KR20120039419A - Apparatus and method for determning transmission power in a relay network and thereof relay network system - Google Patents

Abstract

PURPOSE: A transmission power determination apparatus in a relay network and relay network system are provided to minimize or optimized transmission power by calculating transmission power rates between a source node and a relay node. CONSTITUTION: A transmission power determination apparatus acquires a channel state within a relay network(910). When a predetermined condition is satisfied, the transmission power determination apparatus calculates transmission power rates by considering of the channel state(912, 914). In case the predetermined condition is not satisfied, the transmission power rate is determined to a predetermined value(916). The transmission power determination apparatus determines the transmission power according to the determined transmission power rates(918).

Description

Apparatus and method for determining transmission power in relay network and relay network system supporting the same {APPARATUS AND METHOD FOR DETERMNING TRANSMISSION POWER IN A RELAY NETWORK AND THEREOF RELAY NETWORK SYSTEM}

The present invention relates to an apparatus and method for determining power for transmitting signals in a relay network, and more particularly, to an apparatus and method for determining transmission power of a source node and a relay node constituting a relay network. And a relay network system providing the same.

In general, a relay network refers to a network that transmits a signal between a source node and a destination node by using a relay node to expand a service area.

For example, node information transmitted by the source node is received by the destination node and the relay node. The relay node relays the signal received from the source node to the destination node.

Therefore, the destination node may increase the reception probability of the signal by receiving the signal transmitted from the source node and the signal transmitted from the relay node.

The most representative technology of the relay network is a relay-based network used in a wireless personal area network (WPAN) based on IEEE 802.15.3.

In such relay networks, it is common to use limited power internally. That is, there may be many source and relay nodes in the relay network, where the source and relay nodes share the total power allowed in the relay network for signal transmission.

For this reason, it is desirable to use optimized power in transmitting signals from the source node and the relay node constituting the relay network. Therefore, in order to transmit signals while guaranteeing the performance of a relay network for Green IT or ECO systems, a method for minimizing and optimizing power to be used for signal transmission must be prepared.

As a preferred embodiment, an apparatus and method for determining an optimal transmission power ratio for maximizing outage probability performance in a relay network relaying a signal by a complex relay scheme and a relay network system supporting the same are provided.

In addition, as a preferred embodiment, an apparatus and method for reducing power usage for transmitting signals while maintaining transmission performance in a relay network relaying signals by a complex relay scheme, and a relay network system supporting the same are proposed.

In another preferred embodiment, an apparatus and method for determining transmission power at a source node and a relay node in consideration of channel conditions of each node in a relay network relaying signals by a complex relay scheme and a relay network system supporting the same are proposed. do.

In another preferred embodiment, an apparatus and method for determining a transmission power ratio between a source node and a relay node in consideration of spectral density and noise power in a relay network relaying signals by a complex relay technique; We propose a relay network system that supports this.

In a method for determining transmission power at a source node or a relay node of a relay network relaying a signal by a complex relay scheme according to an exemplary embodiment, a first channel situation between the source node and the relay node, and the relay node and the object may be used. Acquiring a second channel situation between nodes; and if the object value calculated based on spectral density and noise power is equal to or greater than a reference value calculated by the acquired first and second channel conditions, the object value and the acquisition. Calculating a transmission power ratio between the transmission power of the source node and the transmission power of the relay node based on the first and second channel conditions, and when the target value is less than the reference value, the transmission power of the source node. Determining a transmission power ratio of the relay node to a preset value, and calculating or determining By Shin-power ratio comprises the step of determining the transmit power of the source node or the relay node.

In addition, according to an embodiment of the present invention, an apparatus for determining transmission power at a source node or a relay node of a relay network relaying a signal by a complex relay scheme may include a first channel situation between the source node and the relay node and the relay node. A channel estimator for acquiring a second channel situation between the target nodes, and a reference value calculated by the first and second channel conditions obtained by the channel estimator from a target value calculated based on spectral density and noise power; In the above case, the transmission power ratio between the transmission power of the source node and the transmission power of the relay node is calculated based on the target value and the obtained first and second channel conditions, and the target value is less than the reference value. A transmission power ratio determination unit that determines the transmission power ratio as a preset value, and the transmission ratio determination unit It comprises by calculation or the determined transmission power ratio of the transmission power determining unit for determining the transmit power of the source node or the relay node.

In addition, according to a preferred embodiment, a relay network system for relaying a signal by a complex relay scheme, the source for obtaining the transmission power ratio based on the channel conditions in the relay network, and determines the transmission power based on the obtained transmission power ratio A node and a relay node, and a destination node for receiving a signal transmitted by the determined transmission power,

The source node and the relay node,

If the target value calculated based on the spectral density and the noise power is less than the reference value calculated by the first channel situation between the source node and the relay node and the second channel situation between the relay node and the destination node, the source node. The transmission power ratio, which is a ratio between the transmission power of and the transmission power of the relay node, is determined as a preset value. When the target value is greater than or equal to the reference value, the target value and the acquired first and second channel conditions are determined. The transmission power ratio is calculated based on the above.

According to the proposed exemplary embodiment, it is possible to minimize and optimize the transmission power used for transmitting signals at the source node and the relay node in a relay network system relaying signals by a complex relay scheme.

On the other hand various other effects will be disclosed directly or implicitly in the detailed description of the embodiments of the present invention to be described later.

1 illustrates a communication protocol according to a decode-and-forward scheme in a relay network;
2 illustrates a communication protocol according to an Amplify-and-Forward scheme in a relay network;
3 to 5 are diagrams illustrating a communication protocol by an incremental relaying technique in a relay network according to an embodiment of the present invention;
FIG. 6 is a diagram showing an experimental result comparing the gains due to the outage probability performance when the complex incremental relay technique is applied and when the incremental relay technique is applied; FIG.
7 illustrates a communication protocol performed by a cooperative relay scheme in a cooperative relay network.
8 illustrates a communication protocol performed by a complex cooperative relay scheme in a cooperative relay network.
9 is a graph according to an experimental result showing that outage probability performance by a complex cooperative relay technique is better than outage probability performance by a cooperative relay technique.
10 is a view showing the configuration of a source node constituting a relay network according to a preferred embodiment;
11 is a view showing the configuration of a relay node constituting a relay network according to an embodiment of the present invention;
12 illustrates a control flow performed by a source node and a relay node to determine transmission power in a complex incremental relay network according to a preferred embodiment.

In the following description of the present invention, detailed descriptions of well-known functions or configurations will be omitted if it is determined that the detailed description of the present invention may unnecessarily obscure the subject matter of the present invention. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be based on the contents throughout this specification.

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

1 illustrates a communication protocol according to a decoding-and-forward (hereinafter, referred to as "DF" f) technique in a relay network.

Referring to FIG. 1, a signal transmitted from a source node is received by an adjacent relay node as well as a destination node. The relay node decodes the signal received from the source node, recodes the decoded signal, and transmits the decoded signal to the destination node.

The destination node decodes the signal received from the source node and the signal received from the relay node, and combines the two decoded signals to obtain a desired signal.

2 shows a communication protocol according to an Amplify-and-Forward (hereinafter, referred to as "AF") technique in a relay network.

2, a signal transmitted from a source node is received by an adjacent relay node as well as a destination node. The relay node amplifies the signal received from the source node as it is and transmits it to the destination node. That is, when the relay network supports the AF scheme, the relay node does not decode the signal received from the source node.

The destination node decodes the signal received from the source node and the signal received from the relay node, and combines the two decoded signals to obtain desired information.

As described above, in the case of the DF scheme, the relay node performs a function of decoding and re-encoding the information of the received source node, thereby increasing complexity due to signal processing of the relay node, and incorrect information is caused by incorrect decoding. Can be sent.

On the other hand, in the case of the AF technique, the relay node has a simple function, and amplified and transmitted signals can provide improved performance. However, in the AF technique, the received noise components may be amplified and transmitted together.

Therefore, in the relay network, it is preferable to select one of the DF technique and the AF technique in consideration of the channel condition or the performance of the relay node and use it as a communication protocol.

In addition, a communication protocol for obtaining diversity gain in a relay network has been proposed. The diversity gain here is used to include the diversity gain due to retransmission in addition to the diversity gain by the signals received from the source node and the relay node at the destination node.

The communication protocols applicable to obtain additional diversity gains in the relay network include an incremental relay scheme, a coded cooperation relay scheme, and the like.

First, the incremental relay scheme is a communication protocol in which a hybrid retransmission (HARQ) scheme is applied to improve the performance of information transmission through additional diversity gain, and the relay node notifies the signal only when the target node fails to receive the signal. It is a technique to retransmit to the destination node. That is, when the destination node succeeds in directly receiving the signal transmitted by the source node, the relay node does not need to transmit the signal received from the source node to the destination node.

Thus, in relay networks using incremental relay schemes, not only can channel waste be reduced, but also diversity gain can be obtained.

However, the general incremental relay technique does not consider the channel situation between the source node and the relay node. Therefore, as a new communication protocol considering channel conditions between the source node and the relay node, a hybrid incremental relay scheme has been proposed.

The complex incremental relay scheme is a communication protocol for selectively applying AF and DF by retransmission according to whether the received signal is successfully decoded when the relay node retransmits a signal received from a source node to a target node.

Next, the cooperative relay scheme further delivers surplus information (parity) using the channel code to the target node, and causes the target node to decode the desired information by the initially received information and the additionally received surplus information. Communication protocol. That is, it is a communication protocol for cooperatively transmitting signals for each node over two frames. For example, a signal is transmitted for each node in the first frame, and a signal (surplus information) received by each node in the first frame is transmitted in the second frame.

In addition to the general cooperative relay scheme, a hybrid coded cooperation relay scheme is proposed in which redundant information is selected and transmitted in consideration of channel conditions.

In the hybrid cooperative relaying scheme, a first node transmits its own signal to a destination node and a second node (relay node) in a first frame, and responds to a channel condition of the second node (relay node) in a second frame. It is a communication protocol for transmitting a selected transmission signal (redundancy information according to a signal transmitted from the first frame or a signal received from the second node) by a selected relay technique (DF technique or AF technique).

In the following description, for convenience, the term 'composite relay technique' is collectively referred to as a complex incremental relay technique and a complex cooperative relay technique. A relay network relaying a signal by the hybrid relay scheme will be referred to as a hybrid relay network.

In addition, a general incremental relay technique will be referred to as an 'incremental relay technique', and a general cooperative relay technique will be referred to as a 'cooperative relay technique'. A relay network relaying a signal by the incremental relay technique is called an "incremental relay network", and a relay network relaying a signal by the cooperative relay technique is called a "cooperative relay network".

Hereinafter, a composite increment relay method among an incremental relay method and a composite relay method will be described with reference to FIGS. 3 to 5, and a composite cooperative relay method among a cooperative relay method and a composite relay method will be described with reference to FIGS. 7 and 8.

3 to 5 show communication protocols performed in an incremental relay network.

As defined above, a communication protocol using an incremental relay scheme to be described with reference to FIGS. 3 to 5 may be classified into two types depending on whether channel conditions between a source node and a relay node are considered. That is, there are general incremental relay schemes that do not consider the channel situation between the source node and the relay node, and complex incremental relay schemes that consider the channel situation between the source node and the relay node.

The communication protocol by the general incremental relay scheme is performed by FIGS. 3 and 4, and the communication protocol by the complex incremental relay scheme is performed by FIG. 5 in addition to FIGS. 3 and 4.

Referring to Figures 3 and 4 will be described a procedure commonly applied in the communication protocol by the general incremental relay scheme and the communication protocol by the complex incremental relay scheme.

3 illustrates a situation in which a source node transmits a signal in a first frame in an incremental relay network.

Referring to Figure 3, the signal transmitted by the source node is received by the destination node and the relay node. The destination node decodes the signal received from the source node and provides the decoded result to the source node.

The destination node may provide the decoding result to the source node only when the decoding of the signal received from the source node fails or succeeds. For this purpose, when the decoding result is not provided by the destination node for a preset time, the source node must be promised in advance to recognize that the destination node has failed or succeeded in decoding the signal.

If the destination node succeeds in decoding the signal received from the source node in the first frame, the source node requests the relay node not to transmit the signal transmitted to the destination node. The request corresponds to the source node sending a relay abort request message to the relay node.

When a relay stop request is received from the source node, the relay node does not relay the signal received from the source node to the destination node in the first frame. In this case, the relay node may discard the signal received from the source node.

4 illustrates a situation in which a signal of a source node is relayed in a second frame in an incremental relay network. In this case, it is assumed that the relay node succeeds in decoding the signal received from the source node.

Referring to FIG. 4, when the source node recognizes that the destination node has failed to decode its transmitted signal, the source node requests the relay node to transmit the previously transmitted signal to the destination node. The request may assume that a relay stop request is not provided until a relay request is made from the source node to the relay node or a predetermined time elapses.

The relay node then determines whether the decoding of the signal previously received from the source node was successful.

In FIG. 4, since it is assumed that the decoding of the signal received from the source node by the relay node is successful, the relay node encodes the signal that has been successfully decoded by the DF technique and delivers the signal to the destination node.

As described above, the above operation corresponds to a communication protocol according to a general incremental relay technique.

The general incremental relay scheme only considers channel characteristics between a source node and a destination node. In other words, channel characteristics between the source node and the relay node are ignored, and the case where the destination node and the relay node fail to decode the signal transmitted by the source node at the same time is not considered.

In other words, the communication protocol based on the general incremental relay technique assumes that the relay node unconditionally succeeds in decoding the signal received from the source node.

Therefore, the additional procedure of the communication protocol by the complex incremental relay scheme, which will be described later, considers a case where the destination node and the relay node fail to decode a signal transmitted from the source node at the same time.

FIG. 5 illustrates a communication protocol for relaying a signal received from a source node by a complex incremental relay method when a relay node fails to decode a signal received from a source node.

Referring to FIG. 5, when the source node recognizes that the decoding of the signal transmitted by the target node has failed, it requests the relay node to transmit the signal previously transmitted by the target node to the target node. This considers a case where a relay stop request is not provided until a relay request is made from the source node to the relay node or a predetermined time elapses.

The relay node then determines whether the decoding of the signal previously received from the source node was successful. Since it is assumed in FIG. 5 that the signal received from the source node has failed, the relay node will recognize that the decoding of the signal received from the source node has failed.

In this case, the relay node transmits a signal received from the source node to the destination node by an AF technique. That is, the relay node amplifies the signal received from the source node and transmits it to the destination node.

FIG. 6 shows an experimental result comparing the gains due to the outage probability performance when the complex incremental relay technique is applied and when the incremental relay technique is applied. According to FIG. 6, it can be seen that a relatively good outage probability performance can be obtained when the incremental relay technique is applied when the incremental relay technique is applied.

7 shows a communication protocol performed by a cooperative relay scheme in a cooperative relay network.

As defined above, the communication protocol based on the cooperative relay scheme to be examined by FIG. 7 determines a signal to be transmitted to the destination node in consideration of the channel condition between the source node and the relay node.

In FIG. 7, four cases are assumed according to channel conditions between a first user and a second user corresponding to two transmitting nodes. In this case, the first user serves as a source node in the cooperative relay network and corresponds to the second user. The second user serves as a source node in the cooperative relay network and corresponds to the relay node corresponding to the first user.

Therefore, when applying the cooperative relay scheme, four cases can be generated depending on whether the first user and the second user each decode or decode the signal received from the counterpart user.

In the first case, both the first and second users successfully receive the signal transmitted by the counterpart user. In the second case, both the first and the second user fail to receive the signal sent by the counterpart user. If it is. The third case is when the first user fails to receive a signal transmitted by the second user, but the second user successfully receives the signal transmitted by the first user. Finally, the fourth case is the reverse of the third case, in which the first user succeeds in receiving a signal transmitted by the second user but the second user fails in receiving a signal transmitted by the first user. to be.

Referring to FIG. 7, the first and second users transmit their signals to the counterpart user and the destination node in the first frame. As a result, the first user receives and decodes the signal transmitted by the second user, and the second user receives and decodes the signal transmitted by the first user.

One of the four cases previously defined by the decoding result by the first and second users will occur.

As in the first case, when each user successfully decodes the signal received from the counterpart user, the surplus information of the received signal (relative information) that is successfully decoded is transmitted in the second frame. According to the operation corresponding to the first case, the diversity gain can be obtained by transmitting the surplus information of the other party rather than the surplus information of the second frame.

As in the second case, if all of the users fail to decode the signal received from the counterpart user, the second frame transmits its own excess information instead of sending the counterpart extra information.

As in the third and fourth cases, if some of the users succeed in decoding the received signal but the other user fails to decode the received signal, the user who succeeded in decoding the surplus of the received signal (relative information) that succeeded in decoding. Send information in the second frame. And the user who failed in decoding transmits his surplus information.

Accordingly, in the third case, the first user who fails to decode the received signal transmits its surplus information in the second frame, and the second user who successfully decodes the received signal transmits surplus information of the other party in the second frame. As a result, both the first and second users transmit surplus information of the first user.

In the fourth case, the first user who successfully decodes the received signal transmits surplus information of the other party in the second frame, and the second user who fails to decode the received signal transmits its surplus information in the second frame. As a result, both the first and second users transmit surplus information of the second user.

However, in the above-described cooperative relay technique, when the probability that only a signal of an arbitrary user does not succeed is increased, a situation in which the performance of the arbitrary user decreases unilaterally occurs. For example, if the third case occurs frequently, only the surplus information of the first user may be transmitted, and the performance of the second user may be degraded. If the fourth case occurs frequently, only the surplus information of the second user is delivered and thus the first user is transmitted. User performance may be degraded.

To cope with this problem, the communication protocol is a complex cooperative relay technique. The complex cooperative relay scheme does not transmit the signal because the decoding of the received signal has failed, and thus the transmission scheme is different. For example, the complex cooperative relay scheme transmits the received signal by the DF technique when the decoding of the received signal is successful, and transmits the received signal by the AF technique when the decoding of the received signal fails. This can solve the performance degradation caused by the imbalance of the transmission signal that can occur in the cooperative relay technique.

8 shows a communication protocol performed by a complex cooperative relay scheme in a cooperative relay network.

Referring to FIG. 8, if all users succeed in decoding the signal received in the first frame as in the first case, all users transmit a signal that succeeds in decoding by the DF technique. For example, the first user decodes a signal received from the second user and then encodes and transmits a signal that succeeded in decoding. The second user decodes a signal received from the first user and then encodes and transmits a successful signal. .

However, if all users failed to decode the signal received in the first frame as in the second case, all users transmit the signal that failed to decode, that is, the received signal by the AF technique. For example, the first user amplifies and transmits the signal received from the second user, and the second user amplifies and transmits the signal received from the first user.

If the user who successfully decodes the received signal coexists with the user who failed, as in the third and fourth cases, the user who has successfully decoded encodes and transmits the corresponding signal, and the user who fails in decoding amplifies and transmits the received signal. .

FIG. 9 is a graph according to an experimental result showing that outtage probability performance by a complex cooperative relay technique is better than outage probability performance by a cooperative relay technique.

Meanwhile, the communication protocol for the complex relay scheme described above assumes the use of a transmission power ratio that equally allocates transmission power to each user, that is, a transmission node (source node, relay node). However, in a relay network using a complex incremental relay scheme, assigning the same or similar transmit power to each transmitting node is not an optimization of the relay network performance.

Therefore, it is desirable to determine the transmission power ratio between transmitting nodes so as to optimize the performance of a relay network using a complex incremental relay technique. In this case, the transmission power ratio means a ratio of transmission power to be used by a plurality of transmission nodes. For example, the transmission power ratio may be a ratio of transmission power of a source node and transmission power of a relay node.

To this end, in a preferred embodiment to be described later, it is assumed that the sum of the transmission powers of a relay network using a complex relay scheme and all users (nodes transmitting signals) in the relay network is equal to the total power available in the relay network. do.

In addition, in the preferred embodiment, it is assumed that the source node or the relay node that determines the transmission power ratio knows all the current channel conditions in the relay network. That is, it is assumed that the state of each channel can be measured based on channel state information (CSI) of all channels existing in the relay network.

Meanwhile, in the preferred embodiment, under the above-described assumption, an optimal transmission power ratio for at least two users (transmission nodes) is obtained based on the current channel situation (channel change, etc.). The transmission power for each user (transmission node) is determined using the obtained transmission power ratio, so that each user (transmission node) can transmit a signal by the determined transmission power.

This makes it suitable for situations where systems like Green IT or ECO systems want to get the most out of minimal power.

Hereinafter, an apparatus and method for determining transmission power for a plurality of transmission nodes in a relay network and a relay network system supporting the same will be described in detail.

To this end, a detailed method for obtaining an optimal transmit power ratio for maximizing outage probability performance in a relay network using a complex relay scheme will be described.

In addition, in a preferred embodiment to be described later will be described with respect to one source node and one relay node as a transmitting node in the relay network. However, it is obvious that the preferred embodiment to be applied may be equally applied even if more transmission nodes are targeted.

10 illustrates a configuration of a source node constituting a relay network according to an exemplary embodiment.

Referring to FIG. 10, the receiver 710 is coupled to an antenna to receive a signal transmitted through a wireless network. The received signal is transmitted to the decoder 712. Since the operation performed by the receiver 710 is not directly related to the present invention, a detailed description thereof will be omitted.

The decoder 712 decodes a signal provided from the receiver 710. The decoder 712 provides the decoding result of the signal to the controller 720. The coder 714 encodes a signal to be transmitted under the control of the controller 720 and outputs the signal to the transmitter 716.

The transmitter 718 transmits the encoded signal output from the coder 714 through the antenna under the control of the controller 720. In order for the transmitter 718 to transmit the encoded signal, it is necessary to determine the transmission power.

The transmission power is determined by the channel estimator 718, the transmission power ratio determiner 722, and the transmission power determiner 724. In FIG. 10, it is assumed that the transmission power ratio determination unit 722 and the transmission power determination unit 724 are provided in the control unit 720. However, it is apparent that the transmission power ratio determination unit 722 and the transmission power determination unit 724 may be configured independently without being in another configuration.

Therefore, in the following description, although the configuration for determining the transmission power ratio and the configuration for determining the transmission power are described as present in the control unit, the proposed preferred embodiment should not be construed as limited thereto.

The channel estimator 718 estimates a situation of channels being used in the relay network based on the signal received through the receiver 710. The situation of the channels may be estimated directly by the received signal but may be obtained by control information provided from another node. In a particularly preferred embodiment, the channel situation between the source node and the relay node and the channel condition between the relay node and the destination node must be obtained. In addition, it is natural that all known techniques for acquiring the channel situation can be borrowed for the preferred embodiment.

The obtained channel condition information is transmitted to the transmission power ratio determination unit 722 to determine the transmission power ratio.

The controller 720 controls not only the overall operations of the decoder 712 and the coder 714 but also the operations of the receiver 710 and the transmitter 716.

)을 결정한다.The transmission power ratio determiner 722 uses the information on the channel condition provided by the channel estimator 718 or the information on the channel condition that is already known, and the transmission power ratio and the signal transmitted by the channel estimator 718 are used. Ratio between transmit power of at least one relay relaying to the node (transmission power ratio,

Is determined.

)은 하기 <수학식 1>에 의해 계산될 수 있다.The transmit power ratio (

) Can be calculated by Equation 1 below.

로 정의되며, R은 스펙트럼 밀도를 의미하고,

는 잡음 전력을 의미한다. 그리고

는 소스 노드와 릴레이 노드 간의 채널 변화의 측정 값 (제1채널 상황)이고,

는 릴레이 노드와 목적 노드 간의 채널 변화의 측정 값 (제2채널 상황)이다.Where the target value K is

R is defined as spectral density,

Means noise power. And

Is the measured value of the channel change between the source node and the relay node (first channel situation),

Is the measured value of the channel change between the relay node and the destination node (second channel condition).

은 K를 기준으로 정리하면,

와 같다. 상기 K를 기준으로 정리된

은 송신 전력 비율을 결정하기 위한 기준 값이 된다. On the other hand, one of the conditions used to determine the transmission power ratio in Equation 1

Is based on K,

Same as Summarized based on K

Is a reference value for determining the transmission power ratio.

에 의해 송신 전력 비율을 결정한다. 하지만 상기 대상 값 K가 상기 기준 값 미만인 경우에는 상기 <수학식 1>에서 두 번째로 정의하고 있는 미리 결정된 값에 의해 송신 전력 비율을 결정한다. 상기 <수학식 1>에 의하면, 상기 미리 결정된 값은 0.5임을 알 수 있다.That is, when the target value K is greater than or equal to the reference value, the first value defined in Equation 1 is defined.

The transmission power ratio is determined by. However, when the target value K is less than the reference value, the transmission power ratio is determined by the second predetermined value defined in Equation (1). According to Equation 1, the predetermined value is 0.5.

Equation 1 is derived from the experiment to obtain an optimal transmission power ratio between the source node and the relay node when the power of the entire network is limited in the complex incremental relay network. Therefore, when the transmission power of the source node and the relay node is determined according to Equation 1, the network performance can be improved, and the network situation where the maximum effect should be achieved with the minimum power such as Green IT or ECO system. It is a suitable solution.

)을 기반으로 대상 값 (K)을 계산한다. 그리고 소스 노드와 릴레이 노드 간의 채널 변화에 대한 측정 값 (제1채널 상황)

과, 릴레이 노드와 소스 노드 간의 채널 변화에 대한 측정 값 (제2채널 상황)

에 의해 기준 값을 계산한다.As described above, when the operation of the transmission power ratio determination unit 722 is summarized, the transmission power ratio determination unit 722 has a spectral density (R) and a noise power (

Calculate the target value (K) based on And the measured value of the channel change between the source node and the relay node (first channel situation)

And the measured value of the channel change between the relay node and the source node (second channel situation)

Calculate the reference value by.

Thereafter, when the target value is greater than or equal to the reference value, the transmission power ratio determination unit 722 calculates a transmission power ratio based on the target value and the obtained first and second channel conditions. When the target value is less than the reference value, the transmission power ratio is determined as 0.5, which is a preset value.

As defined above, since the transmission power ratio is a ratio between the transmission power of the source node and the transmission power of the relay node, when the transmission power ratio is 0.5, the transmission power of the source node is about twice as high as the transmission power of the relay node. Has a power value.

Assuming a different channel change by the above-described scheme, an example of the transmission power ratio that can be obtained in each channel change is shown in Table 1 below.

는 전체 전송 데이터 중에 첫 번째 프로임에 보내는 정보의 비율을 의미한다.As defined in Table 1 above.

Is the ratio of the information sent to the first frame of the total transmission data.

The transmission power ratio determined by the transmission power ratio determination unit 722 is provided to the transmission power determination unit 724.

The transmission power determination unit 724 determines its own transmission power based on the transmission power ratio provided by the transmission power ratio determination unit 722. That is, the transmission power determiner 724 determines the transmission power of the source node based on the transmission power ratio.

Of course, the transmission power determiner 724 may determine the transmission power of the relay node based on the transmission power ratio. That is, the transmission power of the relay node may be determined by the source node, and the determined transmission power may be provided to the relay node.

The transmission power determination unit 724 controls the transmission power of the transmission unit 718 by the determined transmission power. Therefore, the transmitter 718 transmits a signal by the determined transmission power.

11 illustrates a configuration of a relay node constituting a relay network according to an exemplary embodiment.

Referring to FIG. 11, the receiver 810 is coupled to an antenna to receive a signal transmitted through a wireless network. The received signal is transmitted to at least one of the decoder 812, the channel estimator 826, and the amplifier 816. Since the operation performed by the receiver 810 is not directly related to the preferred embodiment, a detailed description thereof will be omitted. The receiver 810 only receives a signal transmitted by a source node for the preferred embodiment, and transmits the received signal to at least one of the decoder 812, the amplifier 816, and the channel estimator 828. Provided as a configuration.

The decoder 812 decodes a signal provided from the receiver 810. The decoder 812 provides a decoding result of the signal to the controller 820. When the decoder 812 succeeds in decoding the signal, the decoder 812 provides the decoded signal to the coder 814.

The coder 814 recodes the decoded signal provided from the decoder 812 under the control of the controller 820 and outputs the decoded signal to the transmitter 818. The control unit 820 instructs the coder 814 to encode a signal that succeeded in decoding when there is a relay request from the source node and the decoding of the received signal by the decoder 812 succeeds.

The amplifier 816 amplifies a signal provided from the receiver 810 under the control of the controller 820 and outputs the amplified signal to the transmitter 818. The control unit 820 instructs the amplifying unit 816 to amplify the received signal when there is a relay request from the source node and the decoder 812 fails to decode the received signal. .

The transmitter 818 transmits a signal output from one of the coder 814 and the amplifier 816 to an object node through an antenna under the control of the controller 820. However, the transmission of the signal to the destination node by the transmitter 818 is limited to the case where a relay request is received from the source node. If there is a relay stop request from the source node, the controller 820 will instruct the transmitter 818 not to transmit a signal to the destination node.

The controller 820 determines whether to transmit a signal received by the relay request and the relay stop request from the source node to the destination node. That is, when the relay of the corresponding signal is requested from the source node, the signal received from the source node is controlled to be delivered to the target node. However, if the relay of the corresponding signal is not requested from the source node, the signal received from the source node is controlled so as not to be delivered to the destination node.

On the other hand, when the relay of the signal is requested from the source node, the controller 820 may indirectly recognize that the decoding of the signal has failed by the target node. If the relay of the signal is not requested from the source node, the target node may indirectly recognize that decoding of the signal has been successfully performed.

In addition, the controller 820 controls the coder 814 or the amplifier 816 based on whether the decoding of the signal received from the decoder 812 is successful. That is, if the decoding of the signal received by the decoder 812 is successful, the control unit 816 instructs the coder 814 to encode the signal of the successful decoding. Otherwise, if decoding of the signal received by the decoder 812 fails, the controller 820 instructs the amplifying unit 816 to amplify the received signal.

The transmitter 818 transmits the encoded signal output from the coder 814 or the amplified signal output from the amplifier 816 under the control of the controller 820 through an antenna. In order for the transmitter 818 to transmit the encoded signal, it is necessary to determine transmission power.

The transmission power is determined by the channel estimator 826, the transmit power ratio determiner 822, and the transmit power determiner 824. In FIG. 11, it is assumed that the transmission power ratio determination unit 822 and the transmission power determination unit 824 are provided in the control unit 820. However, it is apparent that the transmission power ratio determination unit 822 and the transmission power determination unit 824 do not exist in other configurations and may be configured independently.

Therefore, in the following description, although the configuration for determining the transmission power ratio and the configuration for determining the transmission power are described as present in the control unit, the proposed preferred embodiment should not be construed as limited thereto.

The channel estimator 826 estimates the situation of channels being used in the relay network based on the signal received through the receiver 810. The situation of the channels may be estimated directly by the received signal but may be obtained by control information provided from another node. In a particularly preferred embodiment, the channel situation between the source node and the relay node and the channel condition between the relay node and the destination node must be obtained. In addition, it is natural that all known techniques for acquiring the channel situation can be borrowed for the preferred embodiment.

The obtained channel condition information is transmitted to the transmission power ratio determination unit 824 to determine the transmission power ratio.

The controller 820 controls not only the overall operations of the decoder 812, the coder 814, and the amplifier 816, but also the operations of the receiver 810 and the transmitter 816.

)을 결정한다. 상기 송신 전력 비율 (

)은 앞에서 정의된 <수학식 1>에 의해 계산될 수 있다.The transmission power ratio determination unit 820 uses the information on the channel condition provided by the channel estimating unit 826 or the information on the known channel condition to determine the transmission power ratio (

Is determined. The transmit power ratio (

) Can be calculated by Equation 1 defined above.

)을 기반으로 대상 값 (K)을 계산한다. 그리고 소스 노드와 릴레이 노드 간의 채널 변화에 대한 측정 값 (제1채널 상황)

과, 릴레이 노드와 소스 노드 간의 채널 변화에 대한 측정 값 (제2채널 상황)

에 의해 기준 값을 계산한다.When the operation of the transmission power ratio determination unit 822 is summarized, the transmission power ratio determination unit 822 may have a spectral density (R) and a noise power (

Calculate the target value (K) based on And the measured value of the channel change between the source node and the relay node (first channel situation)

And the measured value of the channel change between the relay node and the source node (second channel situation)

Calculate the reference value by.

Thereafter, when the target value is greater than or equal to the reference value, the transmission power ratio determination unit 822 calculates a transmission power ratio based on the target value and the obtained first and second channel conditions. When the target value is less than the reference value, the transmission power ratio is determined as 0.5, which is a preset value.

As defined above, since the transmission power ratio is a ratio between the transmission power of the source node and the transmission power of the relay node, when the transmission power ratio is 0.5, the transmission power of the source node is about twice as high as the transmission power of the relay node. Has a power value.

The transmission power ratio determined by the transmission power ratio determination unit 822 is provided to the transmission power determination unit 824.

The transmit power determiner 824 determines its transmit power based on the transmit power ratio provided by the transmit power ratio determiner 822. That is, the transmission power determination unit 824 determines the transmission power of the relay node based on the transmission power ratio.

Of course, the transmission power determiner 824 may determine the transmission power of the source node based on the transmission power ratio. That is, the transmission power of the source node may be determined by the relay node, and the determined transmission power may be provided to the source node.

The transmission power determination unit 824 controls the transmission power of the transmission unit 818 by the determined transmission power. Therefore, the transmitter 818 transmits a signal output from the coder 814 or a signal output from the amplifier 816 by the determined transmission power.

12 illustrates a control flow performed by a source node and a relay node to determine transmission power in a complex incremental relay network according to an exemplary embodiment.

The control flow shown in FIG. 12 includes obtaining a channel condition, calculating or determining a transmission power ratio, determining a transmission power based on the transmission power ratio, and transmitting a signal by the determined transmission power. Process.

In the process of acquiring the channel condition, a first channel condition between a source node and a relay node and a second channel condition between the relay node and the destination node are obtained.

In the calculating of the transmission power ratio, when the target value calculated based on the spectral density and the noise power is equal to or larger than the reference value calculated by the obtained first and second channel conditions, the target value and the acquired first value. And calculating a transmission power ratio between the transmission power of the source node and the transmission power of the relay node based on the second channel condition.

In the determining of the transmission power ratio, when the target value is less than the reference value, the transmission power ratio of the source node and the transmission power ratio of the relay node are determined as a preset value.

In the process of determining the transmission power, the transmission power of the source node or the relay node is determined by the calculated or determined transmission power ratio, and in the process of transmitting the signal, the signal is transmitted using the determined transmission power.

Referring to FIG. 12, in step 910, a transmitting node (source node or relay node) acquires a channel condition in a relay network. The transmitting node may also estimate the channel condition in the relay network based on the received signal or obtain it by control information provided from another node.

In a particularly preferred embodiment, the channel condition (first channel condition) between the source node and the relay node and the channel condition (second channel condition) between the relay node and the destination node must be obtained. In addition, it is natural that all known techniques for acquiring the channel situation can be borrowed for the preferred embodiment.

가 될 수 있다. 상기 소정의 조건을 K를 기준으로 정리하면,

와 같다. 이때 상기 K는

로 정의된다.In step 912, the transmitting node determines whether the acquired channel condition satisfies a predetermined condition. The predetermined condition

. If the predetermined condition is summarized on the basis of K,

Same as Where K is

Is defined as

)을 기반으로 계산된 대상 값 (K)이 앞서 획득한 제1 및 제2채널 상황을 기반으로 하여 얻을 수 있는 기준 값

보다 크거나 같은 값을 갖는 것이다.Thus, the predetermined condition is the spectral density (R) and the noise power (

Reference value that can be obtained based on the first and second channel conditions obtained previously

Have a value greater than or equal to

If it is determined in step 912 that the predetermined condition is satisfied, the transmitting node proceeds to step 914. If the transmitting node determines that the predetermined condition is not satisfied, the transmitting node proceeds to step 916.

가 사용될 수도 있다. 이 경우 상기 소정의 조건을 K를 기준으로 정리하면,

와 같다.But under the above conditions

May be used. In this case, if the predetermined condition is summarized based on K,

Same as

)을 기반으로 계산된 대상 값 (K)이 앞서 획득한 제1 및 제2채널 상황을 기반으로 하여 얻을 수 있는 기준 값

보다 작은 값을 갖는 것이다.Thus, the predetermined condition is the spectral density (R) and the noise power (

Reference value that can be obtained based on the first and second channel conditions obtained previously

It has a smaller value.

를 사용할 경우에는 상기 912단계에서의 판단 결과에 따른 동작인 914단계와 916단계가 반대로 수행되어야 한다. 즉 상기 소정 조건을 만족하는 경우에는 916단계에 상응하는 동작이 수행되고, 상기 소정 조건을 만족하지 못하는 경우에는 914단계에 상응하는 동작이 수행된다.On a predetermined condition as above

In the case of using, steps 914 and 916, which are operations according to the determination result of step 912, must be performed in reverse. That is, when the predetermined condition is satisfied, the operation corresponding to step 916 is performed, and when the predetermined condition is not satisfied, the operation corresponding to step 914 is performed.

과 소스 노드의 송신 전력

의 비율인 송신 전력 비율 (

)을 결정한다. 상기 송신 전력 비율 (

)은 앞서 정의한 <수학식 1>에 의해 계산될 수 있다.When the transmitting node proceeds to step 914, the transmission power of the relay node in consideration of the previously obtained channel condition.

Transmit power of source and source nodes

Transmit power ratio, which is the ratio of

Is determined. The transmit power ratio (

) Can be calculated by Equation 1 defined above.

)을 미리 설정된 값 (일 예로 0.5)으로 결정한다.However, if the process proceeds to step 916, the transmitting node determines the transmit power ratio (

) Is determined as a preset value (for example, 0.5).

If the transmission power ratio is calculated in step 914 or the transmission power ratio is determined in step 916, the transmitting node determines the transmission power based on the calculated or determined transmission power ratio in step 918. The transmit power determines, as transmit power, the amount of power given to it by the transmit power ratio from the power available to all transmit nodes. The power available to the entire transmitting node is either the total power that can be used within the relay network or the total power that can be used in the transmitting node for transmitting signals to the same destination node or the signal of one source node and the one source node. Can be defined as one of the total power that can be used in at least one relay node relaying to the destination node.

Although not shown in FIG. 12, the transmission power of the transmission node other than the transmission node may be determined by the transmission power ratio. In this case, a process for transferring the determined transmission power of the other transmission node to the corresponding transmission node is further required.

When the transmission power for signal transmission is determined, the transmitting node transmits a signal using the determined transmission power in step 920.

On the other hand, but shown and described with respect to the preferred embodiment of the present invention, the present invention is not limited to the specific embodiments described above, in the technical field to which the invention belongs without departing from the spirit of the invention claimed in the claims Various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

For example, in the description of FIGS. 10 and 11, the configuration of the relay node and the source node has been described separately, but in the case of applying the complex cooperative relay scheme as the complex relay scheme, the configurations of FIGS. 10 and 11 may be provided for each node. This is because in the case of the complex cooperative relay scheme, each node performs an operation as a relay node as well as an operation as a source node. However, even if the complex cooperative relay scheme is applied, there is no change in the specific scheme for determining the transmission power ratio at each node.

Claims (12)

In the method of determining the transmission power at the source node or relay node of the relay network relaying signals by a complex relay technique,
Obtaining a first channel condition between the source node and the relay node and a second channel condition between the relay node and the destination node;
If the target value calculated based on the spectral density and the noise power is equal to or larger than the reference value calculated by the obtained first and second channel conditions, the target value and the acquired first and second channel conditions are used. Calculating a transmit power ratio between a transmit power of a source node and a transmit power of the relay node;
When the target value is less than the reference value, determining a transmission power ratio of the source node and a transmission power ratio of the relay node as a preset value;
And determining transmission power of the source node or the relay node based on the calculated or determined transmission power ratio. The method of claim 1,
The target value is

Calculated by the reference value

Is calculated by
Where R means spectral density,

Means noise power,

Is a measure of the channel change between the relay node and the destination node,

Is a measurement value of a channel change between a source node and a relay node. The method according to claim 1 or 2,
When the target value is greater than or equal to the reference value, the transmission power ratio is

Is calculated by
Where K means the target value,

Is a measurement value of a channel change between a source node and a relay node. The method of claim 3,
And when the target value is less than the reference value, the predetermined value to be determined as the ratio of the transmit power of the source node and the transmit power of the relay node is 0.5. An apparatus for determining transmission power at a source node or a relay node of a relay network relaying a signal by a complex relay technique,
A channel estimator for obtaining a first channel condition between the source node and the relay node and a second channel condition between the relay node and the destination node;
When the target value calculated based on the spectral density and the noise power is equal to or larger than a reference value calculated by the first and second channel conditions obtained by the channel estimator, the target value and the acquired first and second channels. Calculate a transmission power ratio between the transmission power of the source node and the transmission power of the relay node based on the situation, and determine the transmission power ratio to determine the transmission power ratio as a preset value when the target value is less than the reference value. Wealth,
And a transmission power determination unit that determines transmission power of the source node or the relay node based on the transmission power ratio calculated or determined by the transmission ratio determination unit. The method of claim 5, wherein the transmission power ratio determination unit,
The target value

Calculated by the reference value

Calculated by
Where R means spectral density,

Means noise power,

Is a measure of the channel change between the relay node and the destination node,

Is a measurement value of a channel change between a source node and a relay node. The transmission power ratio determination unit according to claim 5 or 6,
If the target value is greater than or equal to the reference value, the transmission power ratio

Calculated by
Where K means the target value,

Is a measurement value of a channel change between a source node and a relay node. The method of claim 7, wherein the transmission power determiner,
And the transmission power of the source node and the transmission power of the relay node are determined to be 0.5 when the target value is less than the reference value. In a relay network system for relaying signals by a complex relay scheme,
A source node and a relay node obtaining a transmission power ratio based on a channel condition in the relay network, and determining transmission power by the obtained transmission power ratio;
A destination node for receiving a signal transmitted by the determined transmission power,
The source node and the relay node,
If the target value calculated based on the spectral density and the noise power is less than the reference value calculated by the first channel situation between the source node and the relay node and the second channel situation between the relay node and the destination node, the source node. Determine the transmission power ratio, which is a ratio between the transmission power of and the transmission power of the relay node, to a preset value,
And when the target value is greater than or equal to the reference value, calculating the transmission power ratio based on the target value and the acquired first and second channel conditions. The method of claim 9, wherein the source node and the relay node,
The target value

Calculated by the reference value

Calculated by
Where R means spectral density,

Means noise power,

Is a measure of the channel change between the relay node and the destination node,

Is a measurement value of a channel change between a source node and a relay node. The method of claim 9 or 10, wherein the source node and the relay node,
If the target value is greater than or equal to the reference value, the transmission power ratio

Calculated by
Where K means the target value,

Is a measurement value of a channel change between a source node and a relay node. The method of claim 11, wherein the source node and the relay node,
And the transmission power of the source node and the transmission power of the relay node are determined to be 0.5 when the target value is less than the reference value.

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