KR100598044B1 - Apparatus for detecting multiuser and method thereof - Google Patents

Abstract

The multi-user detection apparatus and method of the present invention applies a switching technique to use a matched filter method when the background noise or a large amount of calculation is large, and a decorrelator method when the user interference signal is large, so that It is an object of the present invention to provide a multi-user detection apparatus and method that can reduce the amount of computation while reducing the bit error rate.

In order to achieve the above object, the apparatus of the present invention, a multi-user detection device, the switching unit for transmitting at least one user data input from the outside by the switching control of the control unit to any one of the matching filter unit or the decorrelating unit; The matching filter unit matching at least one user data input from the switching unit using a correlation to output the result data as result data; The decorrelating unit for matching at least one user data input from the switching unit using a correlation and applying an inverse correlation coefficient to output the result data as result data; And determining an interference signal determination value through a correlation coefficient and user data amplitude of the result data processed by either the matching filter unit or the decorrelating unit, and if the determined interference signal determination value is smaller than the result data, an external user. And a control unit for controlling the switching unit to transmit data to the matching filter unit, and controlling the switching unit to transmit external user data to the decorrelator unit when the determined interference signal determination value is larger than the result data.

Multi-user, decorrelation, matched filter

Description

Multi-user detection apparatus and method {APPARATUS FOR DETECTING MULTIUSER AND METHOD THEREOF}             

1 is a block diagram illustrating a simple matched filter receiver with k users;

2 is a block diagram showing a receiver using a conventional decorrelator;

3 is a block diagram showing a multi-user detection apparatus according to an embodiment of the present invention;

Figure 4 is a flow chart showing a multi-user detection method according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

310: switching unit 320: matching filter unit

330: decorrelating unit 340: control unit

350: data symbol determination unit

The present invention relates to a multiuser detection apparatus and method, and more particularly, to a multiuser detection apparatus and method for demodulating data of a desired user in a synchronous communication environment in which a plurality of users exist.

As a conventional CDMA detection device, a matched filter detection device, an optimum multi-user detection device, a correlation cancellation detection device, a parallel interference detection device, and the like have been proposed.

For convenience of explanation, the description is made by adopting a symbol synchronous and additive white Gaussian noise (AWGN) channel model between users. Thus, the elements of the amplitude matrix are all real and positive. A typical CDMA channel is symbol asynchronous, where symbol delay between users occurs arbitrarily, and the amplitude matrix has complex elements. However, for convenience of explanation, a real model is adopted.

First, a matched filter detection device will be described below.

The output of the matched filter detection device of user k in K multi-user channels may be expressed as the following equation in matrix form.

The k-th row of the matrix according to Equation 1 is as follows.

Here, h is an amplitude representing the magnitude of the user signal, d is data of the user signals, γ is a correlation value, and n is background noise.

Then, the symbol decision value is given by the following equation.

Figure 1 shows the structure of a simple matched filter receiver with k users.

The conventional matched filter receiver includes: a plurality of matched filter detectors 111 to 113 for receiving a user signal and outputting a matched result using correlation; And a plurality of symbol determiners 121 to 123 having output values of the matched filter detectors 111 to 113 and determining the value as -1 or 1 according to a predetermined threshold value 0.

As shown in Equation 2, such a matched filter receiver produces a result of the value of the second term (an interference signal of another user) acting as an interference signal to the value of the first term. Therefore, no matter how small the background noise n _k of the channel is, the performance of the receiver is affected by the interference signal caused by the presence of multiple users. It is easy to see that the value of the second term depends a lot on the correlation value γ between user codes. The smaller the correlation value between different user codes, the smaller the second term of Equation 2, which is a multi-user interference signal, and thus shows good performance. However, even if a code having a small correlation value is selected, the interference signal increases as the number of users increases, so that the performance of the matched filter receiver becomes worse. The smaller the size of the user has a problem that the interference signal is larger.

As described above, the matched filter detector has been adopted as a receiver of most CDMA systems that have been operated so far due to its simple structure, but it is a classic matched filter receiver in a next generation mobile communication system that requires more subscribers and requires higher quality service. This problem must be improved. Therefore, in order to improve the problem of the matched filter receiver, a technique of using a decorrelator as a multi-user detector has been studied.

FIG. 2 is a block diagram illustrating a receiver using a conventional decorrelator. The conventional receiver includes a plurality of matched filter detectors 211 that receive a user signal and output a matched result using correlation. 213); An inverse correlation unit 220 that applies an inverse correlation coefficient to the plurality of matched filter detection units 211 to 213; And a plurality of symbol determination units 231 to 233 having an output value of the decorrelator 220 and determining a value of -1 or 1 according to a predetermined threshold value 0.

Here, the above-described output value of the decorrelator 220 is a matrix value and is represented by the following equation.

)을 증가시키기 때문에, 다른 사용자의 간섭 신호는 작고 배경 잡음은 큰 경우 오히려 정합필터 검출기보다 성능이 떨어지는 문제점이 있다.Here, the inverse matrix of the correlation matrix R is obtained and multiplied by the outputs of the plurality of matched filter detectors 211 to 213. This technique requires much more computational quantity than the present, and the computational quantity as the number of users increases. There is a problem that increases exponentially. In addition, the signal processing using a decorrelator is the background noise (

Since the interference signal of the other user is small and the background noise is large, the performance is lower than that of the matching filter detector.

The present invention devised to solve the above problems, by applying a switching technique, using a matching filter method in the case of a large background noise or a large amount of calculation, and using a decorrelator method in the case of a large user interference signal, It is an object of the present invention to provide a multi-user detection apparatus and method that can reduce the amount of computation at the same time to reduce the bit error rate.

In order to achieve the above object, the apparatus of the present invention, a multi-user detection device, the switching unit for transmitting at least one user data input from the outside by the switching control of the control unit to any one of the matching filter unit or the decorrelating unit; The matching filter unit matching at least one user data input from the switching unit using a correlation to output the result data as result data; The decorrelating unit for matching at least one user data input from the switching unit using a correlation and applying an inverse correlation coefficient to output the result data as result data; And determining an interference signal determination value through a correlation coefficient and user data amplitude of the result data processed by either the matching filter unit or the decorrelating unit, and if the determined interference signal determination value is smaller than the result data, an external user. And a control unit for controlling the switching unit to transmit data to the matching filter unit, and controlling the switching unit to transmit external user data to the decorrelator unit when the determined interference signal determination value is larger than the result data.

On the other hand, in order to achieve the above object, the method of the present invention, in the multi-user detection method, by processing at least one user data input from the outside using any one of the matching filter unit use mode or the decorrelating unit use mode. A result data calculating step of calculating result data; An interference signal determination value determining step of determining an interference signal determination value through a correlation coefficient for the calculated result data and a user data amplitude; A comparison step of comparing the determined interference signal determination value with the calculated result data; And a use mode activation step of activating the matching filter unit using mode if the interference signal determination value is smaller than the result data, and activating the decorrelator using mode if the interference signal determination value is larger than the result data.

Hereinafter, the most preferred embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily implement the technical idea of the present invention. .

First, Figure 3 is a block diagram showing a multi-user detection device according to an embodiment of the present invention, the multi-user detection device of the present invention, the switching unit 310, matching filter unit 320, the decorrelating unit 330 ), A controller 340, and a data symbol determiner 350.

The switching unit 310 receives user data and plays a role of switching the path of the user data according to a switching signal.

In addition, the matching filter unit 320, when receiving the user data from the switching unit 310, serves to output the matched result data using a correlation.

On the other hand, the decorrelator 330, upon receiving the user data from the switching unit 310, generates a matched result value using a correlation, and applies the result data applied by applying a correlation coefficient to the result value. It plays a role of outputting.

)보다

가 큰 경우에는 상기 정합 필터부(320)로 도통시키도록 하는 상기 스위칭 신호를 생성하고, 상기 간섭 신호 판정 값(

)보다

가 크지 않은 경우에는 상기 역상관부(330)로 도통시키도록 하는 상기 스위칭 신호를 생성하는 역할을 한다. 여기서, 앞서 종래 기술을 통해 전술한 바와 같이 y_k는 본 발명의 제어부(340)의 스위칭 제어에 의해 정합 필터부(320) 또는 역상관부(330) 중 어느 하나에서 사용자 데이터가 처리되어져 출력되는 결과 데이터를 말하며, [수학식 1] 내지 [수학식 4]에 기재된 바와 같이 배경잡음 n이 섞여 있다.In addition, the control unit 340 may determine an interference signal determination value (

)see

If is large, generate the switching signal for conducting to the matched filter unit 320, and the interference signal determination value (

)see

If not large, it serves to generate the switching signal for conducting to the decorrelator 330. Here, as described above through the prior art y _k is a result of the user data is processed and output from any one of the matching filter unit 320 or the decorrelator 330 by the switching control of the controller 340 of the present invention. It refers to data, and background noise n is mixed as described in [Equation 1] to [Equation 4].

Here, h is an amplitude representing the magnitude of the user signal, γ is a correlation value, and α is a value greater than zero (0) and less than one (1), and may be adjusted according to background noise and calculation amount. For example, when the background noise is large or the amount of calculation is too large, the value of α is adjusted close to zero so that the matching filter unit 320 is used more. Otherwise, the value of α is one (1). Close to) so that the decorrelator 330 can be used frequently. In addition, referring to the conventional technology described above, when the background noise is too large, since the user data processing performance using the decorrelator is poor, a matching filter unit is generally used, and when the interference signal between the user data is too large, matching is performed. In general, the decorrelation unit is used because the performance of the user data processing using the filter unit is poor. On the other hand, since the inverse matrix calculation, a plurality of multiplication operations, etc. must be performed in processing the user data using the decorrelator, the amount of computation is increased, and thus, the terminal resources are consumed considerably, and the terminal available resources are often insufficient. Here, the maximum background noise that can be processed by the decorrelator is referred to as a decorrelative processable threshold, and resources required for processing user data, particularly resources required to perform decorrelator operations, are referred to as terminal available resources. The magnitude of the maximum interference signal that can be processed by the filter unit will be referred to as a matchable filter unit threshold. In view of these points, the present invention includes both a matched filter unit and a decorrelator unit, so that the user data is processed in either the matched filter unit or the decorrelator unit by comparing the result data with the interference signal determination value, and in particular, the result. Adjust the value of α to be close to one (1) or determine the interference signal containing α so that it affects the comparison between the data and the interference signal determination value, for example, so that the interference signal determination value containing the α value remains the same. Adjust the value of α close to zero so that the value is less than it. In this case, that is, in determining the interference signal determination value through the result data processed by either the matched filter unit or the decorrelator, the background noise included in the result data is larger than the decorrelator processable threshold or required to process the user data. If the amount of calculation becomes large and the terminal available resources are insufficient, the value of α is decreased to be close to zero. Thus, the resultant data can be made larger than the interference signal determination value so that the matched filter portion is used. In addition, in determining the interference signal determination value through the result data processed by either the matched filter unit or the decorrelator unit, if the interference signal corresponding to the result data is larger than the matchable filter unit processable threshold value, the α value is set to 1 (1). Increase to). Thus, the interfering signal determination value can be made larger than the result data so that the decorrelator is used. Additionally, those skilled in the art can readily understand that the α value can be adjusted as a specific value within a range of more than zero and less than one (1) depending on the performance of the matching filter portion, the performance of the decorrelating portion, and the amount of terminal resources applied to the present invention. Could be.

In addition, the data symbol determiner 350 has an output value of the matched filter unit 320 or the decorrelator 330 and determines a value of −1 or 1 according to a predetermined threshold value 0.

4 is an operation flowchart showing a multi-user detection method according to an embodiment of the present invention.

First, the user data is input to the matched filter unit 320 or the decorrelator 330 to calculate the result data (S401).

Thereafter, the interference signal determination value including the α value is determined based on the calculated result data (S402). In this case, the interference signal determination value is determined based on the correlation coefficient and the user data amplitude of the result data. In particular, the background noise included in the result data is larger than the decorrelated threshold or the computation amount is large in processing the user data. If the terminal available resources are insufficient, the value of α is decreased to be close to zero, and if the interference signal corresponding to the result data is larger than the matching filter unit processable threshold, the value of α is increased to be close to one.

)과

를 비교하여 어느 쪽이 큰지 여부를 판정한다(S403).Then, the interference signal determination value according to the following equation (

)and

It is determined whether the one is larger by comparing with (S403).

[Equation 5]

)보다

가 큰 경우에는 상기 정합 필터부(320)로 도통시키도록 하여 하기 식에 따른 정합 필터 모드를 수행한다(S404).At this time, the interference signal determination value (

)see

If is large, conduct the matched filter mode according to the following equation by conducting to the matched filter unit 320 (S404).

[Equation 1]

)보다

가 크지 않은 경우에는 상기 역상관부(330)로 도통시키도록 하여 하기 식에 따른 역상관 모드를 수행한다(S405).On the other hand, the interference signal determination value (

)see

If it is not large, it is made to conduct to the decorrelating unit 330 to perform the decorrelating mode according to the following equation (S405).

[Equation 4]

Here, although FIG. 4 illustrates an example of performing a matched filter mode (S404) or performing a decorrelating mode (S405), and then proceeding to a comparing step (S403), after performing a matched filter mode (S404) or performing a decorrelating mode (S405). It is also possible to proceed to the α value determination step (S402) and the scope of the present invention is not limited thereto.

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

 According to the present invention, by using a switching method, a matching filter method is used when the background noise is large and an decorrelator method is used when the user interference signal is large, thereby reducing the bit error rate of the receiver and reducing the amount of computation. There is this.

Claims (7)

In the multi-user detection device, A switching unit transferring at least one user data input from the outside by a switching control of the control unit to any one of a matching filter unit and a decorrelating unit; The matching filter unit matching at least one user data input from the switching unit using a correlation to output the result data as result data; The decorrelating unit for matching at least one user data input from the switching unit using a correlation and applying an inverse correlation coefficient to output the result data as result data; And The interference signal determination value is determined through the correlation coefficient and the user data amplitude of the result data processed by either the matching filter unit or the decorrelating unit, and if the determined interference signal determination value is smaller than the result data, external user data. The control unit to control the switching unit so that the control unit is transmitted to the matching filter unit, and if the determined interference signal determination value is larger than the result data, the control unit controls the switching unit so that external user data is transferred to the decorrelator unit. Multi-user detection device comprising a. The method of claim 1, And said interference signal determination value is the following [Equation]. [Equation]

Where 0 <α <1, h is user data amplitude, γ is correlation coefficient The method of claim 2, The control unit, The background noise included in the result data processed by either the matched filter unit or the decorrelator is greater than a threshold value that can be processed by the decorrelator, or the user filter is processed by either the matched filter unit or the decorrelator. If the amount of computation is large and the terminal available resources are insufficient, the value of α is reduced to be close to zero to control external user data to be processed in the matching filter unit. If the interference signal corresponding to the data processed by either the matching filter unit or the decorrelating unit is greater than the matching filter unit processable threshold, the α value is increased to be close to one (1) so that external user data is inversely reversed. Multi-user detection device characterized in that the control to be processed in the tube. delete In the multi-user detection method, A result data calculating step of processing the at least one user data input from the outside using any one of a matched filter unit use mode or a decorrelator use mode to calculate result data; An interference signal determination value determining step of determining an interference signal determination value through a correlation coefficient for the calculated result data and a user data amplitude; A comparison step of comparing the determined interference signal determination value with the calculated result data; And As a result of the comparison, the use mode activation step of activating the matching filter unit using mode when the interference signal determination value is smaller than the result data, and activating the decorrelating unit using mode when the interference signal determination value is larger than the result data. Multi-user detection method comprising a. The method of claim 5, And said interference signal determination value is the following [mathematical formula]. [Equation]

Where 0 <α <1, h is user data amplitude, γ is correlation coefficient The method of claim 6, The determining of the interference signal determination value may include: In the result data calculating step, the background noise included in the result data processed using any one of the matching filter part using mode and the decorrelating part using mode is greater than the decorrelating processable threshold, or the matching is performed in the result data calculating step. When processing user data using any one of the filter unit use mode or the decorrelator use mode, if the amount of computation is large and the terminal available resources are insufficient, the α value is reduced to near zero, In the result data calculating step, if the interference signal corresponding to the data that is processed using either the matched filter unit use mode or the decorrelator use mode is larger than the matched filter unit processable threshold value, the α value is one (1). Multi-user detection method characterized in that the increase to near.

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