KR20100116873A - Method for estimating multi-cell joint channel in time division-synchronous code division multiple access, and joint channel estimation terminal therefor - Google Patents

Abstract

PURPOSE: A method for estimating a multi-cell joint channel in time division-synchronous code division multiple access and a joint channel estimation terminal thereof are provided to reduce the computational complexity of an inverse matrix. CONSTITUTION: A signal receiving part(110) receives a signal transmitted through a communication network. A downlink signal power estimating part(120) receives signals from plural cells. The downlink signal power estimating part presumes the downlink signal power from each cell. A joint channel estimating part(140) presumes a multi-cell joint channel according to a predetermined standard. A joint detection type determining unit(130) determines to perform a multi-cell joint detection.

Description

Method for Estimating Multi-Cell Joint Channel in Time Division-Synchronous Code Division Multiple Access, and Joint Channel Estimation Terminal therefor}

The present invention relates to a multi-cell combined channel estimation method and a combined channel estimation terminal for TD-SCDMA, and more particularly, to a multi-cell midamble matrix without changing the performance of the conventional multi-cell combined channel estimation in a multi-cell environment. The present invention relates to a multi-cell combined channel estimation method in TD-SCDMA for reducing computational complexity through reordering of a channel impulse response (CIR) and a combined channel estimation terminal for the same.

In a time division synchronous code division multiple access (TD-SCDMA) system, joint detection (JD) is applied as a data detection method.

The method described above can eliminate all interference occurring within the reference cell (the cell to which the user belongs), provided that the code and channel impulse response (CIR) of each active user are fully known or estimated. That's the way it is.

However, there is a problem that interference of adjacent cells is still severe for users located at the edge of the cell.

Accordingly, in order to improve data detection performance of users located at the cell edge, multi-cell joint detection (JD) is applied to receive codes of the active users and channel impulse response (CIR) from adjacent cells to eliminate adjacent cell interference. .

On the other hand, inter-cell interference cancellation (IIC), which operates individually in each cell, is applied, which is another method of joint detection, through which interference from adjacent cells is completely eliminated. Or it may be partially removed.

The necessary information in advance for all data detection algorithms is certain channel impulse responses (CIRs) obtained from all relevant users.

In particular, for multi-cell joint detection (JD) and neighbor cell interference cancellation (IIC), the channel impulse response (CIR) of neighbor cells must be accurate to ensure data detection performance.

First, FIG. 1 shows a downlink model of a multi-cell environment in a TD-SCDMA system. If a user (User of FIG. 1) is located at the cell edge, the user will receive interference signals of similar magnitude as the power of the reference cell signal from the adjacent cell.

For example, as illustrated in FIG. 1, a user receives a signal received from Cell 1 and Cell 2, which are adjacent cells, with a power level of a signal received from Cell 0, which is a reference cell. Will be similar to the power size.

As such, it is beneficial for this user to use multi-cell joint detection (JD) and neighbor cell interference cancellation (IIC) for reliable data detection.

In addition, accurate channel estimation plays an important role in data detection.

In general, a user may know active code information in each cell while detecting beacon channels.

In the TD-SCDMA system, a midamble is transmitted for each time slot as shown in FIG. 2 for channel estimation.

2 is a diagram illustrating a time slot structure.

In FIG. 2, the midamble is located between two data blocks in a time slot. Every cell has a separate default midamble code for each cell.

In the downlink, a common midamble is transmitted to all users located in the same cell. Here, the common midamble is derived from the basic cell division midamble code of length L, and the position is shifted by the length by W.

For example, the transmitted midamble may be represented by Equation 1.

Here, L chips (m ₁ to m _L ) are the basic midamble codes, and W chips (m _{L + 1} to m _{L + W} ) after L chips (m ₁ to m _L ) are the first of the basic midamble codes. Repeat the length of W. The channel impulse response (CIR) of the signal received by the user may be represented by Equation 2.

Where W is the length of the CIR. The first (W-1) chips of the received midambles are mixed with the data part of the midamble sent first. As such, subsequent L chips are selected for channel estimation.

This is because the channel estimation is determined only by the midamble without this data part being affected. If the user receives downlink signals from K cells, the corresponding reception midamble part is represented by Equation 3 below.

Here, m ^k and h ^k mean the midamble from the k-th cell and the CIR of the received signal, respectively. n _m denotes a noise vector that inhibits the midamble part. M ^k represents the midamble matrix of the k-th cell and is represented by Equation 4. This is achieved through the convolutional operation between the common midamble and the CIR.

Here, the matrix described above has a size of L X W.

The two channel compensation method described below is a method applied to compensate for the CIR of multiple cells.

First, sequential single cell channel estimation is a method capable of sequentially compensating the CIR of each cell through a Steiner Estimator.

The Steiner compensator performs a cyclic correlation operation based on the basic midamble code of each cell. The Steiner compensator is capable of applying a fast Fourier transform (FFT).

However, a problem arises that the sequential single cell channel estimation method seriously impairs the accuracy of channel compensation because all adjacent cell interference signals are regarded as noise.

Secondly, multi-cell joint channel estimation (Multi-cell JCE) can be expressed by Equation (5).

는 수학식 6과 같은 구조를 갖는 다중 셀 미드엠블 행렬로 나타낸다.From here,

Is represented by a multi-cell midamble matrix having a structure as shown in Equation 6.

Meanwhile, h _MC in Equation 5 is expressed as Equation 7 by combining CIRs of K cells.

The multi-cell JCE operates as shown in Equation 8 with pseudo-inverse and least squares (LS) of M _MC .

Through the above-described process, the multi-cell combined channel estimation method can calculate the CIR of each cell sequentially without any interference.

The estimated CIRs are only affected by noise, and it is possible to obtain more accurate results than the sequential single cell channel estimation scheme.

의 역행렬 연산 때문에 다중 셀 결합 채널 추정 방안의 실행 복잡도가 눈에 띄게 증가한다.However, the multi-cell combined channel estimation scheme has a size of KW * KW.

Due to the inverse operation of, the complexity of execution of the multi-cell combined channel estimation scheme is significantly increased.

가 요구되기 때문이다.The Choleasky algorithm is used for inverse computation, and the computation amount of

Is required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and the present invention provides a method for multiplexing in TD-SCDMA for reducing the computation amount of inverse matrix operations in order to reduce execution complexity in a multi-cell joint channel estimation scheme. There is a technical problem to provide a cell combined channel estimation method and a combined channel estimation terminal for the same.

A combined channel estimation terminal of the present invention for achieving the above object is a signal receiving unit for receiving a signal transmitted through a communication network; A downlink signal power estimator for estimating downlink signal power from each cell when receiving signals from a plurality of cells; And a combined channel estimator for estimating a multi-cell combined channel according to a preset criterion.

The combined channel estimation terminal,

The apparatus may further include a joint detection type determiner configured to determine whether to perform multi-cell combined detection by comparing downlink signal powers from the plurality of cells with a threshold value.

The preset criterion is

이고,

ego,

Where h _New is a channel impulse response vector, M _New is a midamble matrix, e is a received signal, and n _m is a noise vector,

The combined channel estimator estimates a multi-cell combined channel according to the preset criterion.

The received signal is,

It is preferable that the noise vector is added to the product of the multi-cell midamble matrix and the channel impulse response vector.

The received signal (e) is,

이고,

ego,

M _New is a midamble matrix, h _New is a channel impulse response vector, and n _m is a noise vector.

The structure of the multi-cell midamble matrix (M _New ),

이고,

ego,

It is preferable that K is a cell and W represents the same index tap.

The structure of the channel impulse response vector is

이고,

ego,

K is a cell and W is an index tap,

The channel impulse response vector is preferably composed of a group of the same index tap.

은,remind

silver,

Is preferably.

은,remind

silver,

인 것이 바람직하다.

Is preferably.

The combined channel estimation terminal,

The apparatus may further include a data detector configured to extract a channel impulse response of each of the plurality of cells, perform multi-cell combined detection, and detect its own data.

The combined channel estimator,

Cell determination means for selecting a cell for multi-cell combined channel estimation among a plurality of cells and extracting an identification number of the selected cell and the number of the selected cells;

Midamble version detection means for detecting a midamble version of each of the plurality of cells;

Midamble matrix constructing means for constructing a multi-cell midamble matrix;

Combined channel estimating means for estimating a multi-cell combined channel according to a preset criterion; And

And CIR output means for outputting multi-cell channel impulse response taps.

The cell determination means,

When selecting a cell, it is preferable to select the cells in the order of increasing signal power strength values.

Another embodiment of the present invention is a method for estimating a combined channel in a combined channel estimation terminal.

a) estimating downlink signal power from each of the plurality of cells by the combined channel estimation terminal; And

b) the combined channel estimation terminal performing multi-cell combined channel estimation;

B),

b-1) extracting an identification number of a cell for multi-cell combined channel estimation and the number of cells selected from the plurality of cells;

b-2) detecting a midamble version of each of the plurality of cells;

b-3) constructing a multi-cell midamble matrix;

b-4) estimating a multi-cell combined channel according to a preset criterion; And

b-5) outputting the multi-cell channel impulse response taps.

After step b) above,

Extracting, by the combined channel estimation terminal, channel impulse responses of each of the plurality of cells; And

The joint channel estimation terminal performs multi-cell joint detection and detects its own data.

As described above, the multi-cell combined channel estimation method in the TD-SCDMA of the present invention and the combined channel estimation terminal for the same are performed through a column change of a multi-cell midamble matrix and rearrangement of a channel impulse response (CIR) vector. Since the new block-to-fleet matrix is generated and applied, it is expected that the computation amount of the inverse matrix operation is reduced in the multi-cell joint channel estimation scheme, thereby reducing the execution complexity without degrading performance. Can be.

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

First, FIG. 3 is a diagram illustrating a configuration of a combined channel estimation terminal according to the present invention.

As shown, the combined channel estimation terminal 100 includes a signal receiver 110, a downlink signal power estimation unit 120, a coupling detection type determination unit 130, a combined channel estimation unit 140, and a data detection unit 150. ).

In more detail, the signal receiver 110 receives a signal transmitted through a communication network.

When the downlink signal power estimator 120 receives signals from a plurality of cells, the downlink signal power estimator 120 estimates downlink signal power from each cell.

Here, the plurality of cells means that both the reference cell and the neighboring cell where the user is located and receiving service are included.

The joint detection type determiner 130 determines whether to perform the multi-cell joint detection by comparing the downlink signal power from the plurality of cells with a threshold value.

For example, the joint detection type determiner 130 may apply an interference value as a threshold value.

The combined channel estimator 140 estimates the multi-cell combined channel according to a preset criterion.

The received signal e represented by the midamble matrix M _New and the channel impulse response (CIR) vector h _New used in the multi-cell combined channel estimation method of the present invention is a multi-cell midamble matrix. Equation 9 is obtained by adding the noise vector to the product of the channel impulse response vector.

Here, M _New is a midamble matrix, h _New is a channel impulse response vector, and n _m is a noise vector.

Equations 10 and 11 are applied to the structure of the multi-cell midamble matrix M _New and the structure of the CIR vector h _new to reduce the amount of computation in the multi-cell combined channel estimation process.

Here, K is a cell and W means the same index tap.

Here, K is a cell, W is the same index tap, and the channel impulse response vector is composed of groups of the same index tap.

4 is a diagram for briefly explaining a multi-cell combined channel estimation method according to the present invention, and shows an example of a CIR vector in a multi-cell combined channel estimation operation with K = 3 and W = 4.

As shown, the multi-cell combined channel estimation scheme of the present invention is composed of groups of W (b), unlike the conventional sequential CIR vector structure (a). Each group includes a tap having the same index for each cell.

Multi-cell combined channel estimation in the present invention is represented by Equation 12 by applying a standard Least Square (LS) solution. This is a preset criterion applied when the combined channel estimator 140 estimates the multi-cell combined channel.

Here, h _New is a channel impulse response vector, M _New is a midamble matrix, e is a received signal, n _m is a noise vector, and the combined channel estimator 140 estimates a multi-cell combined channel according to Equation 12. .

At this time, as shown in Equation 11, taps of the CIRs are sequentially calculated.

Thus, there is no interference by CIR taps of another cell. That is, by extracting the same taps belonging to a cell, an estimated CIR of each cell is derived.

은 역행렬 연산을 간단하게 하기 위해 수학식 13과 같이 대칭 블록-토이플릿 구조로 구성한다.In Equation 12

In order to simplify the inverse matrix operation is composed of a symmetric block-to-fleet structure as shown in equation (13).

는 수학식 14와 같은 구조를 갖는 K * K의 부분행렬이다.Equation 13 is composed of W * W blocks,

Is a submatrix of K * K having the structure shown in Equation (14).

As a result, the computational complexity is significantly reduced because the symmetric block-to-fleet matrix requires only a computational amount of O (K ² W ² ).

The data detector 150 extracts the channel impulse response of each of the plurality of cells, performs multi-cell combining detection, and then detects its own data.

FIG. 5 is a diagram illustrating the configuration of the combined channel estimator shown in FIG. 3 in more detail.

As shown, the combined channel estimating unit 140 includes a cell determination unit 141, a midamble version detection unit 143, a midamble matrix construction unit 145, a combined channel estimation unit 147, and a CIR output unit ( 149).

In more detail, the cell determination unit 141 selects a cell for multi-cell combined channel estimation among a plurality of cells, and extracts an identification number of the selected cell and the number of the selected cells.

Here, the cell determination means 141 selects the cells in the order of the largest signal power intensity value when selecting the cells.

The midamble version detecting means 143 detects a midamble version of each of the plurality of cells.

The midamble matrix constructing means 145 constructs a multi-cell midamble matrix.

Here, the midamble matrix constructing means 145 constructs a multi-cell midamble matrix having a block-to-fleet structure.

The combined channel estimating unit 147 estimates the multi-cell combined channel according to a preset criterion.

Here, the combined channel estimating means 147 applies a value to Equation 12 to estimate the multi-cell combined channel.

CIR output means 149 outputs a multi-cell channel impulse response taps.

6 is a flowchart illustrating a channel estimation and data detection method according to the present invention.

First, the combined channel estimation terminal 100 estimates downlink signal power from each of a plurality of cells (S101).

Subsequently, the combined channel estimation terminal 100 performs multi-cell combined channel estimation (S103).

A more detailed description of step S103 will be described later.

Thereafter, the combined channel estimation terminal 100 extracts the channel impulse response of each of the plurality of cells (S105).

The joint channel estimation terminal 100 performs multi-cell joint detection and detects its own data (S107 and S109).

7 is a flowchart illustrating a method for estimating a multi-cell combined channel according to the present invention in detail, and step S103 of FIG. 6 will be described in more detail.

First, the combined channel estimation terminal 100 extracts an identification number of a cell for multi-cell combined channel estimation and the number of cells selected from a plurality of cells (S201).

Subsequently, the combined channel estimation terminal 100 detects a midamble version of each of the plurality of cells (S203).

Thereafter, the combined channel estimation terminal 100 configures a multi-cell midamble matrix (S205).

Here, the multi-cell midamble matrix is configured to have a symmetric block-toeplitz structure as shown in Equation 13.

The combined channel estimation terminal 100 estimates the multi-cell combined channel according to a preset criterion (S207).

Here, the combined channel estimation terminal 100 estimates the multi-cell combined channel by applying a value to Equation 12.

The combined channel estimation terminal 100 outputs a multi-cell channel impulse response taps (S209).

As such, those skilled in the art will appreciate that the present invention can be implemented in other specific forms without changing the technical spirit or essential features thereof. Therefore, the above-described embodiments are to be understood as illustrative in all respects and not as restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

As described above, the multi-cell combined channel estimation method and the combined channel estimation terminal in the TD-SCDMA of the present invention through the column change of the multi-cell midamble matrix and the rearrangement of the channel impulse response (CIR) vector Since the new block-to-fleet matrix is generated and applied, the computation amount of the inverse matrix operation is reduced in the multi-cell joint channel estimation method, which is suitable for the high necessity of reducing the execution complexity without degrading performance. Do.

1 is a diagram illustrating a downlink model in a multi-cell environment;

2 shows a time slot structure,

3 is a view showing the configuration of a combined channel estimation terminal according to the present invention;

4 is a diagram for briefly explaining a multi-cell combined channel estimation method according to the present invention;

5 is a view showing the configuration of a combined channel estimator according to the present invention;

6 is a flowchart illustrating a channel estimation and data detection method according to the present invention;

7 is a flowchart illustrating a method for estimating a multi-cell combined channel according to the present invention in detail.

<Explanation of symbols for the main parts of the drawings>

100: combined channel estimation terminal 110: signal receiving unit

120: downlink signal power estimation unit 130: combined detection type determination unit

140: combined channel estimation unit 141: cell determination means

143: midamble version detection means 145: midamble matrix configuration means

147: combined channel estimation means 149: CIR output means

150: data detector

Claims (15)

A signal receiver for receiving a signal transmitted through a communication network; A downlink signal power estimator for estimating downlink signal power from each cell when receiving signals from a plurality of cells; And A combined channel estimator for estimating a multi-cell combined channel based on a preset reference; Combined channel estimation terminal comprising a. The method of claim 1, The combined channel estimation terminal, A joint detection type determination unit that determines whether to perform multi-cell joint detection by comparing downlink signal powers from a plurality of cells with a threshold value; Combined channel estimation terminal further comprising. The method of claim 2, The preset criterion is

ego, Where h _New is a channel impulse response vector, M _New is a midamble matrix, e is a received signal, and n _m is a noise vector, The combined channel estimating unit estimates a multi-cell combined channel according to the preset criterion. The method of claim 3, The received signal is, The combined channel estimation terminal, characterized in that the sum of the noise vector to the product of the multi-cell midamble matrix and the channel impulse response vector. The method of claim 4, wherein The received signal (e) is,

ego, M _new is a midamble matrix, h _New is a channel impulse response vector, and n _m is a noise vector. The method of claim 5, The structure of the multi-cell midamble matrix (M _New ),

ego, Wherein K is a cell and W represents the same index tap. The method of claim 6, The structure of the channel impulse response vector is

ego, K is a cell and W is an index tap, The channel impulse response vector comprises a group of the same index tap. The method of claim 7, wherein remind

silver,

Combined channel estimation terminal, characterized in that. The method of claim 8, remind

silver,

Combined channel estimation terminal, characterized in that. The method of claim 1, The combined channel estimation terminal, A data detector extracting a channel impulse response of each of the plurality of cells, performing multi-cell combining detection, and detecting its own data; Combined channel estimation terminal further comprising. The method of claim 1, The combined channel estimator, Cell determination means for selecting a cell for multi-cell combined channel estimation among a plurality of cells and extracting an identification number of the selected cell and the number of the selected cells; Midamble version detection means for detecting a midamble version of each of the plurality of cells; Midamble matrix constructing means for constructing a multi-cell midamble matrix; Combined channel estimating means for estimating a multi-cell combined channel according to a preset criterion; And CIR output means for outputting a multi-cell channel impulse response taps; Combined channel estimation terminal comprising a. The method of claim 11, The cell determination means, Combined channel estimation terminal, characterized in that for selecting a cell in order of the signal power strength value is selected in order. A method for estimating a combined channel in a combined channel estimation terminal, the method comprising: a) the combined channel estimation terminal estimates the downlink signal power from each of the plurality of cells; And b) the combined channel estimation terminal performing multi-cell combined channel estimation; Multi-cell combined channel estimation method comprising a. The method of claim 13, B), b-1) extracting an identification number of a cell for multi-cell combined channel estimation and the number of cells selected from the plurality of cells; b-2) detecting a midamble version of each of the plurality of cells; b-3) constructing a multi-cell midamble matrix; b-4) estimating a multi-cell combined channel according to a preset criterion; And b-5) outputting the multi-cell channel impulse response taps; Multi-cell combined channel estimation method comprising a. The method of claim 14, After step b) above, Extracting, by the combined channel estimation terminal, channel impulse responses of each of the plurality of cells; And Performing, by the combined channel estimation terminal, multi-cell joint detection and detecting its own data; The multi-cell combined channel estimation method further comprises.

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