KR100603605B1 - Method for Interference Cancellation using Overlap Technique in Mobile Communication System - Google Patents

Abstract

The present invention relates to a method for eliminating interference in a mobile communication system using a redundancy detection method and a computer readable recording medium storing a program for realizing the method. The interference cancellation method of the mobile communication system using the overlap detection method for reducing the amount of calculation of the joint detection operation without degrading the reception performance of the present invention comprises: a first step of overlapping received data; And a second step of detecting only symbols that are not affected by interference, wherein the size of the overlapped portion is determined by a maximum time delay. According to the present invention, by using a symbol affected by interference in the joint detection process, by completely removing the interference component of the unconsidered symbol, there is an effect of greatly reducing the amount of calculation of the joint detection operation without deterioration in reception performance. .

TD-CDMA, Joint Detection, Decomposition, Redundant Detection, Interference Rejection

Description

Method for Interference Cancellation using Overlap Technique in Mobile Communication System}             

1 is a timing diagram of a data transmission signal of a typical TD-CDMA system;

2 is a structural diagram of an unlicensed linear block equalizer of a TD-CDMA system to which the present invention is applied;

3 is a structural diagram of an unlicensed block decision feedback equalizer of a TD-CDMA system to which the present invention is applied;

4a and 4b is an exemplary view for explaining an approximate decomposition method to which the present invention is applied,

5 is a timing diagram for explaining the effect of interference due to time delay components when the number of symbols considered in the joint detection process is reduced;

6 is a timing diagram illustrating an interference cancellation method of a mobile communication system using a redundant detection method according to the present invention.

* Explanation of symbols for main parts of the drawings

210: whitening matching filter 220: whitening filter

230: ISI / MAI Eliminator 310: Limiter

320: feedback

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for canceling interference in a mobile communication system using a redundancy detection method and a computer-readable recording medium recording a program for realizing the method, and more particularly, to time division code division multiple access. The present invention relates to an interference cancellation method of a mobile communication system using a redundancy detection method used in a mobile communication system, and a computer-readable recording medium recording a program for realizing the method.

1 is a timing diagram of a data transmission signal of a typical TD-CDMA system.

, 확산 계수가

일 때,

개의 칩으로 구성된 2개의 데이터 블록과

개의 칩 길이를 가지는 미드엠블 부분으로 이루어진다. As shown in the figure, a signal transmitted in a TD-CDMA system has a number of symbols.

Diffusion coefficient

when,

2 data blocks of 4 chips

And a midamble portion having four chip lengths.

The transmitted signal is received in combination with the time delayed components over the multipath channel.

The midamble portion of the received signal is used for channel estimation, and the data blocks are detected after the time delay component of the midamble is removed.

In general, a redundant detection method such as FIG. 2 or 3 may be used to detect such data.

2 is a structural diagram of a zero forcing linear block equalizer of a TD-CDMA system to which the present invention is applied.

은 수신 벡터를 나타내며,

는 추정된 전송 심벌 벡터를 의미한다. 또한,

는 채널 정보와 코드 정보를 포함하는 시스템 행렬이며,

은 잡음의 상관 행렬이다. 행렬 상단의

연산은 'Hermitian' 연산을 의미한다. As shown in the figure, in an unlicensed linear block equalizer,

Represents the receive vector,

Denotes the estimated transmission symbol vector. Also,

Is a system matrix containing channel information and code information.

Is the correlation matrix of noise. At the top of the matrix

Operation means 'Hermitian' operation.

The unlicensed linear block equalization apparatus to which the present invention is applied includes a whitening matched filter 210, a whitening filter 220, and an ISI (intersymbol interference signal) / MAI (multi-access interference signal) canceller 230.

A typical receiver is implemented with a matched filter, which typically extends the typical receiver to a pre-whitening filter for the case of correlated noise. This general receiver is defined as a Whitening Matched Filter 210.

The whitening filter 220 reproduces an intersymbol interference signal and a multiple access interference signal.

In addition, the ISI / MAI remover 230 removes the intersymbol interference signal and the multiple access interference signal from the received signal.

을 최소화시킴으로써 요구되는 신호와 잡음만을 포함하고 있는 심벌

에 관한 추정값을 얻을 수 있다. The unlicensed linear block equalizer of FIG. 2 is the 'Euclidean norm' of the error.

Symbols containing only the signal and noise required by minimizing

Obtain an estimate for.

는 다음의 수학식 1과 같이 표현될 수 있다.

May be expressed as Equation 1 below.

로 정리된다. In this case, by 'Cholesky decomposition'

It is cleaned up.

3 is a structural diagram of an unlicensed block decision feedback equalizer of a TD-CDMA system to which the present invention is applied.

As shown in the figure, the unlicensed block decision feedback equalizer to which the present invention is applied is composed of a whitening matching filter 210, a whitening filter 220, a limiter 310, and a feedbacker 320.

Unlike the unlicensed linear block equalizer of FIG. 2 configured as the ISI / MAI eliminator 230, the unlicensed block decision feedback equalizer of FIG. 3 includes a limiter 310 and a feedback unit 320, thereby receiving a received signal. The feedback function removes the intersymbol interference signal and the multiple access signal.

The unlicensed block decision feedback equalizer of FIG. 3 receives a signal represented by Equation 2 below.

If detection is performed while removing the signal determined by the decision feedback, the following equation (3) is arranged.

In this case, since the process of removing the determined signal is included, a 'power ordering' process is needed to remove the reliable signal first.

의 연산으로 수행된다. 특히,

의 '분해(Decomposition)' 연산은 매우 큰 계산량을 가지므로, 분해 과정의 계산량을 줄이는 과정이 핵심이 된다. The joint detection process includes a matrix including both channel information and code information of all symbols of all users.

Is performed by the operation of. Especially,

The 'decomposition' operation of has a very large amount of computation, so the process of reducing the computation of the decomposition process is the key.

는 '토플리츠(Toeplitz)' 구조를 갖는다. 이 때,

은 '토플리츠' 구조는 아니지만, 이에 근접한 구조를 가지게 된다. 그러므로, 일반적으로 정보를 포함하는 상위 몇 행만 계산하고, 나머지 부분은 계산된 부분을 복사해 넣는 근사 분해 방식으로 계산량을 줄이는 연구가 수행되어 왔다.Meanwhile, the matrix

Has a 'Toeplitz' structure. At this time,

Is not a 'toplit' structure, but has a structure close to this. Therefore, research has been conducted to reduce the amount of computation in general by approximating decomposition, in which only the top few rows containing information are calculated and the remaining parts are copied.

4A and 4B are exemplary views for explaining an approximation decomposition method to which the present invention is applied.

As shown in the figure, the approximate decomposition scheme to which the present invention is applied is a portion labeled 'calculation' is a portion that is actually calculated during the decomposition process, and the 'copy' portion is a portion having substantially the same value as the calculated portion. , Copying and filling in the calculated values.

는 사용자 수,

은 심벌 수,

는 실제로 계산된 행의 수를 의미한다. At this time,

Is the number of users,

Silver symbol number,

Is the number of rows actually calculated.

As such, the amount of computation in the 'decomposition' process increases greatly as the number of users and the number of symbols considered increase.

In the TD-CDMA system, if the channel estimation using the midamble is performed, the channel information for all symbols of the same user is constant in one time slot. This can greatly reduce the amount of computation.

Also, since the system matrix does not need to be regenerated in one time slot, the decomposition process only needs to be performed once.

However, if the overlap detection process is performed by reducing the number of symbols to be considered, there is a problem that the time delay components of the front and back symbols which are not considered in the reception vector act as interference in a channel environment with a large maximum time delay. Since there is no method of properly removing the interference components, the reception performance is very poor.

The present invention has been proposed to solve the above problems of the prior art, by using the symbols affected by the interference in the joint detection process, by completely removing the interference components of the unconsidered symbol, deterioration in reception performance An object of the present invention is to provide an interference cancellation method of a mobile communication system using a redundant detection method for preventing the error.

In addition, the present invention uses a symbol affected by the interference in the junction detection process, but by completely removing the interference component of the unconsidered symbol, by reading a computer for recording a program for realizing a function for preventing the degradation of reception performance Another purpose is to provide a record carrier.

According to an aspect of the present invention, there is provided a method for eliminating interference in a mobile communication system using a redundant detection method for reducing the amount of calculation of a joint detection operation without deteriorating reception performance, the method comprising: overlapping received data; And a second step of detecting only symbols that are not affected by the interference, wherein the size of the overlapped portion is determined by a maximum time delay. .

In addition, the present invention provides a first function of overlapping received data in a device having a microprocessor in order to provide a method for canceling interference in a mobile communication system using a redundancy detection method for reducing the amount of calculation of the joint detection operation without degrading the reception performance. ; And a second function of detecting only symbols that are not affected by interference, wherein the size of the overlapping portion provides a computer readable recording medium having recorded thereon a program for realizing that the size of the overlapping portion is determined by a maximum time delay.

In the present invention, since the symbols affected by the interference have low reliability, the signal is not determined during the detection process. Then, the overlap detection process is performed so as not to be affected by the interference in the next junction detection process.

This redundant detection method can significantly reduce the computation amount without degrading the reception performance.

In addition, the present invention can be combined with the existing approximation (approximate) technique it is possible to reduce the amount of computation more efficiently.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same components have the same number as much as possible even if displayed on different drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 5 is a timing diagram illustrating the influence of interference due to time delay components when the number of symbols considered in the joint detection process is reduced.

은 고려하는 심벌의 수를 의미하며,

보다는 작은 값을 갖는다. 전송된 신호는

의 길이를 갖지만, 시간 지연에 의해 수신된 벡터는

의 길이를 가지며, 이때

는 최대 시간 지연을 의미한다.As shown in the drawings,

Means the number of symbols to consider,

Has a smaller value. The transmitted signal is

Has a length of, but the vector received by the time delay

Has a length of, where

Means the maximum time delay.

연산은

번 연산을 해주어야 한다. As already explained, reducing the number of symbols under consideration can reduce the size of the matrix without losing information in the system matrix. However, once in the data block

Operation

You have to do it twice.

Since this operation is not so large compared to the decomposition process, the complexity of the entire system can be greatly reduced.

However, as long as the size of the symbol to be considered is simply reduced, as shown in FIG. 5, the received signal sequence is interrupted by the time delay component of the front and back symbols. This interference component is more affected as the time delay of the channel increases, and since there is no way to properly remove the interference, the reception performance is degraded.

6 is a timing diagram illustrating an interference cancellation method of a mobile communication system using a redundant detection method according to the present invention.

라고 정의하기로 한다.As shown in the figure, the interference cancellation method of the present invention can detect only symbols that are not affected by the interference by overlapping the received data vector. In this case, the number of duplicate symbols

Let's define.

In the interference cancellation method according to the present invention, the received data vector is overlapped to detect only symbols that are not affected by the interference. In this case, the size of the overlapped portion is affected by the maximum time delay.

가 되며,

는 최소한

보다는 커야 한다. 단, 한 데이터 블록에서 가장 앞과 가장 마지막 연산은 지연된 심벌에 의한 간섭을 절반만 받으므로 검출하는 심벌 수는

가 된다. The number of symbols detected in the junction detection process once

Becomes

At least

Should be greater than However, since the earliest and last operation in one data block receives only half of the interference caused by delayed symbols, the number of symbols to be detected is

Becomes

If there is a large gap between one symbol and another, there is no correlation between the two symbols. Therefore, the number of symbols under consideration does not significantly affect the performance when a certain size is exceeded.

Therefore, it is important to find the number of symbols to be considered and the size of symbols to be duplicated, which can reduce the calculation amount as much as possible without degrading performance.

These factors can be easily determined by knowing the time delay information of the channel. Using the redundancy technique, the computation of the junction detection process can be greatly reduced without compromising performance due to the effects of time delay component interference.

의 계산량을 가지게 된다. 여기에 근사 기법을 적용하면

으로 계산량을 줄일 수 있다. In general, 'Cholesky decomposition'

It has a calculation amount of. If you apply an approximation here

This can reduce the amount of computation.

을

으로 줄이므로,

의 계산량을 가지게 되며, 이 때 근사 기법도 결합할 수 있으므로,

까지 계산량을 낮출 수 있다. The overlap detection method according to the present invention

of

Is reduced to

And the approximation technique can be combined,

The calculation can be lowered to.

의 이득을 얻을 수 있다. By using the redundancy detection method of the present invention, in terms of 'decomposition' calculation amount without degrading performance

The gain can be obtained.

의 연산 과정 횟수가 증가하긴 하지만, 이 경우에도

행렬의 크기 자체가 작아지기 때문에 계산량의 증가는 없음을 알 수 있다.

Although the number of operations in increases,

As the size of the matrix itself becomes smaller, it can be seen that there is no increase in the amount of computation.

The method of the present invention as described above may be implemented as a program and stored in a computer-readable recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.).

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited to the drawing.

The present invention as described above, by using a symbol affected by the interference in the junction detection process, by completely removing the interference component of the unconsidered symbol, it is possible to greatly reduce the amount of calculation of the joint detection operation without deteriorating the reception performance There is.                     

Furthermore, the present invention has the effect of enabling efficient data communication by preventing degradation of reception performance.

Claims (4)

In a mobile communication system using a topless-block structure as a modeling method of a system matrix for joint detection, in the interference cancellation method using a joint detection method for reducing the amount of calculation of the joint detection operation without deteriorating reception performance, Duplicating received data; Detecting only the symbols that are not affected by the interference by reducing the amount of calculation of the junction detection process by determining the number of overlapping symbols in consideration of the maximum time delay of the size of the overlapping portion; And And applying an approximation technique by using a symbol that is not affected by the detected interference. The method of claim 1, The number of symbols detected by junction detection is

(only,

Is the number of symbols to consider,

Is the number of duplicate symbols)

Is

(only,

Is the maximum time delay,

Is a diffusion coefficient) An interference cancellation method of a mobile communication system using a redundant detection method characterized in that. The method of claim 1, The number of symbols detected by junction detection for the front part and the back part of the data block of the received data is

Thing An interference cancellation method of a mobile communication system using a redundant detection method characterized in that. delete

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