Estimation method for space correlation characteristics of noise in a time slotted CDMA system

• US 20050286615A1
• Filed: 07/05/2005
• Published: 12/29/2005
• Est. Priority Date: 01/07/2003
• Status: Active Grant

• Current Assignee: Datang Mobile Communications Equipment Company Limited (China Information Communication Technology Group Co. Ltd.)
• Original Assignee: Datang Mobile Communications Equipment Company Limited (China Information Communication Technology Group Co. Ltd.)
• Inventors: Wang, Yingmin
• Granted Patent: US 7,388,900 B2
• Time in Patent Office: Days
• US Class Current: 375/150
• CPC Class Codes: H04B 1/7097 Interference-related aspects
• CPC Class Codes: H04B 17/345 Interference values signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] H04B17/336
• CPC Class Codes: H04B 7/0854 using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 25/0204 of multiple channels

Abstract

The invention discloses a method for estimating the space correlation characteristics of noise in a time slotted CDMA system. The method comprises primarily the steps of: making channel estimation for the received signal of each antenna of an antenna array, respectively, to obtain the original channel estimation result that includes values of taps, P in number, where P is the period of the basic code used for channel estimation; separating the signal response component and the noise response component from said original channel estimation result to obtain a noise response matrix of said antenna array; and making correlation operation with said noise response matrix to obtain a space correlation matrix of noise. By using the channel estimation characteristics of the time slotted CDMA system, the invention provides a method for estimating the space correlation characteristics of noise in a time slotted CDMA system. The method is simple, effective, and of good numerical stability, displaying good performance of estimation in the practical range of signal-to-noise ratio of the system.

Claims

1. A method for estimating space correlation characteristics of noise in a time slotted CDMA system, comprising the steps of:

a. Making channel estimation for a received signal of each antenna of an antenna array, respectively, to obtain an original channel estimation result including values of taps, P in number, where P is a period of a basic code used for channel estimation;

b. Separating a signal response component and a noise response component from said original channel estimation result to obtain a noise response matrix of said antenna array; and

c. Making correlation operation with said noise response matrix of the antenna array to obtain a space correlation matrix of noise.

2. A method according to claim 1, wherein said Step b comprises:

b01. Computing the mean-power of each tap using said original channel estimation result of the antenna array, judging whether the mean-power of each tap is equal to or greater than a preset threshold value, respectively, if yes, keeping the tap value as that of a processed original estimation result, otherwise setting the tap value to zero as that of a processed original estimation result;

b02. Subtracting said processed original estimation result from said original channel estimation to obtain a noise response matrix that contains only the noise response component and zero.

3. A method according to claim 2, wherein said threshold value is a threshold value of power and is a product of a preset signal-to-noise ratio threshold and a noise power.

4. A method according to claim 1, wherein said Step b comprises:

b11. Keeping the values of P1 taps that have larger energy as those of the processed original estimation result and setting values of other taps to zero as those of the processed original estimation result, where P1 satisfies 0<

P1<

P;

b12. Subtracting said processed channel estimation result processed at Step b11 from said original channel estimation result to obtain a noise response matrix of said antenna array that contains only the noise response component and zero.

5. A method according to claim 2, wherein said Step c comprises the correlation operation by means of the formula:

$R_{\mathrm{ns}}=\frac{N^{\mathrm{\prime <br><br>}}*N^{\mathrm{\prime <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>H}}{L_1<br><br>D}$

Where R_ns is the space correlation matrix of noise;

N′

is said noise response matrix;

H is the conjugate transpose operation;

L₁=P−

P₁;

P₁ is the number of taps of which the channel estimation values are kept;

D is the noise deteriorate factor of the channel estimation algorithm.

6. A method according to claim 4, wherein said Step c comprises the correlation operation by means of the formula:

$R_{\mathrm{ns}}=\frac{N^{\mathrm{\prime <br><br>}}*N^{\mathrm{\prime <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>H}}{L_1<br><br>D}$

Where R_ns is the space correlation matrix of noise;

N′

is said noise response matrix;

H is the conjugate transpose operation;

L₁=P−

P₁;

P₁ is the number of taps of which the channel estimation values are kept;

D is the noise deteriorate factor of the channel estimation algorithm.