KR101489883B1 - Apparatus and method for transferring using multi relay - Google Patents

Abstract

A multiple-relay transmission apparatus according to the present invention comprises: multiple source nodes which alternately and repeatedly perform a first phase, where preceding data is transmitted during a first transmission period corresponding to a unit frame transmission period, and a second phase, where following data subsequent to the preceding data is transmitted during a second transmission period subsequent to the first transmission period; multiple relay nodes including a first group of relay nodes, which receive the preceding data from the source nodes during the first phase and transmit the received preceding data during the second phase, and a second group of relay nodes, which receive the following data from the source nodes during the second phase and transmit the received following data during the first phase; and multiple destination nodes which receive the following data transmitted by the second group of relay nodes during the first phase and receive the preceding data transmitted by the first group of relay nodes during the second phase. The relay nodes remove an interference signal from the other group of relay nodes based on an interference removing filter, when the preceding data or the following data are received from the source nodes, and prevent the data from serving as the interference signal for the other group of relay nodes based on the interference removing filter, when the preceding data or the following data are transmitted to the destination nodes.

Description

[0001] DESCRIPTION [0002] APPARATUS AND METHOD FOR TRANSFERRING USING MULTI RELAY [0003]

The present invention relates to a multi-relay transmission apparatus and method, and more particularly, to a multi-relay transmission apparatus and method capable of increasing network freedom while using a half-duplex relay in an interference relay network.

A relay is used in a wireless communication system to resolve a communication disconnection between a base station and a terminal. In general, because relays use half-duplex relaying, the efficiency of the frequency is reduced by half and the degree of freedom of the transmission rate is reduced by half.

In an interference relay network including a relay, a conventional communication method carries a signal through two steps. First, in the first step, each source sends a signal to a relay in the network. In the second step, the signals received by the relay are transmitted back to the destination node. As each source transmits signals to a plurality of relays, inter-source interference (ISI) exists from other sources in the network.

The existing method utilizes the interference sorting technique announced in the recent research to remove such interference signal. The existing method increases the degree of freedom of the effective channel from the source through the relay to the destination node by using the relay higher than the degree of freedom in the existing effective channel without using the interference sorting technique, Effect can be obtained.

However, the prior art still involves the problem of reduced network freedom due to half duplex relay communication. That is, since the signal transmitted from each source is transmitted to the destination node through the relay, the transmission rate is reduced to half compared with the direct communication between the source and the destination node. The conventional interference-based transmission method will be described with reference to FIGS. 1 and 2. FIG.

1 is a diagram illustrating an interference-based transmission method in an interference relay network environment according to the related art.

1 is a diagram illustrating a case where there are M transmission / reception node pairs and N relay nodes. In the transmission scheme of FIG. 1, each transmitting terminal transmits a signal to a relay node in a first phase, and a signal is transmitted from a relay node to each receiving terminal in a second phase. However, such a scheme has a problem that the degree of freedom of the total data rate is reduced due to the use of a half-duplex relay node.

FIG. 2 is a diagram illustrating an interference-based sequential transmission method according to the prior art.

2 illustrates a sequential transmission scheme in a relay environment having a pair of transmission / reception nodes and three decode-and-forward relay nodes. When using the sequential transmission scheme, it is possible for the transmitting end to transmit signals continuously to the relay node. At this time, the inter-relay interference signal can be removed through the interference filter based relay filter design. However, such a technique has a problem that it can be applied to only one transmission / reception node pair and three relay node environments. In addition, although the conventional sequential transmission scheme applies the transmission scheme after decoding, when the amplification-and-forward scheme is applied, not only a signal to be transmitted but also an inter-relay interference signal is amplified There is a problem that it is transmitted.

In this regard, Korean Patent Laid-Open Publication No. 2013-0056086 (entitled " Multiple Relay Transmission Device and Method Using Interference Alignment Technique ") minimizes the degree of freedom in interference cancellation by using an interference alignment technique, Discloses a technique capable of achieving a higher data rate than a relay transmission method.

In addition, Korean Patent Laid-Open Publication No. 2011-0019183 (a half-duplex relay system, a cooperative communication method and a signal processing method in a receiver in this case), one of the relay nodes operates as a receiving node for each time slot, The relay node discloses a technique of operating as a transmission node.

However, the above prior art can be applied to only one transmission / reception pair and three relay node environments, and is not applicable to an environment having a plurality of transmission / reception node pairs and a plurality of relay nodes. Therefore, it is necessary to design a relay filter capable of removing inter-relay interference signals without limitation on the number of transmission / reception node pairs and relay nodes, and transferring only a desired signal from a source to a destination node.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide an apparatus and a method for controlling an interference that includes a plurality of source nodes, a plurality of relay nodes divided into a first group and a second group, A relay network system comprising: a relay node for transmitting and receiving data alternately in two stages of a first phase and a second phase; and a multiplexing and demultiplexing device for removing interference signals using an interference elimination filter and an interference alignment filter at a relay node, A relay transmission apparatus and method are provided.

As a technical means for accomplishing the above technical object, a multi-relay transmission apparatus of the present invention includes a first phase for transmitting preceding data at a first transmission time corresponding to a unit frame transmission time, A second phase for alternately repeating the second phase of transmitting the preceding data subsequent to the preceding data at a second transmission time, the first data being received from the source node in the first phase, A first group relay node for transmitting the received preceding data and a second group relay node for receiving the following data from the source node in the second phase and transmitting the received uplink data in the first phase And in the first phase, the second group relay node transmits And a plurality of destination nodes receiving the trailing data and receiving the preceding data transmitted by the first group relay node in the second phase, wherein the plurality of relay nodes transmit the preceding data from the plurality of source nodes Wherein the interference cancellation filter removes interference signals from other group relay nodes based on the interference cancellation filter when receiving the data or the trailing data, and when transmitting the preceding data or the following data to the plurality of destination nodes, So that the data does not act as an interference signal to the other group relay node.

According to a second aspect of the present invention, there is provided a method for transmitting a multi-relay according to the present invention, wherein a source node transmits a preceding data to a first group relay node at a first transmission time corresponding to a unit frame transmission time, Performing a first phase in which the second group relay node receiving the preceding data and receiving previous data of the preceding data from the source node transmits the previous data to a plurality of destination nodes, The second group relay node transmits the following data at the source node to the second group relay node at the second transmission time, and the first group relay node receives the next data at the second transmission time, And a second phase performing step of transmitting the received preceding data to the plurality of destination nodes, The first group relay node and the second group relay node remove the interference signal from the other group relay node based on the interference cancellation filter when receiving the preceding data or the following data from the plurality of source nodes, So that the data does not act as an interference signal to the other group relay node based on the interference sorting filter when transmitting the preceding data or the following data to the plurality of destination nodes.

According to the above-described object of the present invention, when a plurality of sources in a network transmit signals to a final destination node designated by each of a plurality of relays, the source continuously transmits signals, .

In addition, the present invention is applicable to both the number of source node destination node pairs and the general situation where the number of relay nodes is not limited.

1 is a diagram illustrating an interference-based transmission method in an interference relay network environment according to the related art.
FIG. 2 is a diagram illustrating an interference-based sequential transmission method according to the prior art.
3 is a diagram illustrating a multi-relay transmission apparatus according to a first embodiment of the present invention.
4 is a diagram showing a first phase state in a multi-relay transmission apparatus.
5 is a diagram showing a second phase state in a multi-relay transmission apparatus.
6 is a diagram illustrating a multi-relay transmission method according to a second embodiment of the present invention.
FIG. 7 is a diagram illustrating a multi-relay transmission method according to a third embodiment of the present invention.
8 is a graph comparing degrees of freedom of the present invention with those of the prior art.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "electrically connected" with another part in between . Also, when an element is referred to as "comprising ", it means that it can include other elements as well, without departing from the other elements unless specifically stated otherwise. The word " step (or step) "or" step "used to the extent that it is used throughout the specification does not mean" step for.

3 is a diagram illustrating a multi-relay transmission apparatus according to a first embodiment of the present invention.

The relay relay apparatus according to the present invention includes a plurality of source nodes 100, a plurality of relay nodes 200, and a plurality of destination nodes 300. At this time, each of the source node 100, the relay node 200, and the destination node 300 has an arbitrary number of antennas.

3 refers to a hardware component such as software or an FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit), and performs predetermined roles .

However, 'components' are not meant to be limited to software or hardware, and each component may be configured to reside on an addressable storage medium and configured to play one or more processors.

Thus, by way of example, an element may comprise components such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, Routines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables.

The components and functions provided within those components may be combined into a smaller number of components or further separated into additional components.

The plurality of source nodes 100 perform a first phase of transmitting the preceding data at a first transmission time corresponding to a unit frame transmission time, and perform a first phase at a second transmission time subsequent to the first transmission time, And the second phase of transmitting data is alternately repeated. That is, the plurality of source nodes 100 transmit the preceding data to the first group relay node 210 to be described below in the first phase, and send the following data to the second group relay node 230 in the second phase do. Each source node 100 of the multiple relay transmission apparatus according to the present invention can not directly communicate with each destination node 300 and can transmit signals between a plurality of source nodes 100 and a plurality of destination nodes 300 And performs communication through a plurality of relay nodes 200 to relay.

The plurality of relay nodes 200 are divided into a first group relay node 210 and a second group relay node 230. The first group relay node 210 receives the preceding data from the source node 100 in the first phase and transmits the preceding data received in the second phase to the plurality of destination nodes 300. The second group relay node 230 receives the trailing data from the source node 100 in the second phase and transmits the trailing data received in the first phase to the plurality of destination nodes 300.

The plurality of relay nodes 200 may be divided into a first group relay node 210 and a second group relay node 230. The classification into two groups is performed by the source node 100 . To this end, a plurality of relay nodes 200 include channel state estimators 211 and 231, a plurality of source nodes 100 include a relay node selector 110 and a relay node changer 120 have.

The channel state estimators 211 and 231 included in the plurality of relay nodes 200 calculate a channel state estimation value based on the reference signal for channel estimation received from the plurality of source nodes 100, To the source node (100).

The relay node selector 110 included in the plurality of source nodes 100 receives a corresponding relay node exceeding a predetermined channel state threshold value among the channel state estimation values transmitted from the plurality of relay nodes 200, The relay node 210 or the second group relay node 230 can be selected.

In addition, the relay node change unit 120 may change the relay nodes other than the selected relay node among the plurality of relay nodes 200 to other relay nodes.

The process of determining the first group relay node 210 and the second group relay node 230 by the channel state estimators 211 and 231, the relay node selector 110 and the relay node changer 120 The following is a detailed description.

First, a plurality of source nodes 100 transmits a reference signal for channel estimation to all the relay nodes 200. Each relay node 200 calculates and feeds back a value obtained by estimating a channel state based on a reference signal received from the entire source node 100. Each of the source nodes 100 selects a relay node in the first group as a relay node 210 that exceeds a channel state threshold value set by the network based on the feedback channel result value information. Based on the selected relay node, the source node 100 determines the channel coefficient to be used by the relay nodes, and transmits the determined relay information and the channel coefficient value to each relay node.

At this time, the relay nodes that are not selected as the first group relay node 210 become the second group relay node 230 that receives a signal from the source nodes 100 again in the next step. In the first phase, even if the first group relay node 210 and the second group relay node 230 are classified, in the second phase, the source node 100 is connected to the second group relay node 230 In order to transfer data, the second group relay node 230 is selected based on the above-described method. In this case, even in the case of the relay node selected as the first group relay node 210 in the first phase, it can be selected as the second group relay node 230 in the second phase. That is, the roles of the first group relay node 210 to the second group relay node 230 may be changed. As described above, the multi-relay transmission apparatus according to the present invention can select a relay node group to be relayed when data is transmitted flexibly based on the channel state estimation value received from the relay nodes by the source node 100.

The relay nodes determined in this manner determine interference cancellation filters that can remove the interference signals sent by the relay nodes of the other groups through the relay filter generators 213 and 233 included in each relay node, And determines the relay filter.

The plurality of destination nodes 300 receive the trailing data transmitted by the second group relay node 230 in the first phase and the preceding data transmitted by the first group relay node 210 in the second phase. At this time, the plurality of destination nodes 300 can remove the interference signal from the relay node and the interference signal from the source node based on the received interference cancellation filter.

On the other hand, the plurality of source nodes 100 can transmit the precoded preceding data and the trailing data to the plurality of relay nodes 200 based on the precoding filter.

In addition, when a plurality of relay nodes 200 receive the preceding data or the following data from the plurality of source nodes 100, the relay nodes 200, The interference signal of the node is removed. That is, in the first phase, the first group relay node 210 receives the preceding data from the plurality of source nodes 100, and the second group relay node 230 receives the following data to the plurality of destination nodes 300 At this time, the first group relay node 210 may act as an interfering signal when a preceding data signal transmitted by the second group relay node 230 is received. Accordingly, the first group relay node 210 removes the interference signal generated by the second group relay node 230 using the interference cancellation filter.

In contrast, in the second phase, the second group relay node 230 receives the trailing data from the plurality of source nodes 100, and the first group relay node 210 transmits the preceding data to the plurality of destination nodes 300 At this time, the second group relay node 230 may act as an interference signal in the preceding data transmitted by the first group relay node 210 when receiving the following data. Accordingly, the second group relay node 230 removes the interference signal generated by the first group relay node 210 using the interference cancellation filter.

In addition, when a plurality of relay nodes 200 transmit the preceding data or the following data to the plurality of destination nodes 300, data is transmitted to the other group relay 300 based on the interference sorting filter generated through the relay filter generating units 213 and 233, Thereby preventing the node from acting as an interference signal. That is, the first group relay node 210 transmits the preceding data to the plurality of destination nodes 300 in the second phase, and the second group relay node 230 receives the following data from the plurality of source nodes 100 At this time, the trailing data received by the second group relay node 230 may act as an interference signal when the first group relay node 210 transmits the preceding data to the plurality of destination nodes 300. Accordingly, the first group relay node 210 aligns each signal using an interference alignment filter to prevent this.

In contrast, the second group relay node 230 transmits the trailing data to the plurality of destination nodes 300 in the first phase, and the first group relay node 210 receives the preceding data from the plurality of source nodes 100 At this time, the preceding data received by the first group relay node 210 may act as an interference signal when the second group relay node 230 transmits the following data to the plurality of destination nodes 300. Thus, the second group relay node 230 aligns each signal using an interference alignment filter.

Hereinafter, a signal transfer formula applied at the time of data transmission from the source node 100 to the destination node 300 through the first group relay node 210 and the second group relay node 230 will be described.

, 서로 다른 그룹에 속한 릴레이 노드 간 채널을

, 릴레이 노드에서 목적지 노드 사이의 채널을

라고 한다. 이때, 위 첨자 X는 각 순차적 전송 단계에 따라 제 1 그룹 또는 제 2 그룹을 나타내며, 각 채널의 아래 첨자 ij는 j 번째 송신 노드로부터 I 번째 수신 노드로의 채널을 의미한다. 또한, 각 소스에서 전송되는 프리코딩 필터, 릴레이 필터, 목적지 노드에서의 간섭 제거 필터는 각각

,

,

와 같은 행렬의 형태로 나타낼 수 있다.First, the channel between the relay node and the source node

, Channels between relay nodes belonging to different groups

, The channel between the relay node and the destination node

. In this case, the superscript X represents the first group or the second group according to each sequential transmission step, and the subscript ij of each channel means a channel from the j-th transmitting node to the I-th receiving node. The precoding filter, the relay filter, and the interference cancellation filter at the destination node, transmitted from each source,

,

,

Can be expressed in the form of a matrix as shown in FIG.

First, the received signal received by the kth type X relay in the first phase is as follows.

[Equation 1]

는 잡음 신호를 의미하며,

은 m번째 소스 노드에서 보낸 정보 신호를 의미한다.At this time,

Means a noise signal,

Denotes an information signal transmitted from the m-th source node.

외에 서로 다른 타입의 릴레이 노드들로부터 오는 릴레이간 간섭 신호(Inter-Relay Interference, 이하 IRI)인

(Y=1 또는 2, Y≠X)를 받게 된다.As shown in Equation (1), each relay node is a desired signal received from the source nodes

And an inter-relay interference (IRI) signal from relay nodes of different types

(Y = 1 or 2, Y ≠ X).

In the second phase, the signal received by the I-th destination node through the type X relay group is as follows.

&Quot; (2) "

외에 ISI인

와 IRI인

를 받게 된다.As can be seen from Equation (2), the I-th destination node is a signal

In addition to ISI

And IRI

.

These three kinds of interference signals can be effectively removed by using the interference alignment technique, thereby improving the performance of the system. Hereinafter, the interference sorting scheme proposed by the multi-relay transmission apparatus according to the present invention will be described.

First, the interference condition between relay nodes can be expressed as follows.

&Quot; (3) "

와

를 일반적인 간섭 정렬 방법으로 설계하게 되면, 이전 단계에서의 릴레이 그룹 필터

의 계산에 영향을 주게 되고, 마찬가지로 순차적 전송 특성에 따라 다시 그 전 단계의 타입 X 릴레이 필터 설계에 연속적으로 영향을 주게 되어 필터 설계가 불가능해진다.At this time, in order to remove the IRI,

Wow

Is designed as a general interference sorting method, the relay group filter

And similarly affects the design of the type X relay filter in the previous stage in succession in accordance with the sequential transmission characteristic, so that the filter design becomes impossible.

과 간섭 정렬 행렬

로 나누어 표현한다. 여기서, 간섭 제거 행렬

은 제 1 페이즈에서 소스 노드들로부터 신호를 받을 때, 다른 릴레이 노드 그룹에서 오는 신호를 제거하는 역할을 하며, 간섭 정렬 행렬

는 제 2 페이즈에서 릴레이 노드가 소스 노드들로부터 받은 신호를 목적지 노드로 전달할 때, 이러한 신호가 다른 릴레이 노드 그룹에 정렬이 되도록 하는 역할을 수행한다. 두 필터는 모두

의 행렬 계수를 가지는데, 이는

개만큼의 간섭 정렬을 위한 공간을 위한 같이 정해진 릴레이 필터를 수식으로 표현하면 다음과 같다.Therefore, in the multi-relay transmission apparatus according to the present invention, a relay filter design suitable for eliminating the inter-relay interference signal generated in the sequential transmission scheme can be performed as follows. First, the relay filter is roughly divided into two matrices, and an interference elimination matrix

And an interference alignment matrix

. Here, the interference cancellation matrix

When receiving a signal from the source nodes in the first phase, serves to remove the signal from the other relay node group,

Plays a role of causing such a signal to be aligned with another relay node group when the relay node transfers the signal received from the source nodes to the destination node in the second phase. Both filters

Lt; RTI ID = 0.0 >

The following equations can be expressed as follows.

&Quot; (4) "

When the relay filter is designed as shown in Equation (4), in the first phase, the inter-relay interference alignment condition as shown in Equation (5) holds.

&Quot; (5) "

That is, when the Y-type relay nodes transmit signals to the destination node, the type X relay can first determine the interference cancellation filter from the condition of Equation (5).

Similarly, in the second phase, the following interference alignment condition holds.

&Quot; (6) "

That is, when the Type X relay node desires to transmit a signal to the destination node, the interference sorting filter can be designed so that it does not act as an interference signal to the Type Y relays.

와 같이 표현하면, 최종적으로 다음과 같은 소스 노드와 목적지 노드 간의 간섭 정렬 조건이 성립할 수 있게 된다. 이때,

은 소스 노드-목적지 노드 쌍이 보낼 수 있는 데이터 스트림 수를 의미한다.When the interference elimination filter and the interference alignment filter are obtained through the above process, the relay filter as shown in Equation (4) can be finally determined. If the determined relay filter is used, the effective channel between the source node and the destination node of

The interference condition between the source node and the destination node can be finally established as follows. At this time,

Is the number of data streams that a source node-destination node pair can send.

&Quot; (7) "

4 is a diagram showing a first phase state in a multi-relay transmission apparatus, and Fig. 5 is a diagram showing a second phase state in a multi-relay transmission apparatus.

In the multi-relay transmission apparatus according to the present invention, data is transmitted by applying an alternate transmission relaying technique. In FIG. 4 and FIG. 5, the source node 100 is represented by S, the relay node 200 by R, and the destination node 300 by D, and the I-th source node 100 and the destination node 300 are represented by S _i -D _i .

와 같이 위 첨자를 이용하여 표시한다. 그리고 소스 노드(100)와 목적지 노드(300) 쌍과 제 1 그룹 및 제 2 그룹의 릴레이 노드(210, 230)는 각각 K, K_a, K_b개가 존재한다.First, the first group relay node 210 receives a signal from the source nodes 100 in the first phase and transmits the signal received from the source node 100 in the second phase to the destination node 300. Conversely, the second group relay node 230 sends a signal to the destination node 300 in the first phase and receives a signal from the source node 100 in the second phase. The relay nodes of each group are

As shown in Fig. The pair of the source node 100 and the destination node 300 and the relay nodes 210 and 230 of the first group and the second group are K, K _a , and K _b , respectively.

The sequential transmission protocol proceeds through two steps of a first phase and a second phase. First, in the first phase, each source node 100 transmits a signal to the first group relay node 210 in the network. At this time, the second group relay node 230 transmits the signals received from the source node 100 to the destination node 300 in the previous step. In the second phase, each source node 100 sends a signal to the second group relay node 230, where the first group relay node 210 sends signals received in the first phase to the respective destination node 300 . The first phase and the second phase are alternately performed, and the two-phase transmission scheme is continuously performed.

6 is a diagram illustrating a multi-relay transmission method according to a second embodiment of the present invention.

The multi-relay transmission method according to the present invention first checks whether data to be transmitted is present in the source node (S610). If there is data to be transmitted, a step of selecting a relay node is performed (S620). Specifically, the source node may classify the plurality of relay nodes into the first group relay node and the second group relay node before transmitting the data to the plurality of relay nodes. To this end, a plurality of source nodes transmit a reference signal for channel estimation to a plurality of relay nodes, and the relay node receives the reference signal and calculates a channel state estimation value based on the reference signal. The calculated channel state estimate may then be transmitted back to the source node.

The source node may select a corresponding relay node that exceeds a predetermined channel state threshold value among the channel state estimation values transmitted by the plurality of relay nodes as the first group relay node. At this time, the relay nodes other than the relay node selected as the first group relay node among the plurality of relay nodes can be changed to the second group relay node.

On the contrary, a plurality of source nodes can select a corresponding relay node exceeding a predetermined channel state threshold value among the channel state estimation values as the second group relay node, and relay nodes other than the selected relay node to the first group relay node Can be changed. As described above, the multi-relay transmission method according to the present invention can flexibly select relay nodes to transmit data. That is, the relay node classified as the first group relay node may be classified as the second group relay node other than the first group in the next phase.

After the plurality of relay nodes are classified into the first group and the second group relay node, a first phase step is performed (S630). In the first phase, the source node transmits the preceding data to the first group relay node at the first transmission time corresponding to the unit frame transmission time, and the first group relay node receives the preceding data. At the same time, the second group relay node receiving the previous data of the preceding data from the source node transmits the previous data to the plurality of destination nodes.

Next, in a second phase step (S640), the source node transmits the following data following the preceding data to the second group relay node at the second transmission time following the first transmission time, and the second group relay node And at the same time transmits the preceding data received by the first group relay node to a plurality of destination nodes. The first phase step and the second phase step are continuously performed alternately when there is data to be transmitted from the source node. If the first and second phases are continuously alternated and the data transmission is completed, the transmission is terminated (S650).

Meanwhile, in the process of transmitting data, the first group relay node and the second group relay node remove the interference signal using the interference elimination filter and the interference sorting filter when receiving data from the source node or transmitting the data to the destination node.

The interference cancellation filter corresponds to a filter for removing interference signals from other group relay nodes when the relay node receives the preceding data or the following data from the plurality of source nodes. The interference sort filter prevents data from interfering with other group relay nodes when the relay node transmits preceding data or trailing data to a plurality of destination nodes. Based on these two filters, the relay node can remove the interference signal. Meanwhile, the formulas related to each filter for removing the interference signal at the relay node have been described in detail above, and will not be described below.

On the other hand, the plurality of source nodes may transmit precoded preceding data or trailing data to the first group relay node or the second group relay node based on the precoding filter. The plurality of destination nodes may remove the interference signal from the relay node and the interference signal from the source node based on the received interference cancellation filter. Such a precoding filter and a received interference canceling filter may be determined after the interference alignment condition is established as shown in Equation (7) described above.

FIG. 7 is a diagram illustrating a multi-relay transmission method according to a third embodiment of the present invention.

FIG. 7 shows a case where the multiple relay transmission method shown in FIG. 6 and the signal transmission method performed in the first phase and the second phase are reversed.

First, it is determined whether there is data to be transmitted from the source node (S710). If there is data to be transmitted, the plurality of relay nodes are classified as the relay nodes of the first group and the second group (S720).

If the first group relay node and the second group relay node are classified, the first phase step is performed (S730). In the first phase, the source node transmits the preceding data to the second group relay node at the first transmission time corresponding to the unit frame transmission time, and the second group relay node receives the preceding data. At the same time, the first group relay node receiving the previous data of the preceding data from the source node transmits the previous data to the plurality of destination nodes.

Next, in a second phase step (S740), in the second transmission time following the first transmission time, the source node transmits the following data following the preceding data to the first group relay node, and the first group relay node And at the same time transmits the preceding data received by the second group relay node to a plurality of destination nodes. The first phase step and the second phase step are continuously performed alternately when there is data to be transmitted from the source node. If the first and second phases are continuously alternated and the data transmission is completed, the transmission is terminated (S750).

In the multi-relay transmission method according to the third embodiment, as in the embodiment shown in FIG. 6, interference cancellation can be performed using an interference cancellation filter and an interference cancellation filter, and description thereof is omitted here. do.

8 is a graph comparing degrees of freedom of the present invention with those of the prior art.

Each graph shown in FIG. 8 is a simulation result of each model to compare the sum of total degrees of freedom according to the number of relays. Referring to the upper graph, the multi-relay transmission apparatus according to the present invention and the sequential transmission scheme ATR scheme (DF)), the sum of the degrees of freedom is larger than that of the conventional AF method. In addition, when the ATR scheme (DF) according to the present invention is applied, it can be seen that the sum of the degrees of freedom is the highest as compared with other schemes.

One embodiment of the present invention may also be embodied in the form of a recording medium including instructions executable by a computer, such as program modules, being executed by a computer. Computer readable media can be any available media that can be accessed by a computer and includes both volatile and nonvolatile media, removable and non-removable media. In addition, the computer-readable medium may include both computer storage media and communication media. Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Communication media typically includes any information delivery media, including computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave, or other transport mechanism.

While the methods and systems of the present invention have been described in connection with specific embodiments, some or all of those elements or operations may be implemented using a computer system having a general purpose hardware architecture.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

100: Source node 110: Relay node selector
120: Relay node changing unit 200: Relay node
210: first group relay node 211: channel state estimator
213: Relay filter generation unit 230: Second group relay node
231: Channel state estimation unit 233: Relay filter generation unit
300: destination node

Claims (11)

In a multiple relay transmission apparatus,
A first phase for transmitting preceding data at a first transmission time corresponding to a unit frame transmission time and a second phase for transmitting a preceding data following the preceding data at a second transmission time following the first transmission time, A plurality of source nodes,
A first group relay node receiving the preceding data from the source node in the first phase and transmitting the received preceding data in the second phase and a second group relay node receiving the trailing data from the source node in the second phase A plurality of relay nodes including a second group relay node for transmitting the received subsequent data in the first phase,
And a plurality of destination nodes for receiving the trailing data transmitted by the second group relay node in the first phase and receiving the preceding data transmitted by the first group relay node in the second phase,
Wherein the plurality of relay nodes comprise:
Further comprising a channel state estimation unit for calculating a channel state estimation value based on a reference signal for channel estimation received from the plurality of source nodes and transmitting the channel state estimation value to the source node,
Removing interference signals from other group relay nodes based on an interference cancellation filter when receiving the preceding data or the following data from the plurality of source nodes,
Wherein the data does not act as an interference signal to the other group relay node based on an interference alignment filter when transmitting the preceding data or the following data to the plurality of destination nodes. delete The method according to claim 1,
Wherein the plurality of source nodes comprise:
A relay node selector for selecting a corresponding relay node exceeding a predetermined channel state threshold value among the transmitted channel state estimation values as the first group relay node or the second group relay node;
And a relay node changing unit for changing the relay nodes other than the selected relay node among the plurality of relay nodes to a relay node of another group. The method according to claim 1,
Wherein the plurality of source nodes transmit the precoded data and the trailing data to the plurality of relay nodes based on a precoding filter. The method according to claim 1,
Wherein the plurality of destination nodes remove the interference signal from the relay node and the interference signal from the source node based on the received interference cancellation filter. In a multiple relay transmission method,
The first group relay node transmits the preceding data to the first group relay node at a source node at a first transmission time corresponding to a unit frame transmission time, and the first group relay node receives the preceding data, Performing a first phase in which the second group relay node receiving the data transmits the previous data to a plurality of destination nodes,
Wherein the second group relay node is operable to transmit subsequent data to the second group relay node at a second transmission time subsequent to the first transmission time and subsequent to the preceding data at the source node, And a second phase performing step of the first group relay node transmitting the received preceding data to the plurality of destination nodes,
Wherein the first group relay node and the second group relay node comprise:
Calculating a channel state estimation value based on a reference signal for channel estimation received from the plurality of source nodes, transmitting the channel state estimation value to the source node,
Removing interference signals from other group relay nodes based on an interference cancellation filter when receiving the preceding data or the following data from the plurality of source nodes,
Wherein the data is prevented from acting as an interference signal to the other group relay node based on an interference sorting filter when transmitting the preceding data or the following data to the plurality of destination nodes. delete The method according to claim 6,
Selecting a corresponding relay node as a first group relay node in which the plurality of source nodes exceed a predetermined channel state threshold value among the channel state estimation values;
And changing the remaining relay nodes of the plurality of relay nodes except for the first group relay node to the second group relay node. The method according to claim 6,
Selecting a corresponding relay node as a second group relay node in which the plurality of source nodes exceeds a predetermined channel state threshold value among the channel state estimation values;
And changing the remaining relay nodes of the plurality of relay nodes except for the second group relay node to the first group relay node. The method according to claim 6,
Wherein the plurality of source nodes transmit the preceding data or the following data precoded based on a precoding filter to the first group relay node or the second group relay node. The method according to claim 6,
Wherein the plurality of destination nodes remove an interference signal from a relay node and an interference signal from a source node based on a received interference cancellation filter.

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