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

• US 7,388,900 B2
• Filed: 07/05/2005
• Issued: 06/17/2008
• 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
• Primary Examiner(s): Liu; Shuwang
• Assistant Examiner(s): Timory; Kabir A
• Application Number:
  US11/175,119
• Publication Number:
  US 20050286615A1
• Time in Patent Office: 1,078 Days
• Field of Search: 375/130, 375135-136, 375/140, 375146-147, 375149-150, 375/267, 375/264, 375/278, 375/295, 375/316, 375/341, 375346-349, 375107-109
• 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 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 including values of P taps, where the value of P equals 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. 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.

Claims

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

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 P taps, where the value of P equals the period of a basic code used for channel estimation, and the values of the P taps are values sampled at time spots during the period of the basic code;

b. determining the P taps whose values contain a signal response component and the P taps whose values contain noise response component, and obtaining a noise response matrix of said antenna array from said original channel estimation result; 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 a mean-power of each one of the P taps using said original channel estimation result of the antenna array, judging whether the mean-power of each one of the P taps is equal to or greater than a preset threshold value, respectively, if yes, keeping the value of each one the P taps as that of a processed original estimation result, otherwise setting the value of each of the P taps to zero as that of a processed original estimation result;

b02. subtracting said processed original estimation result from said original channel estimation to obtain the 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 the mean 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 values of P1 taps that have larger energy as those of the processed original estimation result and setting values of each of the other P 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 the 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:

$R_{n<br><br><br><br>s}=\frac{N^{\mathrm{\prime <br><br>}}*N^{\mathrm{\prime <br><br>}<br><br><br><br>H}}{L_1<br><br>D},$

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, which is the number of P taps whose values represent noise components;

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

D is the noise deteriorate factor representing the deterioration of the signal-to-noise ratio introduced by a channel estimation algorithm.

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

$R_{n<br><br><br><br>s}=\frac{N^{\mathrm{\prime <br><br>}}*N^{\mathrm{\prime <br><br>}<br><br><br><br>H}}{L_1<br><br>D},$

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, which is the number of P taps whose values represent noise components;

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

D is the noise deteriorate factor representing the deterioration of the signal-to-noise ratio introduced by a channel estimation algorithm.