KR101532838B1 - Method for processing signal in wireless communicstion with decision feedback receiver - Google Patents

Abstract

The present invention relates to a wireless signal processing method in a wireless communication environment in which a relay node is present and a detection feedback receiver is present.
A wireless signal processing method in a wireless communication environment having a detection feedback receiver according to an embodiment of the present invention is a wireless signal processing method in a wireless communication environment having a relay node and a detection feedback receiver, 1 filter value set, wherein the first set of filter values comprises a first filter value of a relay node and a first filter value of a transmitting node; Calculating a first set of filter values using a relay node based precoding scheme, the second set of filter values including a second filter value of a relay node and a second filter value of a transmitting node; And selecting one of the first filter value set and the second filter value set as a final filter value set.

Description

METHOD FOR PROCESSING SIGNAL IN WIRELESS COMMUNICATION WITH DECISION FEEDBACK RECEIVER FIELD OF THE INVENTION [0001]

The present invention relates to a wireless signal processing method, and more particularly, to a wireless signal processing method in a wireless communication environment in which a relay node exists and a detection feedback receiver is present.

In general, a relay node is used in a wireless communication system to solve a shadow area of a radio wave. The relay node receives and amplifies weak radio waves, and transmits the amplified signal again. To this end, a separate receiving antenna and transmitting antenna are required.

By using the relay node, the coverage of the base station is increased and the throughput is improved. That is, the system can improve the transmission rate by locating the relay node in a specific area having a poor channel environment, and can position the relay node near the cell boundary so that the terminal and the base station outside the coverage of the base station can communicate with each other.

In Korean Patent No. 10-0454564, a feedback signal is removed constantly by detecting a change with time of a feedback signal adaptively, thereby preventing a radio signal output from a transmission antenna from entering a reception antenna, A feedback canceling apparatus for a radio relay for mobile communication is disclosed.

However, Korean Patent No. 10-0454564 does not disclose a method of designing a filter of a repeater having a detection feedback receiver.

Therefore, it is necessary to study the wireless signal processing method in a wireless communication environment with a relay node and a detection feedback receiver.

An object of the present invention is to provide a wireless signal processing method in a wireless communication environment having a detection feedback receiver by obtaining optimal transmission, relay, and detection feedback filter values using a transmission node-based precoding method and a relay node-based precoding method .

According to an aspect of the present invention, there is provided a method of processing a wireless signal in a wireless communication environment including a relay node and a detected feedback receiver, the method comprising: calculating a first filter value set using a transmission node- Wherein the first set of filter values comprises a first filter value of a relay node and a first filter value of a transmitting node; Calculating a first set of filter values using a relay node based precoding scheme, the second set of filter values including a second filter value of a relay node and a second filter value of a transmitting node; And selecting one of the first set of filter values and the second set of filter values as a final set of filter values to provide a wireless signal processing method in a wireless communication environment having a detected feedback receiver.

The wireless signal processing method in a wireless communication environment having a detection feedback receiver according to an embodiment of the present invention can reduce the complexity in filter design while minimizing errors.

According to an embodiment of the present invention, it is possible to calculate optimum filter values in a wireless communication environment in which a relay node exists and a detection feedback receiver exists by using a transmission node-based precoding method and a relay node-based precoding method have.

1 is a diagram of a wireless communication system with a detected feedback receiver in accordance with an embodiment of the present invention.
2 is a flow diagram illustrating a wireless signal processing method in a wireless communication system environment with a detection feedback receiver in accordance with an embodiment of the present invention.
3 is a flowchart showing a method of setting a filter value by a transmission node-based precoding method in the radio signal processing method of FIG.
4 is a flowchart showing a method of setting a filter value by a relay node-based precoding method in the radio signal processing method of FIG.
5 to 6 are diagrams comparing the performance of the wireless processing method and other signal processing methods related to the present embodiment.

Hereinafter, a wireless signal processing method in a wireless communication environment having a detection feedback receiver according to an embodiment of the present invention will be described with reference to the drawings.

As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. In this specification, the terms "comprising ", or" comprising ", etc. should not be construed as necessarily including the various elements or steps described in the specification, Or may be further comprised of additional components or steps.

1 is a diagram of a wireless communication system with a detected feedback receiver in accordance with an embodiment of the present invention.

안테나 개수를 가진다. 데이터 스트림인

만큼의 데이터 신호를 보내는 공간 분할 시스템을 고려한다. 상기 무선 통신 시스템은 송신 노드(100)로부터 수신 노드(300)로의 직접 링크는 pathloss로 인해 신호가 매우 미약하므로 고려하지 않는다. 또한, 중계 노드(200)는 송신 및 수신 과정을 두 개의 hop에 걸쳐 진행되는 half duplex 방식을 고려하였다.As shown, a wireless communication system may include a transmitting node 100, a relay node 200, and a receiving node 300. The receiving node 300 is connected to a decision feedback receiver 310. The transmitting node 100, the relay node 200, and the receiving node 300

It has the number of antennas. Data stream

A spatial division system that transmits as many data signals as possible. In the wireless communication system, a direct link from the transmitting node 100 to the receiving node 300 is not considered because the signal is very weak due to pathloss. In addition, the relay node 200 considers the half duplex scheme in which transmission and reception processes are performed over two hops.

조건을 만족하는 송신 신호 벡터

는 송신 노드(100)의 필터(이하, '송신 필터'라 함)

의해 프리 코딩(precoding)되어 중계 노드(200)로 전송된다. 송신 필터는

조건을 만족한다는 가정 하에 송신 신호를 수학식 1과 같이 나타낼 수 있다.First, in the first hop considering the transmission process between the transmitting node 100 and the relay node 200,

A transmission signal vector satisfying the condition

(Hereinafter referred to as a "transmission filter") of the transmitting node 100,

And is then transmitted to the relay node 200. [ The transmit filter

The transmission signal can be expressed by Equation (1) under the assumption that the condition is satisfied.

The transmission power can be defined by Equation (2).

는 수학식 3과 같이 나타낼 수 있다.Thus, in the first time slot, the received signal vector of the relay node 200

Can be expressed by Equation (3).

는 송신 노드(100)와 중계 노드(200) 사이의 채널 매트릭스이며,

은 평균이 0이고, 공분산 매트릭스가

인 복소 백색 가우시안 노이즈 벡터이다.here

Is a channel matrix between the transmitting node 100 and the relay node 200,

Is zero and the covariance matrix is

Is a complex white Gaussian noise vector.

의해 프리 코딩(precoding)되어 수신 노드(300)에서의 수신 신호

는 수학식 4와 같다. In the second time slot considering the transmission between the relay node 200 and the reception node 300, the reception signal of the relay node 200 is transmitted through a filter of a relay node (hereinafter referred to as a relay filter)

And the received signal at the receiving node 300

Is expressed by Equation (4).

는 중계 노드(200)와 수신 노드(300) 사이의 채널 매트릭스이며,

는 평균이 0이고, 공분산 매트릭스가

인 복소 백색 가우시안 노이즈 벡터이다. 또한, 중계 필터는 중계 노드(200)의 파워

조건을 만족한다.here

Is a channel matrix between the relay node 200 and the receiving node 300,

Is 0 and the covariance matrix is

Is a complex white Gaussian noise vector. In addition, the relay filter is a function of the power of the relay node 200

Condition.

가 feedforward 매트릭스

을 통과한 신호를

로 얻을 수 있다. 그리고 대각 요소들이 모두 0인 feedback 매트릭스

을 사용한다. 검출과정은

부터

까지 순차적으로 이루어지며, 검출된 신호는 송신 신호(x)와 동일하다고 가정할 수 있다(즉,

). 그러면 검출된 신호는 수학식 5와 같이 나타낼 수 있다. In the receiving node 300, a nonlinear detection feedback receiver 310 is applied to sequentially detect transmitted signals. As can be seen in Figure 1,

Feedforward matrix

The signal passed through

. And a feedback matrix of all 0 diagonal elements

Lt; / RTI > The detection process

from

, And it can be assumed that the detected signal is the same as the transmitted signal x (that is,

). Then, the detected signal can be expressed by Equation (5).

For MSE (Mean Squared Error), the error vector can be defined as shown in Equation (6).

와

이다. 그러면 오류 공분산 매트릭스

는 수학식 7과 같이 계산할 수 있다.here

Wow

to be. The error covariance matrix

Can be calculated as shown in Equation (7).

이다. 또한, 각 채널 링크 사이의 Signal-to-Noise-Ratio (SNR)는 각각

와

로 정의하였다. here

to be. Also, the Signal-to-Noise-Ratio (SNR) between each channel link is

Wow

Respectively.

는 수학식 8과 같이 구해질 수 있다.In the presence of the detection feedback receiver 310,

Can be obtained as shown in Equation (8).

를 수학식 9로 표현될 수 있다.Applying the result of Equation (8) to Equation (7), the error covariance matrix

Can be expressed by Equation (9).

는 대각 요소들이 모두 1인 feedback 매트릭스이다. 수학식 9의 결과를 이용하면, MSE를 최적화하는 문제는 수학식 10과 같이 표현될 수 있다.here

Is a feedback matrix with all 1 diagonal elements. Using the results of Equation (9), the problem of optimizing the MSE can be expressed as Equation (10).

However, Equation (10) is difficult to obtain a transmission / reception relay filter having non-convex and closed-form. Therefore, Equation 10 can be simply expressed using the following Theorem.

Theorem 1:

의 형태로 나타낼 수 있고, 이를 이용하여 에러 공분산 매트릭스 수학식 9는 수학식 11과 같이 표현될 수 있다. 여기서 B는 중계 송신 필터를 의미하고, L_r은 중계 수신 필터를 의미한다.The relay transmit / receive filter

, And using this, the error covariance matrix equation (9) can be expressed as shown in Equation (11). Where B denotes a relay transmission filter, and L _r denotes a relay reception filter.

은 상기 송신 노드(100)와 상기 중계 노드(200) 사이의 에러 공분산이고,

는 상기 중계 노드(200)와 수신 노드(300) 사이의 에러 공분산이다. 또한,

와

은 각각

와

로 구해진다. 그리고

으로 주어지고,

은

의 공분산 매트릭스이다. here

Is an error covariance between the transmitting node (100) and the relay node (200)

Is an error covariance between the relay node 200 and the receiving node 300. Also,

Wow

Respectively

Wow

. And

Lt; / RTI >

silver

Is the covariance matrix.

Using Equation (11), Equation (10) can be made as Equation (12).

으로 인해 여전히 non-convex이다. 따라서 본 발명의 일실시예에서는 이러한 문제점을 해결하기 위해 송신 노드 기반 프리 코딩 방식 및 중계 노드 기반 프리 코딩 방식의 두 가지 경우로 필터를 산출할 수 있다. 송신 노드 기반 프리 코딩 방식은 송신 노드(100)와 중계 노드(200) 에러 공분산이 최소화되도록 필터를 우선적으로 산출하는 방식을 의미하고, 중계 노드 기반 프리 코딩 방식은 중계 노드(200)와 수신 노드(300) 사이의 에러 공분산이 최소화되도록 필터를 우선적으로 산출하는 방식을 의미한다. 즉, 송신 노드 기반 프리 코딩 방식은 첫 번째 타임 슬롯에서의 채널 환경에 의한 에러를 우선적으로 고려한 방식이고, 중계 노드 기반 프리 코딩 방식은 두 번째 타임 슬롯에서의 채널 환경에 의한 에러를 우선적으로 고려한 방식이다. Equation 12 also shows the feedback matrix

It is still non-convex. Therefore, in an embodiment of the present invention, in order to solve such a problem, a filter can be calculated in two cases: a transmission node-based precoding method and a relay node-based precoding method. The transmitting node-based precoding scheme refers to a method of preferentially calculating a filter so that error covariance between the transmitting node 100 and the relay node 200 is minimized, and the relay node- 300) is minimized to a minimum. That is, the transmission node-based precoding scheme takes priority into consideration of error caused by the channel environment in the first time slot, and the relay node-based precoding scheme takes into account the error caused by the channel environment in the second time slot to be.

2 is a flow diagram illustrating a wireless signal processing method in a wireless communication system environment with a detection feedback receiver in accordance with an embodiment of the present invention. That is, FIG. 2 shows a method of calculating the transmission filter and the relay filter using the above-described two methods in the signal processing device 400.

와

에 singular value decomposition (SVD)는 수학식 13과 같다.Before looking at the filter calculation method of the above two cases,

Wow

The singular value decomposition (SVD) is expressed by Equation (13).

,

,

,

는 unitary 매트릭스이며,

와

는 singular 값들을 가지는 대각 매트릭스이다. 또한

,

,

,

, 는 각각의 unitary 매트릭스에서 처음부터

행들의 값을 가지는 매트릭스로 정의한다. here

,

,

,

Is a unitary matrix,

Wow

Is a diagonal matrix with singular values. Also

,

,

,

, From the beginning in each unitary matrix

Define this as a matrix with the values of the rows.

The signal processing apparatus 400 may calculate a first filter value set according to a transmission node-based precoding method (S210). The set of filter values may include a relay filter value and a transmit filter value, and a detected feedback filter value.

3 is a flowchart showing a method of setting a filter value by a transmission node-based precoding method in the radio signal processing method of FIG.

을 최소화 하는 문제를 수학식 14와 같이 만들 수 있다.First, the signal processing apparatus 400 detects a first filter value of the transmitting node and a second filter covariance value of the transmitting node 100 such that the error covariance between the transmitting node 100 and the relay node 200 has a minimum value (referred to as 'first error covariance' The feedback first filter value may be calculated (S310). That is, in Equation 12,

Can be minimized by Equation (14).

The optimum transmission filter of Equation (14) (i.e., the first filter value of the transmitting node) has the form of Equation (15).

이고, 각각의 값들은 water-filling과 비슷한 수학식 16과 같은 해들로 구할 수 있다.here,

, And each value can be found in the same manner as equation (16), similar to water-filling.

와

는 수학식 17의 geometric mean decomposition (GMD) 결과를 이용하여 구할 수 있다.And

Wow

Can be obtained by using the geometric mean decomposition (GMD) result of Equation (17).

이고,

을 이용하여

을 구한다. In the above formula

ego,

Using

.

와

를 이용하여

를 구하는 것이다. 수학식 12에서

을 최소화 하는 문제는 수학식 18과 같다.The transmission filter value and the detection feedback filter value are applied to the relay node 200 and the relay node 200 so that the relay covariance value between the relay node 200 and the receiver node 300 is minimized so that the error covariance More precisely, the relay transmission filter value B) can be calculated (S320). That is, in step S320,

Wow

Using

. In Equation 12,

Is minimized by Equation (18).

를 구할 수 있다.Solving equation (18), equation

Can be obtained.

는

의 SVD 결과에 오른쪽 unitary 매트릭스이다. 또한,

는

같이 나타낼 수 있고 여기서

는

의 eigen 값들을 이용하여 구할 수 있다. 위와 같이 수학식 12를 걸쳐 해결함으로써 closed-form을 가진 송/수신, 중계 필터를 구할 수 있다.In equation (19)

The

The SVD result is the right unitary matrix. Also,

The

Can be represented as

The

Can be obtained by using the eigenvalues of Eq. By solving Equation (12) above, it is possible to obtain a transmission / reception relay filter having a closed-form.

Next, the signal processing apparatus 400 may calculate a second set of filter values using a relay node-based precoding method (S220). The set of filter values may include a relay filter value and a transmit filter value, and a detected feedback filter value.

4 is a flowchart showing a method of setting a filter value by a relay node-based precoding method in the radio signal processing method of FIG.

First, the signal processing apparatus 400 may calculate a second filter value and a detection feedback second filter value of the relay node so that the second error covariance has a minimum value (S410).

In operation S420, the second filter value of the transmitting node may be calculated so that the first error covariance has a minimum value by applying a second filter value and a detection feedback second filter value of the relay node. The process of calculating the specific filter value is similar to that of FIG. 3 and will not be described here.

Finally, since the error performance depends on the hop channel having the higher MSE value among the two hop channels, depending on the system environment, a filter value set having better performance among the above two filter design schemes is selected in the following manner .

와

의 두 가지 모두 필요로 하게 된다. 하지만 송신 노드 기반 프리 코딩 방식과 중계 노드 기반 프리 코딩 방식은 각각의 노드에 인접한 채널 정보만을 필요로 하므로 요구되는 채널 정보량에서 이득이 있다. 따라서 최종적인 선택방법은 추가적인 채널 정보를 이용함으로써 각각의 송신 노드 기반 프리 코딩 방식과 중계 노드 기반 프리 코딩 방식에 비해 향상된 BER(Bit Error Rate) 성능을 나타낸다는 것을 시뮬레이션 결과를 통해 알 수 있다.Equation (20) represents the final selection of filter solutions (i.e., a set of filter values) corresponding to the MSE having a smaller MSE by comparing the MSE of the transmission node-based precoding with the MSE of the relay node-based precoding (S230, S240). In the selection method as described above, channel information

Wow

Both of which are required. However, the transmission node based precoding method and the relay node based precoding method require only the channel information adjacent to each node, so that there is a gain in the required channel information amount. Therefore, it can be seen from the simulation result that the final selection method exhibits improved BER (Bit Error Rate) performance compared with the respective transmission node based precoding method and the relay node based precoding method by using additional channel information.

5 to 6 are diagrams comparing the performance of the wireless processing method and other signal processing methods related to the present embodiment.

에 대해 BER 성능을 나타낸 그래프이다. Optimal-DFE는 기존의 반복적 접근방법을 통해 중계 필터를 설계한 기법이고, Optimal-Linear는 수신기가 비선형 DFE 대신 선형 수신기를 가졌을 때 최적 필터를 설계한 기법이다. 그래프를 통해 선형 수신기를 사용하는 것보다 DFE 비선형 수신기를 쓰는 것이 월등한 성능 향상을 가진다는 것을 알 수 있다. 또한, 제안된 기법(본 발명의 일실시예에 의한 기법)을 종래의 DFE 수신기를 가진 최적 기법과 비교하였을 때 BER 성능 열화가 미미하다는 것을 알 수 있다. 따라서 본 발명의 일실시예에서 제안된 필터 설계 기법이 기존의 반복적 접근 방식에 비해 상당한 복잡도를 줄였음에도 불구하고 기존 기법의 BER 성능에 근접하는 효율적인 기법이라는 것을 알 수 있다.Figure 5

And the BER performance is shown in FIG. Optimal-DFE is a technique for designing a relay filter through a conventional iterative approach. Optimal-Linear is a technique for designing an optimal filter when a receiver has a linear receiver instead of a nonlinear DFE. It can be seen that using a DFE nonlinear receiver has a better performance gain than using a linear receiver over the graph. In addition, it can be seen that the BER performance degradation is insignificant when the proposed technique (the technique according to an embodiment of the present invention) is compared with an optimal technique having a conventional DFE receiver. Therefore, it can be seen that the proposed filter design scheme is an efficient technique that approaches the BER performance of the existing scheme despite the reduced complexity compared to the conventional iterative approach.

6 is a graph illustrating BER performance when the number of antennas is 3 at the node end. It can be seen that the BER performance is almost the same between the transmission node based precoding method (SP case) and the relay node based precoding method (RP case) according to an embodiment of the present invention. It can be seen that the technique of selecting a filter with a small MSE has a slightly better BER performance.

As described above, the radio signal processing method according to an embodiment of the present invention can reduce the complexity in filter design while minimizing errors.

The above-described wireless signal processing method may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable recording medium. At this time, the computer-readable recording medium may include program commands, data files, data structures, and the like, alone or in combination. On the other hand, the program instructions recorded on the recording medium may be those specially designed and configured for the present invention or may be available to those skilled in the art of computer software.

The computer-readable recording medium includes a magnetic recording medium such as a magnetic medium such as a hard disk, a floppy disk and a magnetic tape, an optical medium such as a CD-ROM and a DVD, a magnetic disk such as a floppy disk, A magneto-optical media, and a hardware device specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like.

The recording medium may be a transmission medium, such as a light or metal line, a wave guide, or the like, including a carrier wave for transmitting a signal designating a program command, a data structure, and the like.

The program instructions also include machine language code, such as those generated by the compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

The above-described wireless signal processing method is not limited to the configuration and method of the above-described embodiments, but the embodiments may be modified such that all or some of the embodiments are selectively combined .

100: transmitting node
200: relay node
300: receiving node
310: detection feedback receiver

Claims (5)

A method for processing a wireless signal in a wireless communication environment in which a relay node is present and a detected feedback receiver is present,
Calculating a first set of filter values in a transmission node-based precoding scheme that is a method of preferentially calculating a filter such that an error covariance between a transmitting node and a relay node has a minimum value, said first set of filter values comprising a first A filter value and a first filter value of a transmitting node;
Calculating a second set of filter values using a relay node based precoding scheme that is a method of preferentially calculating a filter such that the error covariance between the relay node and the receiving node has a minimum value, 2 filter value and a second filter value of the transmitting node; And
Selecting one of the first set of filter values and the second set of filter values to determine a final set of filter values. ≪ RTI ID = 0.0 > 31. < / RTI > 2. The method of claim 1, wherein the final filter value set step
Determining a set of filter values having a smaller error value as a final filter value set, either when applying the first set of filter values or when applying the second set of filter values. ≪ RTI ID = 0.0 > A method for processing a wireless signal in a communication environment. 3. The method of claim 2,
Wherein the error value is represented by a sum of a first error covariance and a second error covariance,
Wherein the first error covariance is an error covariance between the transmitting node and the relay node and the second error covariance is an error covariance between the relay node and the receiving node. Signal processing method. 4. The method of claim 3, wherein the first filter value set calculation step
Calculating a first filter value and a detection feedback first filter value of the transmitting node such that the first error covariance has a minimum value; And
And calculating a first filter value of the relay node by applying the first filter value and the detection feedback first filter value of the calculated transmission node so that the second error covariance has a minimum value. A method for processing a wireless signal in a wireless communication environment. 4. The method of claim 3, wherein the second filter value set calculation step
Calculating a second filter value and a detection feedback second filter value of the relay node such that the second error covariance has a minimum value; And
And calculating a second filter value of the transmitting node so that the first error covariance has a minimum value by applying a second filter value and a detection feedback second filter value of the calculated relay node, A method for processing a wireless signal in a wireless communication environment with a receiver.

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