (4) "

는 각각의 셀룰러 단말기로부터 기지국(BS)으로 수신되는 수신 신호의 평균 파워 레벨을 의미하고,

는

번째 셀룰러 단말기와 상기 기지국(BS) 사이의 거리를 의미한다.In Equation (4)

Means an average power level of a reception signal received from each of the cellular terminals to a base station (BS)

The

Th < / RTI > cellular terminal and the base station (BS).

번째 셀룰러 단말기로부터 수신되는 간섭 신호에 간섭 대 신호 비를

라고 표기한다.The second communication terminal D2 as the receiving terminal

Th < / RTI > cellular terminal to the interfering signal ratio

.

At this time, a set of positions where the cellular terminal generates an interference-to-signal ratio exceeding the maximum allowable interference-to-signal ratio determined at the base station (BS) is defined as an interference limiting region. That is, an area satisfying the condition of the following equation (5) is set as the interference restricting area.

는 기기간 통신 단말기 쌍이 허용할 수 있는 최대 간섭 대 신호 비를 의미한다. 상기 수학식 5를 상기 수학식 1에 대입하면, 상기 간섭 제한 영역을 이용할 때 제 2 기기간 통신 단말기(D2)의 수신 신호 대 잡음 비의 하계(lower bound)는 수학식 6와 같이 표현 할 수 있다.In Equation (5)

Means the maximum interference-to-signal ratio that a pair of communication terminal units can allow. When Equation (5) is substituted into Equation (1), the lower bound of the received signal-to-noise ratio of the second inter-device communication terminal (D2) can be expressed by Equation (6) .

개의 셀룰러 단말기가 모두 상기 간섭 제한 영역의 가장자리에 위치하는 최악 상황 시나리오를 가정했을 때의 제 2 기기간 통신 단말기의 수신 신호 대 잡음 비를 의미한다. 즉, 상기 간섭 제한 영역을 이용할 때 제 2 기기간 통신 단말기가 받을 수 있는 최대 간섭 파워를 가정했을 때의 수신 신호 대 잡음 비를 나타낸다.Equation (6) can be expressed as Equation (6)

Means a signal-to-noise ratio of a communication terminal of a second device when assuming a worst-case scenario in which all of the cellular terminals are located at the edge of the interference-limited area. That is, it represents a received signal-to-noise ratio when assuming the maximum interference power that can be received by the second-device communication terminal when the interference restricting area is used.

Assuming that the wireless channel of each link follows the Rayleigh fading channel in Equation (6), the summer of the average communication capacity can be expressed by Equation (7).

는 hyper-geometric 함수를 의미한다. 그리고 상기 수학식 7은 기기간 통신 단말기 쌍이

개의 셀룰러 단말기와 주파수 자원을 공유할 때, 상기 간섭 제한 영역 기법을 적용하였을 때 기기간 통신 단말기 쌍이 얻을 수 있는 최소 통신 용량을 의미한다.In Equation (7)

Is a hyper-geometric function. And Equation (7) is obtained by using Equation

Refers to the minimum communication capacity that a pair of communication terminal units can obtain when the interference limiting area technique is applied when sharing frequency resources with two cellular terminals.

를 결정한다.The maximum allowable interference-to-signal ratio for ensuring the minimum communication capacity of the inter-device communication system by Equation (7)

.

를 이용하여 상기 간섭 제한 영역을 설정한다(단계 204). The base station (BS) calculates the maximum allowed interference to signal ratio,

To set the interference restricting area (step 204).

Substituting Equation (3) and Equation (4) into Equation (5), the condition of the interference-limited region can be expressed again as Equation (8).

, 상기

번째 셀룰러 단말기의 위치를

,그리고 상기 제 2 기기간 통신 단말기의 위치를

라고 하면 상기 수학식 8은 수학식 9과 같이 다시 표현할 수 있다.The location of the base station

, remind

Lt; th >

, And the position of the communication terminal between the second device

Equation (8) can be rewritten as Equation (9).

로 치환하면, 상기 간섭 제한 영역은

에 따라 수학식 10과 같이 3가지 경우로 표현할 수 있다.In Equation (9)

, The interference restricting region

As shown in Equation (10).

FIG. 4 is a diagram showing an interference restricting region when A> 1 among the interference restricting regions according to Equation (10).

일 때에는 상기 간섭 제한 영역은 중심이

이고, 반지름이

인 원의 안쪽 영역이 된다. 반면,

일 때에는 같은 형태의 중심과 반지름을 가진 원의 바깥 영역이 된다. 그리고

일 때는 셀룰러 네트워크의 셀이 상기 기지국과 상기 제 2 기기간 통신 단말기 사이의 중심점을 지나는 직선에 의해 나누어 질 때, 더 큰 영역이 상기 간섭 제한 영역이 된다.Referring to Figure 4,

The interference restricting region is centered

And the radius

It is the inner area of the circle. On the other hand,

It becomes the outer region of a circle with the same center and radius. And

, When a cell of the cellular network is divided by a straight line passing through a center point between the base station and the second device communication terminal, a larger area becomes the interference restricting area.

인 경우 및

인 경우는 통신 용량 향상이 불가능한 경우로서 고려하지 않는다.

And

, It is not considered that the communication capacity improvement is impossible.

일 때가 다른 2 가지 경우와 비교할 때, 셀룰러 네트워크 관점에서 통신 용량 손실을 줄일 수 있다. 또한,

이므로, 기기간 통신의 평균 수신 신호 파워,

는

에 비해 제 1 기기간 통신 단말기(D1)와 제 2 기기간 통신 단말기(D2)의 인접한 거리에 의해 매우 크다고 가정할 수 있다. 따라서

임을 가정하면, 간섭 제한 영역은 중심이

이고, 반지름이

인 원의 안쪽 영역이 된다.In the interference limiting area, a method of not sharing the frequency of the communication terminal between the cellular terminal and the device is used. Therefore, as the area of the interference limiting area increases, the degree of freedom of the scheduling of the cellular terminal decreases in the cellular network. It is possible to reduce the communication capacity. therefore

When compared to the other two cases, it is possible to reduce the communication capacity loss in terms of the cellular network. Also,

The average received signal power of the inter-device communication,

The

It can be assumed that the distance between the first communication terminal D1 and the second communication terminal D2 is very large. therefore

, The interference limiting region is centered

And the radius

It is the inner area of the circle.

개의 셀룰러 단말기를 선택하며, 이 때, 간섭 제한 영역 안에 존재하는 셀룰러 단말기는 셀룰러 단말기 선택에서 제외된다(단계 206). A base station may share frequency resources with a pair of terminals

The cellular terminals existing in the interference restriction area are excluded from the cellular terminal selection (step 206).

5 is a diagram illustrating an example of selecting a cellular terminal to share resources with an inter-device terminal according to an embodiment of the present invention.

Referring to FIG. 5, there are two cellular terminals C1 and C2 in the interference restriction region, and four cellular terminals C3, C4, C5, and C6 exist outside the interference restriction region.

According to an embodiment of the present invention, at least one of C3, C4, C5, and C6 located outside the interference restriction region is selected as a cellular terminal sharing resources with the inter-device terminals D1 and D2, And the resources to be used are shared by the inter-device terminals D1 and D2.

As described above, the present invention has been described with reference to particular embodiments, such as specific elements, and specific embodiments and drawings. However, it should be understood that the present invention is not limited to the above- And various modifications and changes may be made thereto by those skilled in the art to which the present invention pertains. Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

Claims (8)

A method performed at a base station for improving communication capacity in communication between devices,
(A) determining a maximum allowable interference-to-signal ratio for ensuring a minimum communication capacity in the inter-device communication system;
(B) setting an interference restricting region based on a terminal receiving a terminal pair signal for performing communication between devices using the determined maximum allowed interference to signal ratio; And
(C) selecting at least one cellular terminal to share resources with a pair of terminals performing the inter-device communication in consideration of the interference restriction area,
Wherein the step (c) includes selecting the at least one cellular terminal to which the resource is to be shared by excluding the cellular terminals within the interference-restricted region from the selection target. delete The method according to claim 1,
Wherein the maximum allowed interference to signal ratio is determined using an average received signal power of a link of a terminal pair performing the inter-device communication. The method according to claim 1,
Wherein the interference restricting area is a circular area having a predetermined radius based on a terminal receiving a signal of the terminal pair performing the inter-device communication. A base station apparatus for improving communication capacity in communication between apparatuses,
A maximum allowable interference-to-signal ratio decision unit for determining a maximum allowable interference-to-signal ratio for ensuring a minimum communication capacity in the inter-device communication system;
An interference restricting region setting unit for setting an interference restricting region based on a terminal receiving a terminal pair signal for performing inter-device communication using the determined maximum allowed interference to signal ratio; And
And a resource allocator configured to allocate resources of the selected terminal to the pair of terminals selected by selecting at least one cellular terminal to share resources with the terminal pair performing the inter-device communication in consideration of the interference restriction area,
Wherein the resource allocator selects and excludes the cellular terminals existing in the interference restriction area when selecting at least one cellular terminal to share the resources. delete 6. The method of claim 5,
Wherein the maximum allowed interference to signal ratio is determined using an average received signal power of a link of a terminal pair performing the inter-device communication. 6. The method of claim 5,
Wherein the interference restricting region is a circular region having a predetermined radius based on a terminal receiving a signal of the terminal pair performing the inter-device communication.

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