KR101207615B1 - Node and controll method for receiving signal for the same - Google Patents

Abstract

PURPOSE: A node and signal reception control method thereof are provided to minimize interference between a source node and a purpose node without reducing the whole communication capacity. CONSTITUTION: A node receives a wireless signal including a first signal and a second signal in an i-time section(S610). The node computes the communication capacity of a link between the node and a source node(S620). When the communication amount is smaller than the set threshold communication capacity, the node creates an interference signal(S630). The node broadcasts the interference signal without receiving the wireless signal in an i+1-time section(S640). The node repeats the reception step and non-reception step of the wireless signal from an i+2-time section(S650). [Reference numerals] (AA) Start; (BB) End; (S610) Receiving a wireless signal including a first signal and a second signal in an i-time section; (S620) Computing the communication capacity of a link between a node and a source node by using the reception strength of a first signal and a second signal; (S630) Creating an interference signal when communication capacity is smaller than the set threshold communication capacity; (S640) Broadcasting an interference signal without receiving a wireless signal in an i+1-time section; (S650) Repeating a reception step and a non-reception step of a wireless signal from an i+2-time section

Description

Node and its signal reception control method {NODE AND CONTROLL METHOD FOR RECEIVING SIGNAL FOR THE SAME}

Embodiments of the present invention relate to a node constituting a distributed network and a method for controlling signal reception thereof, and more particularly, to minimize interference at a plurality of source node-purpose node links without reducing overall communication capacity. It relates to a node and a method for controlling signal reception thereof.

In a distributed network such as the ad hoc network shown in FIG. 1, a source node (SN) and a destination node (DN) are paired to perform communication. That is, one source node transmits a radio signal using one target node as a target node. At this time, the radio signal transmitted from the source node is received as a desired radio signal in the target node paired with itself, but acts as an interference in another target node not paired with itself.

For example, when communication is performed by pairing SN1 and DN1, and pairing SN2 and DN2 with each other, the radio signal transmitted from SN1 acts as interference at DN2, and the radio signal transmitted from SN2 is DN1. Acts as interference in

In order to prevent such interference, conventionally, the SN1 and the SN2 exchange information with each other so as not to transmit a radio signal at the same time (that is, by transmitting time alternately with each other to minimize the interference).

However, the above-described prior art had to use an additional bit for SN1 and SN2 to exchange information with each other, thereby reducing the overall communication capacity.

Meanwhile, according to a cooperative transmission scheme in a distributed network, a source node first transmits a radio signal to cooperative nodes (CNs) located close to itself in a first time interval, and then communicates with a source node in a second time interval. The cooperative node simultaneously transmits the same radio signal to the destination node as the radio signal transmitted in the first time interval.

However, the interference phenomenon as described above also occurs in the transmission of a radio signal according to such a cooperative communication technique. For example, a signal that CN1 receiving data from SN1 transmits to DN1 may cause interference in DN2.

Therefore, there is a need to schedule signal transmission between the source node and the cooperative node so that interference is minimized even in the transmission of the radio signal according to the cooperative communication technique.

In order to solve the problems of the prior art as described above, the present invention proposes a node and its signal reception control method that can minimize the interference in a plurality of source node-purpose node link without reducing the overall communication capacity I would like to.

Other objects of the present invention may be derived by those skilled in the art through the following examples.

According to a preferred embodiment of the present invention to achieve the above object, in the signal reception control method of a node constituting a distributed network, transmitting from the source node of the node in the i th time interval (i is an integer of 1 or more) Receiving a wireless signal comprising a first signal transmitted and a second signal transmitted from at least one other node other than the source node in the distributed network; Calculating a communication capacity of a link between the node and the source node using the reception strength of the first signal and the reception strength of the second signal; Generating an interference signal when the communication capacity is less than a preset threshold communication capacity; broadcasting the interference signal without receiving the wireless signal in an i + 1th time interval; And repeating reception and non-reception of the radio signal from an i + 2 th time period.

Further, according to another embodiment of the present invention, in the method for controlling signal reception of a node constituting a distributed network, the first signal transmitted from a source node of the node and the first signal in an i th time interval (i is an integer of 1 or more) Receiving a wireless signal including a second signal transmitted from one or more other nodes other than the source node in a distributed network; The communication capacity of the link between the node and the source node in the i-th time interval by using the reception strength of the first signal and the reception strength of the second signal received in the i-th time interval (i-th communication capacity) Calculating; receiving the wireless signal in an i + ath time interval (a is an integer of 1 or more); The communication capacity of the link between the node and the source node in the i + a-th time interval by using the reception strength of the first signal and the reception strength of the second signal received in the i + a-th time interval (i calculating a + a th communication capacity; And repeating reception and non-reception of the radio signal from an i + a + 1th time interval when a change rate between the i th communication capacity and the i + a th communication capacity is greater than a preset communication capacity change rate. A signal reception control method of a node is provided.

Further, according to another embodiment of the present invention, in a node constituting a distributed network, a first signal transmitted from a source node of the node and the first signal transmitted in the i-th time interval (i is an integer of 1 or more) A receiver configured to receive a radio signal including a second signal transmitted from one or more other nodes other than the source node; A communication capacity calculator configured to calculate a communication capacity of a link between the node and the source node by using the reception strength of the first signal and the reception strength of the second signal; An interference signal generator for generating an interference signal when the communication capacity is smaller than a preset threshold communication capacity; And a transmitter configured to broadcast the interference signal in an i + 1th time interval, wherein the receiver does not receive the wireless signal in the i + 1th time interval, and from the i + 2th time interval, A node is provided that repeats receiving and not receiving.

According to the present invention, it is possible to minimize interference in multiple source node-purpose node links without reducing overall communication capacity.

1 is a diagram illustrating a general configuration of a distributed network.
2 is a block diagram illustrating a schematic configuration of a node according to an embodiment of the present invention.
3 to 5 are diagrams for describing a concept of a signal transmission / reception operation of nodes in a distributed network according to an embodiment of the present invention.
6 is a flowchart illustrating the overall flow of a method for controlling signal reception of a node constituting a distributed network according to an embodiment of the present invention.
7 is a flowchart illustrating the overall flow of a method for controlling signal reception of a node constituting a distributed network according to another 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 of the present invention will be described in detail with reference to the accompanying drawings.

2 is a diagram illustrating a schematic configuration of a node according to an embodiment of the present invention.

Referring to FIG. 2, a node 200 according to an embodiment of the present invention refers to an arbitrary node operable as a destination node among a plurality of nodes constituting a distributed network, and includes a receiver 210 and a communication capacity calculator. 220, an interference signal generator 230, and a transmitter 240. At this time, another node in the distributed network that can operate as the destination node may have the same configuration as the node 200 according to an embodiment of the present invention.

In the following description, for convenience of description, the node 200 will be referred to as a "first target node 200" and the source node paired with the node 200 will be referred to as a "first source node".

The function of each component is as follows.

The receiver 210 receives a radio signal transmitted from the outside. In more detail, the receiver 210 receives a radio signal for each time interval.

In this case, the received radio signal includes a signal transmitted from a first source node and a signal transmitted from one or more other nodes in a distributed network other than the first source node, and as described above, transmitted from one or more other nodes. The signal acts as interference to the signal transmitted at the first source node. Hereinafter, for convenience of description, a signal received by a specific target node from a source node paired with it is referred to as a "first signal", and is a signal received from a node other than the source node (that is, a signal acting as an interference). Will be referred to as the "second signal".

As an example, when the first source node transmits the first signal by itself, the wireless signal received through the receiver 210 may be expressed by Equation 1 below.

는 수신된 무선 신호,

는 제1 소스 노드에서 제1 신호를 전송하는데 소비된 전력(Power),

는 제1 소스 노드와 제1 목적 노드(200) 사이의

차원의 채널 매트릭스,

는 제1 소스 노드, 제1 목적 노드(200) 및 하나 이상의 다른 노드에 구비된 안테나의 개수,

(

)는 제1 소스 노드에서의

차원의 전송 가중치 벡터,

(

)는 제1 소스 노드에서 전송되는 제1 신호의 심볼,

는

차원의 잡음 벡터,

는

차원의 간섭 신호에 대한 벡터를 각각 의미한다. 이 때,

는 아래의 수학식 2와 같이 표현될 수 있다. here,

Is the received wireless signal,

Is the power consumed to transmit the first signal at the first source node,

Is between the first source node and the first destination node 200.

Dimensional channel matrix,

Is the number of antennas provided in the first source node, the first destination node 200 and one or more other nodes,

(

) At the first source node

Dimension transmission weight vector,

(

) Is a symbol of the first signal transmitted from the first source node,

The

Dimensional noise vector,

The

Means a vector for the interference signal of the dimension respectively. At this time,

May be expressed as Equation 2 below.

는 상기 하나 이상의 다른 노드의 집합,

는 하나 이상의 다른 노드 중 j번째 다른 노드에서 제2 신호를 전송하는데 소비된 전력,

는 j번째 다른 노드와 제1 목적 노드(200) 사이의

차원의 채널 매트릭스,

(

)는 j번째 다른 노드에서 전송된 제2 신호를 각각 의미한다. here,

Is a set of one or more other nodes,

Is the power consumed to transmit the second signal in the j-th other node of the one or more other nodes,

Is between the j th other node and the first destination node 200.

Dimensional channel matrix,

(

) Means each of the second signals transmitted from the j-th other node.

Next, the communication capacity calculator 220 may determine the link between the first destination node 200 and the first source node using the reception strengths of the first signal and the second signal included in the wireless signal received in each time interval. Calculate the communication capacity. The communication capacity is a parameter that indicates how efficiently the first target node 200 receives the first signal from the first source node.

According to an embodiment of the present invention, the communication capacity may be proportional to the reception strength of the first signal and inversely proportional to the reception strength of the second signal. As an example, the communication capacity may be expressed as Equation 3 below.

는 통신 용량,

는 수신부(210)를 통해 수신된 무선 신호의 SINR(Signal to Interference Noise Ratio)를 각각 의미하며,

는 아래의 수학식 4와 같이 표현될 수 있다.
here,

Is the communication capacity,

Denotes a Signal to Interference Noise Ratio (SINR) of the wireless signal received through the receiver 210, respectively.

May be expressed as Equation 4 below.

는 제1 목적 노드(200)에서 수신된 무선 신호를 복원하는데 사용되는 가중치 벡터로서,

와

는

를 특이값 분해(SVC: Singular Value Decomposition)하여 획득될 수 있다. 이 때,

와

는 유니터리 매트릭스(Unitary Matrix)이고,

는

의 특이값(Singular Value)를 원소로 가지는 대각 매트릭스(Diagonal Matrix)이다. 만약,

이고,

라면,

는

가 되고,

은

의 가장 큰 특이값이 된다. here,

Is a weight vector used to recover the radio signal received at the first destination node 200.

Wow

The

Can be obtained by singular value decomposition (SVC). At this time,

Wow

Is the Unitary Matrix,

The

It is a diagonal matrix having a singular value of as an element. if,

ego,

Ramen,

The

Become,

silver

Is the largest singular value of.

및

는 각각 아래의 수학식 5와 같이 표현된다.
Also,

And

Are each represented by Equation 5 below.

Subsequently, the interference signal generator 230 selectively generates the interference signal based on the communication capacity of the link calculated by the communication capacity calculator 220. More specifically, the interference signal generator 230 generates an interference signal when the calculated communication capacity is smaller than the preset threshold communication capacity. Here, the interference signal is a signal for notifying the neighboring nodes that the first destination node 200 has a low communication capacity of the link between itself and the first source node.

As an example, if a distributed network is configured as shown at the top of FIG. 3, and the first source node and the first destination node 200 correspond to SN1 and DN1, respectively, then in the i th time interval, DN1 is determined from SN1. At the same time as receiving one signal, a second signal is received from another source node SN2. At this time, since DN1 is located adjacent to SN2, the first signal received from SN1 is subjected to strong interference by the second signal received from SN2, so that the communication capacity of the link between SN1 and DN1 has a low value. do.

As another example, if a distributed network is configured as shown at the top of FIG. 4, and the first source node and the first destination node 200 correspond to SN1 and DN1, respectively, then DN1 is determined from SN1 in the i th time interval. At the same time as receiving the first signal, a second signal is received from another source node SN2. At this time, since DN1 is located away from SN2, the interference effect of the second signal transmitted from SN2 is small. However, since DN1 is located away from SN1, the reception strength of the first signal received from SN1 by signal attenuation has a small value. Therefore, even in this case, the communication capacity of the link between SN1 and DN1 has a low value.

Hereinafter, for convenience of description, it is assumed that the first target node 200 has generated an interference signal in the i-th time interval.

Subsequently, the first target node 200 does not receive the radio signal through the receiver 210 in the i + 1 th time interval, which is the next time interval of the i th time interval, and receives the interference signal through the transmitter 240. Broadcast

Thereafter, the first target node 200 repeatedly performs reception and non-reception of the radio signal through the receiver 210 from the i + 2 th time period. The first source node repeats the transmission and the non-transmission of the first signal so as to correspond to the reception and non-reception of the radio signal at the first target node 200. In other words, the link between the first source node and the first target node 200 is repeatedly turned on / off from the i + 2 th time period. For example, the first source node and the first target node 200 may transmit / receive radio signals in even-numbered time intervals and may not transmit / non-receive radio signals in odd-numbered time intervals.

On the other hand, the broadcast interference signal acts as interference at other destination nodes that receive radio signals from their source nodes in the i + 1th time interval, and thus communication capacity at other destination nodes is also changed.

For example, in the example of FIG. 3, when DN1 broadcasts an interference signal and SN1 does not transmit the first signal in the i + 1 th time interval as shown at the bottom of FIG. 3, another destination node. Since DN2 is located closer to DN1 than SN1, the amount of interference received by DN2 in the i + 1 th time interval is increased than in the i th time interval.

In addition, in the example of FIG. 4, if DN1 broadcasts the interference signal and SN1 does not transmit the first signal in the i + 1 th time interval as shown in the lower part of FIG. Since it is located closer to SN1 than DN1, the amount of interference received by DN2 in the i + 1 th time period is reduced than in the i th time period.

As such, when the communication capacity is changed in another destination node, the other destination node broadcasts the interference signal from the first destination node 200, which is a neighboring destination node, and the first source node and the first destination node 200. ) Repeats the transmission / reception and non-transmission / non-reception of the radio signal from the i + 2th time interval. Therefore, the other target node and its source node transmit and receive signals so as not to overlap with the signal transmission and reception between the first source node and the first target node 200 to minimize the reduction in communication capacity due to interference.

In other words, another target node adjacent to the first target node 200 includes a first signal transmitted from its source node and a second signal transmitted from one or more other nodes other than its source node in each time interval. A wireless signal is received and a communication capacity of a link with its source node is calculated using the reception strength of the first signal and the reception strength of the second signal in each time interval. In this case, the other target node has a communication capacity calculated in the i-th time interval (i-th communication capacity) and a communication capacity calculated in the i + a-th time interval (a is an integer of 1 or more) (i + a-th communication capacity). When the rate of change (increase or decrease) is greater than the preset rate of change in communication capacity, reception and non-reception of the radio signal may be repeated from the i + a + 1th time interval. The source node of the other target node may repeat the transmission / non-transmission of the first signal to correspond to the reception / non-reception of the radio signal of the other target node. Accordingly, the transmission and reception of signals between the first source node / first destination node 200 does not overlap with the transmission and reception of signals between other source nodes / other destination nodes.

As described above, according to an embodiment of the present invention, source nodes constituting the distributed network can transmit signals so that they do not overlap with each other even if they do not exchange scheduling information for signal transmission with each other, thereby reducing overall communication capacity. This has the advantage of minimizing interference on individual links without the need to do so.

Meanwhile, the operation of the first object node 200 described above may be performed in the same manner in other object nodes, and the operation of the other object nodes may be performed in the same manner in the first object node 200. Table 1 below summarizes the operation algorithm of the target node.

Meanwhile, according to another embodiment of the present invention, the first source node may transmit a signal to the first target node 200 in cooperation with one or more cooperative nodes. In other words, the at least one cooperating node receives the first signal from the first source node in the odd time interval, the first source node transmits the first signal to the first destination node 200 in the even time interval, One or more cooperating nodes may transmit the first signal received from the first source node to the first destination node. Hereinafter, the first signal transmitted by the cooperating node will be referred to as a "third signal".

)는 아래의 수학식 6과 같이 표현될 수 있다.
In this case, the received signal for a signal transmitted from one or more cooperating nodes (

) May be expressed as Equation 6 below.

는 제1 목적 노드(200)와 협력 노드 사이의

차원의 채널 매트릭스,

는

차원의 잡음 벡터,

는

차원의 간섭 신호에 대한 벡터이다. 이 때,

는 아래의 수학식 7과 같이 표현될 수 있다.
here,

Is between the first destination node 200 and the cooperating node.

Dimensional channel matrix,

The

Dimensional noise vector,

The

Vector of interfering interference signals. At this time,

May be expressed as Equation 7 below.

는 j번째 다른 노드와 제1 협력 노드 사이의

차원의 채널 매트릭스를 의미한다. here,

Is between the j th other node and the first cooperating node

The channel matrix of the dimension.

)는 아래의 수학식 8과 같이 표현될 수 있다.
Therefore, when the first source node and the one or more cooperating nodes cooperate to transmit the first signal and the third signal, the radio signal received through the receiver 210 (

) May be expressed as Equation 8 below.

은 링크 l에서의 협력 노드의 개수,

는 협력 노드에서 제3 신호를 전송하는데 소비된 전력,

는 협력 노드와 제1 목적 노드(200) 사이의

차원의 채널 매트릭스,

는 협력 노드에서의

차원의 가중치 매트릭스를 의미한다. 그리고,

는 아래의 수학식 9와 같이 표현되는 일반화 항을 의미한다.
here,

Is the number of cooperating nodes on link l ,

Is the power consumed to transmit the third signal at the cooperating node,

Is between the cooperative node and the first destination node 200.

Dimensional channel matrix,

At the cooperating node

The weight matrix of the dimension. And,

Denotes a generalization term expressed as in Equation 9 below.

이고,

이다. here,

ego,

to be.

In addition, when the first source node and the first cooperative node cooperate to transmit the first signal and the third signal to the first target node 200, the communication capacity calculator 220 further increases the reception strength of the third signal. Communication capacity can be calculated. In this case, the communication capacity may be proportional to the reception strength of the first signal and the reception strength of the third signal, and may be inversely proportional to the reception strength of the second signal.

In addition, when transmitting and receiving a signal using one or more cooperative nodes, the first source node is a weak transmission power in a time interval in which the first target node 200 does not receive a radio signal after the i + 2th time interval. The first source node and the at least one cooperating node cooperate with the first signal in a time interval in which the first target node 200 receives the radio signal after the i + 2 th time interval, and after the i + 2 th time interval. The signal and the third signal are transmitted to the first target node 200.

Hereinafter, an operation of transmitting the first signal and the third signal by cooperating with the first source node and the one or more cooperative nodes will be described in more detail with reference to FIG. 5.

1. Transmission power allocation for the first source node and one or more cooperating nodes

Assuming that one or more cooperating nodes transmit a third signal at the same transmit power, and assume that all nodes in the distributed network have one antenna, the wireless signal received at the first destination node 200 is It may be expressed as in Equation 10.

,

,

,

,

,

, ,

,

,

의 관계가 성립한다. Here, each parameter of Equation 10 is modified by the parameters related to the multiple antennas in Equations 1 to 9 into parameters for one antenna.

,

,

,

,

,

, ,

,

,

The relationship is established.

,

및

의 관계가 성립하는 것으로 가정하면, 제1 목적 노드(200)에서 수신된 무선 신호의 SINR은 아래의 수학식 11과 같이 표현될 수 있다.
To maximize signal gain,

,

And

If it is assumed that the relationship is true, the SINR of the radio signal received at the first target node 200 can be expressed as Equation 11 below.

이고,

이다. here,

ego,

to be.

가 상수

의 값을 가지면, 수신된 무선 신호의 SINR 값은 함수

로 정의될 수 있으며, SINR을 최대화하기 위한 최적화 문제는 아래의 수학식 12와 같이 표현될 수 있다.
if,

Is a constant

With a value of, the SINR value of the received radio signal is a function

The optimization problem for maximizing SINR may be expressed as Equation 12 below.

는 상수인 전송 전력 파워를 의미하며, 상기한 수학식 12의 최적화 문제에 대한 라그랑지안 함수(Lagrangian Function)는 아래의 수학식 13과 같이 표현될 수 있다.
here,

Denotes a constant transmit power power, and the Lagrangian function for the optimization problem of Equation 12 may be expressed as Equation 13 below.

와

의 Local Maximum 값을 찾기 위한

,

및

가 존재하며, 이는 아래의 수학식 14를 통해 산출될 수 있다.
According to the Krush-Kuhn-Tucker (KKT) condition,

Wow

To find the Local Maximum value of

,

And

Is present, which may be calculated through Equation 14 below.

및

는 아래의 수학식 15와 같이 표현될 수 있다.
here,

And

May be expressed as in Equation 15 below.

이고,

이다. here,

ego,

to be.

,

,

및

의 관계가 성립할 때 만족된다. KKT conditions

,

,

And

Is satisfied when the relationship is established.

및

는 도 5에 도시된 바와 같이 4가지 case로 분류될 수 있다. 보다 상세하게, 도 5의 상단은 협력 노드의 개수가 하나인 경우의 전송 전력 할당 영역을 도시하고 있고, 도 5의 하단은 협력 노드의 개수가 2 이상인 경우의 전송 전력 할당 영역을 도시하고 있다. 각 case에 대해 보다 상세하게 설명하면 아래와 같다. Is the optimal transmit power of the first source node and one or more

And

5 may be classified into four cases as shown in FIG. 5. More specifically, the upper part of FIG. 5 shows a transmission power allocation area when the number of cooperative nodes is one, and the lower part of FIG. 5 shows a transmission power allocation area when the number of cooperative nodes is two or more. Each case is described in more detail below.

이므로, 아래의 수학식 16과 같은 관계가 성립한다.
First, in case 1

Therefore, the relationship as shown in Equation 16 below is established.

이면, 최적의 전송 전력은 각각

및

로 설정된다. therefore,

If the optimal transmission power

And

.

이므로, 아래의 수학식 17과 같은 관계가 성립한다.
Next, in case 2,

Therefore, the relationship as shown in Equation 17 below is established.

이면, 최적의 전송 전력은 각각

및

로 설정된다. therefore,

If the optimal transmission power

And

.

이고,

이면,

이고

일 때 KKT 조건이 만족된다. 따라서,

의 관계가 성립하고, 최적의 전송 전력을 산출하기 위한 수식은 아래의 수학식 18과 같이 표현된다.
Go ahead, in case 3,

ego,

If so,

ego

When KKT condition is satisfied. therefore,

Is established, and an equation for calculating an optimal transmission power is expressed by Equation 18 below.

를 아래의 수학식 19와 같이 정의한다.
In this case, in order to find an approximation solution to the above equation (18), the function

Is defined as in Equation 19 below.

가 0에 가깝다면, 가 최적 전송 전력 값인

에 근접하게 된다. 반면에,

가 큰 양수 또는 큰 음수의 값을 가진다면,

는

에서 멀어지게 된다. if,

If is close to 0, is the optimal transmit power value.

Close to. On the other hand,

Is a large positive or large negative value,

The

Away from

는

와

에 위치한다. 즉,

는 case 1과 case 2 사이에 존재한다. And, referring to the top of Figure 5,

The

Wow

Located in In other words,

Is between case 1 and case 2.

이면

는 case 1의 최적값인

에서는 가까이 위치하고, case 2의 최적값인

에서는 멀리 위치한다. 이는 case 1과 case 2 각각의 최적값은 서로 반대쪽 끝에 위치하기 때문이다. At this time,

If

Is the optimal value for case 1

Is close to, and the optimal value for case 2

Is far away. This is because the optimal values for case 1 and case 2 are on opposite ends of each other.

이면,

는 case 1의 최적값인

와 가까워지고,

이면,

는 case 2의 최적값인

와는 가까워지나

와는 멀어진다. therefore,

If so,

Is the optimal value for case 1

Getting closer to

If so,

Is the optimal value for case 2

Are you getting closer?

Away from you.

Therefore, the function for optimal transmission power allocation may be configured as shown in Equation 20 below.

는

의 추정값이고(0 이상

이하의 값을 가짐),

은 상수이며,

이고,

이며,

이고,

이다. here,

The

Is an estimate of (zero or greater)

Has the following values),

Is a constant,

ego,

Is,

ego,

to be.

는

이 0에 가까워질수록, 그리고

가 감소할수록 증가한다. 또한, 추정된 전송 전력

는

가 0에 가까울수록 감소한다. Estimated transmit power

The

Is closer to zero, and

Increases with decreasing. In addition, the estimated transmit power

The

Decreases as 0 approaches zero.

일 때,

가

로 결정되면,

는

를 만족하지만

를 만족하지는 못한다. 따라서,

일 경우 전송 전력 할당값을 조정할 필요가 있다. Also,

when,

end

Once determined,

The

But satisfy

It is not satisfied. therefore,

In this case, it is necessary to adjust the transmission power allocation value.

는

를 이용하여

로 설정된다. Considering the above limitations of the transmission power setting

The

Using

.

로 인해,

는

일 때,

가 되지 못한다. 따라서, 이 경우

의 제약이 성립한다. And, the constraint of the transmission power setting

Due to,

The

when,

Cannot be. Therefore, in this case

The constraint of is established.

는

로 제약되며, 전송 전력 설정 제한인

로 인해,

일 때,

는

가 되지 못한다. 따라서, 이 경우,

가 된다. Likewise,

The

Is limited to the transmit power setting

Due to,

when,

The

Cannot be. So in this case,

.

이고,

이면,

이고

이다. 이 때,

는 영역

와

사이에 위치한다. 즉, 최적값

는 case 1에서의 최적값과

사이에 위치한다. Finally, in case 4,

ego,

If so,

ego

to be. At this time,

Area

Wow

Located in between. That is, the optimal value

Is the optimal value in case 1

Located in between.

이면,

는 case 1의 최적값인

에 가까이 위치하고,

에서는 멀리 떨어져 위치한다. 왜냐하면, case 1의 최적점과

는 서로 반대편에 위치하기 때문이다. therefore,

If so,

Is the optimal value for case 1

Located close to

In the far away place. Because the optimal point of case 1

Is located on opposite sides of each other.

이면,

는 case 1의 최적값인

에서는 가까이 위치한다. 반면에

이라면,

는

에 가까이 위치하지만

에서는 멀리 떨어져 위치한다. therefore,

If so,

Is the optimal value for case 1

Is located close by. On the other hand

If

The

But close to

In the far away place.

이라면,

는 무한대 값으로 발산한다. 그러므로,

(

는 매우 작은 상수 값을 의미함)와

로 대체한다.

및

를 각각

및

로 다시 정의하면,

및

의 관계가 성립한다. 그리고, 상기에서 설명한 바와 같이

를 얻기 위해 함수를 사용하며,

를 이용하여

를 산출한다. Also,

If

Radiates to infinity. therefore,

(

Means very small constant values)

Replace with

And

Each

And

Redefine by

And

The relationship is established. And, as described above

Use a function to get

Using

Calculate

Table 2 below summarizes the operation algorithm of the optimal power transfer allocation scheme described above.

2. Beamforming Techniques for the First Source Node and One or More Cooperative Nodes

When each of the first source node and the one or more power nodes includes a plurality of antennas, the wireless signal received by the first target node 200 may be expressed by Equation 21 below.

를 특이값 분해하면, 하나의 특이값이 매우 큰 값을 가지면, 제1 소스 노드와 제1 목적 노드(200) 사이의 통신 용량이 매우 큰 값을 가질 수 있게 된다. The first source node transmits one symbol using a weight vector. therefore,

When singular value decomposition is performed, if one singular value has a very large value, the communication capacity between the first source node and the first target node 200 may have a very large value.

와

의 m번째 행 벡터를 이용하여 가중치 매트릭스를 구성한다. 이를 통해,

의 m번째 특이값이 매우 큰 값을 가지게 된다. therefore,

Wow

A weight matrix is constructed using the m th row vector of. because of this,

The mth singular value of is very large.

이고,

이며,

과

을

와

의 m번째 행 벡터 및 열 벡터라고 하면,

는

로 구성된다. 여기서,

와

의 행 벡터 및 열 벡터는 서로 독립적이므로,

이고,

(

)의 관계가 성립한다. More specifically,

ego,

Is,

and

of

Wow

Let's say the mth row vector and column vector of

The

It consists of. here,

Wow

Since the row and column vectors of are independent of each other,

ego,

(

) Relationship holds.

를

와

의 m번째 행 벡터 및 열 벡터로 구성하면, m번째 대각 성분(diagonal) 값은 아래의 수학식 22와 같이 표현된다.
therefore,

To

Wow

When the m-th row vector and the column vector are configured, the m-th diagonal component value is expressed by Equation 22 below.

와

를 고려하여

를 아래의 수학식 23과 같이 정의한다.
And,

Wow

Considering

Is defined as in Equation 23 below.

가 되며, 제1 목적 노드(200)에서 수신된 무선 신호는 아래의 수학식 24와 같이 다시 표현될 수 있다.
Also, the associated weight vector

In this case, the wireless signal received by the first target node 200 may be represented again as in Equation 24 below.

,

및

를 얻기 위해

에 대해 특이값 분해를 수행한다. 여기서,

와

는 유니터리 매트릭스(unitary matrix)이고,

는

의 대각 매트릭스(diagonal matrix)이다. And

,

And

To get

Perform singular value decomposition for. here,

Wow

Is the unitary matrix,

The

Is the diagonal matrix of.

와

를

의 가장 큰 특이값과 대응되는

와

의 열 벡터라 하면,

는

차원의 벡터이므로,

와 같이 2개의

차원의 벡터로 분리한다. 신호 합의 전력을 최대화하기 위하여 협력 노드로 제1 신호를 전송할 때에는

을 사용하고 제1 목적 노드(200)로 신호를 전송할 때는

를 사용한다.

Wow

To

Corresponds to the largest singular value of

Wow

Suppose you have a column vector of

The

Since it is a vector of dimensions,

As 2

Separate into dimension vectors. When transmitting the first signal to the cooperating node to maximize the signal sum power

And transmit a signal to the first destination node 200

Lt; / RTI >

라 하면,

이고,

로 설정된다. To maximize communication capacity

Say,

ego,

.

Therefore, the SINR for the radio signal received at the first target node 200 may be expressed as Equation 25 below.

는 수신 가중치 벡터이고,

이며.

이다. here

Is the received weight vector,

And

to be.

는

와

로 표현되며, 그리고

,

및

의 함수가 된다. As explained above

The

Wow

Expressed as, and

,

And

Becomes a function of.

와

를 구하기 위해서는 제1 소스 노드의 가중치 벡터와 제1 목적 노드(200)의 수신 가중치 벡터를 알아야 하고, 이는 반복 알고리즘(iterative algorithm)을 통해 산출될 수 있다.

Wow

In order to obtain, it is necessary to know the weight vector of the first source node and the received weight vector of the first target node 200, which can be calculated through an iterative algorithm.

및

에 대해

의 함수로 표현될 수 있으므로, 최적화 문제는

를 최대화하는 문제로 정리될 수 있다. 이 때,

및

는 아래의 수학식 26과 같이 표현될 수 있다.
And SINR is given

And

About

Can be expressed as a function of, so the optimization problem is

Can be solved to maximize the problem. At this time,

And

May be expressed as Equation 26 below.

이다. here,

to be.

,

,

,

및

를 동시에 결정하여야 하며, 이는 아래의 표 3과 같은 알고리즘을 통해 수행될 수 있다. To find the optimal value

,

,

,

And

It should be determined at the same time, this can be performed through the algorithm shown in Table 3 below.

,

,

,

,

,

및

는 반복 알고리즘을 진행하는 동안 산출되는

,

,

,

,

,

및

의 추정 값이다. In Table 3 above,

,

,

,

,

,

And

Is computed during the iterative algorithm

,

,

,

,

,

And

Is an estimated value.

를 구성하기 위해서는

에 대한 함수인

를 산출하여야 하며,

는

로부터 시작하여 추정된다. 이 때,

를 추정하기 위해,

를 사용하고,

및

와 같이 초기화를 수행한 후,

회 동안 반복 알고리즘을 수행한다.

In order to construct

Function for

To be calculated,

The

Is estimated starting from At this time,

To estimate

Using,

And

After initialization,

Perform an iterative algorithm for times.

,

및

를 이용하여

를 산출하며,

를 위해

를 특이값 분해한다. 여기서,

와

는 유니터리 매트릭스이고,

는

의 특이값을 원소로 가지는 대각 매트릭스이다. 그리고,

와

는

의 가장 큰 특이값과 대응되는 열 벡터이다. 또한,

과 같이

를

로 정의하면(

및

는

차원의 벡터임),

,

,

로 정의된다. 그리고,

는

를 이용하여 갱신된다. first,

,

And

Using

Yields,

for

Decompose the singular values. here,

Wow

Is the unitary matrix,

The

Diagonal matrix with singular values of as element. And,

Wow

The

Is the column vector corresponding to the largest singular value of. Also,

As

To

If defined as (

And

The

Is a vector of dimensions),

,

,

. And,

The

Is updated using.

는

,

,

및

를 이용하여 산출된다. 이에 따라,

가 산출된다. 그리고, 최초 전송 전력 값을

및

로 설정한다. In each iteration step, SINR

The

,

,

And

It is calculated using Accordingly,

Is calculated. And, the initial transmit power value

And

.

이기 때문에,

이면, KKT 조건은 최초의 전송 전력 값을 유지시키며

,

만을 갱신하다. 반대로,

이면, KKT조건에 위배되며 최초의 전송 전력 값은 최적의 전송 전력 값이 아니게 되고, 반복을 통해 전송 전력 값을 낮추어야 한다. 따라서,

,

로 전송 전력 값이 갱신된다(

는 특정 상수 값으로서,

의 값을 가진다). At this time,

Because

, The KKT condition maintains the original transmit power value

,

Renew bay Contrary,

In this case, the KKT condition is violated and the initial transmission power value is not the optimal transmission power value, and the transmission power value should be lowered through repetition. therefore,

,

The transmit power value is updated to

Is a specific constant value,

Has the value of).

를 최대화하는

를 산출하며, 최적의 전송 전력 값들과 송수신 가중치 벡터를

,

,

,

및

를 이용하여 산출한다.
Finally, SINR after iteration

To maximize

And the optimal transmit power values and the transmit / receive weight vector

,

,

,

And

Calculate using

6 is a flowchart illustrating the overall flow of a method for controlling signal reception of a node constituting a distributed network according to an embodiment of the present invention. Hereinafter, a process performed in each step will be described.

First, in step S610, the node receives a radio signal including a first signal transmitted from a source node of the node and a second signal transmitted from one or more other nodes other than a source node in a distributed network in an i-th time interval. . In operation S620, the node calculates the communication capacity of the link between the node and the source node using the reception strength of the first signal and the reception strength of the second signal.

According to an embodiment of the present invention, the communication capacity may be proportional to the reception strength of the first signal and inversely proportional to the reception strength of the second signal.

Subsequently, in step S630, the node generates an interference signal when the calculated communication capacity is smaller than the preset threshold communication capacity, and in step S640, the node does not receive the radio signal in the i + 1th time interval. Broadcasts an interfering signal.

Finally, in step S650, the node repeatedly performs reception and non-reception of the radio signal from the i + 2 th time period. At this time, the source node repeats the transmission and the non-transmission of the first signal so as to correspond to the reception and non-reception of the wireless signal of the node from the i + 2th time interval.

Meanwhile, the source node may transmit signals to the node in cooperation with one or more cooperating nodes.

In this case, in step S610, the node further receives a third signal transmitted from one or more cooperating nodes in the i-th time interval, and in step S620, the node further uses the received signal strength of the third signal to increase its communication capacity. Can be calculated. In this case, the communication capacity may be proportional to the reception strength of the first signal and the reception strength of the third signal, and may be inversely proportional to the reception strength of the second signal.

The source node transmits the first signal to one or more cooperating nodes in a time interval in which the node does not receive the radio signal after the i + 2th time period, and the node receives the radio signal after the i + 2th time period. In the time interval, the source node and the one or more cooperating nodes may transmit the first signal and the third signal to the node.

7 is a flowchart illustrating the overall flow of a method for controlling signal reception of a node constituting a distributed network according to another embodiment of the present invention. Hereinafter, a process performed in each step will be described.

First, in step S710, a node receives a radio signal including a first signal transmitted from a source node of a node and a second signal transmitted from one or more other nodes other than a source node in a distributed network in an i-th time interval. . In operation S720, the node uses the reception strength of the first signal and the reception strength of the second signal received in the i-th time interval, and the communication capacity of the link between the node and the source node in the i-th time period (i-th). Communication capacity).

Subsequently, in step S730, the node receives the radio signal in the i + a th time interval, and in step S740, the node receives the received strength and the second signal of the first signal received in the i + a th time period. Using the reception strength, the communication capacity of the link between the node and the source node in the i + ath time interval (i + ath communication capacity) is calculated.

According to an embodiment of the present invention, the i th communication capacity and the i + a th communication capacity may be proportional to the reception strength of the first signal and inversely proportional to the reception strength of the second signal.

Finally, in step S750, when the change rate between the i th communication capacity and the i + a th communication capacity is greater than the preset communication capacity change rate, the node receives and receives no radio signals from the i + a + 1 th time interval. Repeat by At this time, the source node repeats the transmission and the non-transmission of the first signal so as to correspond to the reception and non-reception of the radio signal of the node from the i + a + 1th time interval.

Meanwhile, as described above, the source node may transmit a signal to the node in cooperation with one or more cooperative nodes.

In this case, steps S710 and S730 further receive a third signal transmitted from one or more cooperating nodes, and steps S720 and S740 further use the i th signal using the reception strength of the third signal. The communication capacity and the i + a th communication capacity can be calculated. In this case, the i th communication capacity and the i + a th communication capacity may be proportional to the reception strength of the first signal and the reception strength of the third signal, and may be inversely proportional to the reception strength of the second signal.

The source node transmits the first signal to one or more cooperating nodes in a time interval in which the node does not receive a radio signal after the i + a + 1th time interval, and the node after the i + a + 1th time interval. The source node and the one or more cooperating nodes may transmit the first signal and the third signal to the node in a time interval for which the signal is not received.

So far, embodiments of the method for controlling signal reception of a node according to the present invention have been described, and the configuration of the node 200 described above with reference to FIG. 2 is also applicable to the present embodiment. Hereinafter, a detailed description will be omitted.

In addition, embodiments of the present invention may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Examples of program instructions, such as magneto-optical and ROM, RAM, flash memory and the like, can be executed by a computer using an interpreter or the like, as well as machine code, Includes a high-level language code. The hardware device described above may be configured to operate as one or more software modules to perform the operations of one embodiment of the present invention, and vice versa.

As described above, the present invention has been described with reference to particular embodiments, such as specific elements, and limited embodiments and drawings. However, it should be understood that the present invention is not limited to the above- Various modifications and variations 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 (12)

In the signal reception control method of a node constituting a distributed network,
Receive a wireless signal that includes a first signal transmitted from a source node of the node and a second signal transmitted from one or more other nodes in the distributed network during the i th time interval (i is an integer of 1 or more). Making;
Calculating a communication capacity of a link between the node and the source node using the reception strength of the first signal and the reception strength of the second signal;
Generating an interference signal when the communication capacity is less than a preset threshold communication capacity;
broadcasting the interference signal without receiving the wireless signal in an i + 1th time interval; And
repeating reception and non-reception of the radio signal from an i + 2 th time period
Signal reception control method of a node comprising a. The method of claim 1,
And the communication capacity is proportional to the reception strength of the first signal and inversely proportional to the reception strength of the second signal. The method of claim 1,
And the source node repeats transmission and non-transmission of the first signal so as to correspond to reception and non-reception of the radio signal of the node from the i + 2th time interval. The method of claim 1,
Receiving the radio signal further receives a third signal transmitted from one or more cooperating nodes of the source node in the i-th time interval,
The calculating of the communication capacity may further include calculating the communication capacity by further using the reception strength of the third signal.
And the communication capacity is proportional to the reception strength of the first signal and the reception strength of the third signal, and inversely proportional to the reception strength of the second signal. 5. The method of claim 4,
The source node transmits the first signal to the at least one cooperating node in a time interval in which the node does not receive the radio signal after the i + 2th time interval,
The source node and the at least one cooperating node transmits the first signal and the third signal to the node in a time interval in which the node does not receive the radio signal after the i + 2th time interval. Method of controlling signal reception of a node. In the signal reception control method of a node constituting a distributed network,
Receive a wireless signal that includes a first signal transmitted from a source node of the node and a second signal transmitted from one or more other nodes in the distributed network during the i th time interval (i is an integer of 1 or more). Making;
The communication capacity of the link between the node and the source node in the i-th time interval by using the reception strength of the first signal and the reception strength of the second signal received in the i-th time interval (i-th communication capacity) Calculating;
receiving the wireless signal in an i + ath time interval (a is an integer of 1 or more);
The communication capacity of the link between the node and the source node in the i + a-th time interval by using the reception strength of the first signal and the reception strength of the second signal received in the i + a-th time interval (i calculating a + a th communication capacity; And
If the rate of change between the i th communication capacity and the i + a th communication capacity is greater than a preset communication capacity change rate, repeating reception and non-reception of the radio signal from an i + a + 1 th time period;
Signal reception control method of a node comprising a. The method according to claim 6,
And the i th communication capacity and the i + a th communication capacity are proportional to the reception strength of the first signal and inversely proportional to the reception strength of the second signal. The method of claim 7, wherein
And the source node repeats transmission and non-transmission of the first signal so as to correspond to reception and non-reception of the radio signal of the node from the i + a + 1th time interval. . The method of claim 7, wherein
Receiving the wireless signal in the i-th time interval and receiving the wireless signal in the i + a-th time interval further receive a third signal transmitted from one or more cooperating nodes of the source node,
The calculating of the i-th communication capacity and the calculating of the i + a-th communication capacity further include calculating the i-th communication capacity and the i + a-th communication capacity by further using the reception strength of the third signal.
The i th communication capacity and the i + a th communication capacity are proportional to the reception strength of the first signal and the reception strength of the third signal, and inversely proportional to the reception strength of the second signal. Receive control method. 10. The method of claim 9,
The source node transmits the first signal to the at least one cooperative node in a time interval in which the node does not receive the radio signal after the i + a + 1th time interval.
The source node and the one or more cooperating nodes transmit the first signal and the third signal to the node in a time interval in which the node does not receive the radio signal after the i + a + 1th time interval. A signal reception control method of a node. A computer-readable recording medium having recorded thereon a program for performing the method of any one of claims 1 to 10. In a node constituting a distributed network,
Receive a wireless signal that includes a first signal transmitted from a source node of the node and a second signal transmitted from one or more other nodes in the distributed network during the i th time interval (i is an integer of 1 or more). A receiving unit;
A communication capacity calculator configured to calculate a communication capacity of a link between the node and the source node by using the reception strength of the first signal and the reception strength of the second signal;
An interference signal generator for generating an interference signal when the communication capacity is smaller than a preset threshold communication capacity; And
Transmitter for broadcasting the interference signal in the i + 1 th time interval
Including,
And the receiving unit does not receive the wireless signal in the i + 1th time interval, and repeats reception and non-reception of the wireless signal from the i + 2th time interval.

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