Method for estimating direction-of-arrival of terminal in multiple co-frequency cells

• US 8,054,785 B2
• Filed: 04/30/2006
• Issued: 11/08/2011
• Est. Priority Date: 05/12/2005
• Status: Active Grant

• Current Assignee: Shanghai Ultimate Power Communications Technology Co., Ltd.
• Original Assignee: Shanghai Ultimate Power Communications Technology Co., Ltd.
• Inventors: Zhong, Nan, Yang, Guiliang, Li, Feng
• Primary Examiner(s): Phillips; Hassan
• Assistant Examiner(s): Choi; Eunsook
• Application Number:
  US11/914,220
• Publication Number:
  US 20080310372A1
• Time in Patent Office: 2,018 Days
• Field of Search: None
• US Class Current: 370/329
• CPC Class Codes: G01S 3/74 Multi-channel systems specially adapted for direction-finding, i.e. having a single antenna system capable of giving simultaneous indications of the directions of different signals systems in which the directions of different signals are determined sequentially and displayed simultaneously G01S3/04, G01S3/14
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers

Abstract

The present invention discloses a method for estimating DOA of a terminal in multiple co-frequency cells, including the steps of: A. obtaining a channel estimation result of at least one terminal expecting a calculation of DOA in an expecting co-frequency cell; B. performing a Direction-of-Arrival estimation for the expecting terminal in the expecting cell based on the channel estimation result through a DOA estimating method with a wave beam scan, a DOA estimating method with a maximum power path, or a DOA estimating method with a primary eigenvector. With the channel estimations of the multiple cells in the invention, accurate channel estimation results of the respective cells may be provided, from which the channel estimation result of the expecting terminal is selected.

Claims

1. A method for estimating DOA of a terminal in multiple co-frequency cells, comprising steps of:

A. obtaining, by a Base Station in any cell of the multiple co-frequency cells, a channel estimation result of at least one terminal expecting a calculation of DOA in an expecting co-frequency cell, wherein the expecting co-frequency cell is a cell of the multiple co-frequency cells and the channel estimation result is obtained through a method for estimating channels of multiple cells;

B. performing, by the Base Station, Direction-of-Arrival estimation for the expecting terminal in the expecting cell based on the channel estimation result;

wherein

in the step B, the Direction-of-Arrival estimation is performed for the expecting terminal in the expecting cell based on the channel estimation result through a DOA estimating method with a wave beam scan, and the performing of the Direction-of-Arrival estimation for the expecting terminal in the expecting cell in the step B comprises;

B11. calculating, by the Base Station, array response vectors of array antennas of a base station to be measured;

B12. calculating, by the Base Station, a space covariance matrix of the expecting terminal from the channel estimation result of the terminal;

B13. scanning, by the Base Station, the space covariance matrix of the expecting terminal with the array response vectors, and determining an angle of an array vector corresponding to a maximum power value as DOA of the expecting terminal;

wherein the space covariance matrix is a Hermitian matrix and a method for solving an eigenvector of the Hermitian matrix comprises a power iteration algorithm, an orthogonal-triangular, QR, decomposition algorithm, or a tri-diagonal algorithm;

or

in the step B, the Direction-of-Arrival estimation is performed for the expecting terminal in the expecting cell based on the channel estimation result through a DOA estimating method with a primary eigenvector, and the performing of the Direction-of-Arrival estimation for the expecting terminal in the expecting cell in the step B comprises;

B31. calculating, by the Base Station, array response vectors of array antennas of a base station to be measured;

B32. calculating, by the Base Station, a space covariance matrix of the expecting terminal form the channel estimation result of the terminal;

B33. solving, by the Base Station, a primary eigenvector of the space covariance matrix, which is an eigenvector corresponding to a maximum eigenvalue;

B34. scanning, by the Base Station, the primary eigenvector of the space covariance matrix of the expecting terminal with the array response vectors, and determining an angle of an array vector corresponding to a maximum power value as DOA of the expecting terminal;

wherein the space covariance matrix is a Hermitian matrix and a method for solving an eigenvector of the Hermitian matrix comprises a power iteration algorithm, an orthogonal-triangular, QR, decomposition algorithm, or a tri-diagonal algorithm.

2. The method for estimating DOA of a terminal in multiple co-frequency cells according to claim 1, wherein the channel estimation result is obtained through a method for estimating channels of multiple cells in the step A with processes of:

A1. estimating, by the Base Station, channels of the multiple cells through the method for estimating channels of multiple cells, and obtaining channel estimation results of the multiple cells;

A2. selecting, by the Base Station, the channel estimation result of the expecting terminal in the expecting cell from the channel estimation results of the multiple cells.

3. The method for estimating DOA of a terminal in multiple co-frequency cells according to claim 1, wherein the array response vectors are formed through discretizing a Uniform Circular Array or a uniform linear array into uniform angles.

4. The method for estimating DOA of a terminal in multiple co-frequency cells according to claim 1, wherein the scanning is a one-time precise scanning or a hierarchically-approaching scanning.

5. The method for estimating DOA of a terminal in multiple co-frequency cells according to claim 1, wherein the solving of the eigenvector of the Hermitian matrix through the power iteration algorithm comprises:

assuming an initial value u₀ being an all-ones column vector, and substituting u₀ into the following formula (51);

v=Ru 

 

(51)

obtaining and substituting v into the following formula (52);

b=v^HRv/∥

v∥

₂² 

 

(52)

obtaining and substituting b into the following formula (53);

u=v/b 

 

(53)

obtaining u, thereby finishing a first iteration;

then substituting u into the formula (51), and obtaining new v;

substituting the new v into the formula (52), and obtaining new b; and

substituting the resultant b into the formula (53), and obtaining new u, thereby finishing a second iteration; and

performing multiple iterations in the same way; and

upon satisfying a predetermined iteration condition, a primary eigenvalue of the matrix R is a real part of b, and a corresponding primary eigenvector is u, wherein ∥

v∥

₂ is a 2 norm of a vector, and v^H is a transposed matrix of v.

6. The method for estimating DOA of a terminal in multiple co-frequency cells according to claim 5, wherein the predetermined iteration condition is that the iteration is terminated upon arrival at a threshold for the number of iterations;

or during the iteration, the iteration is terminated when a difference of b between two consecutive iterations is below a threshold.

7. The method for estimating DOA of a terminal in multiple co-frequency cells according to claim 1, wherein the solving of the eigenvector of the Hermitian matrix through the power iteration algorithm comprises:

assuming an initial value u₀ being an all-ones column vector, and substituting u₀ into the following formula (51);

v=Ru 

 

(51)

obtaining and substituting v into the following formula (52);

b=v^HRv/∥

v∥

₂² 

 

(52)

obtaining and substituting b into the following formula (53);

u=v/b 

 

(53)

obtaining u, thereby finishing a first iteration;

then substituting u into the formula (51), and obtaining new v;

substituting the new v into the formula (52), and obtaining new b; and

substituting the resultant b into the formula (53), and obtaining new u, thereby finishing a second iteration; and

performing multiple iterations in the same way; and

upon satisfying a predetermined iteration condition, a primary eigenvalue of the matrix R is a real part of b, and a corresponding primary eigenvector is u, wherein ∥

v∥

₂ is a 2 norm of a vector, and v^H is a transposed matrix of v.

8. The method for estimating DOA of a terminal in multiple co-frequency cells according to claim 7, wherein the predetermined iteration condition is that the iteration is terminated upon arrival at a threshold for the number of iterations;

or during the iteration, the iteration is terminated when a difference of b between two consecutive iterations is below a threshold.