System and method for estimating the multi-path delays in a signal using a spatially blind antenna array

• US 7,379,757 B2
• Filed: 10/16/2003
• Issued: 05/27/2008
• Est. Priority Date: 10/16/2002
• Status: Expired due to Term

• Current Assignee: CommScope Technologies, LLC (CommScope Holding Company, Inc.)
• Original Assignee: Andrew Corporation (CommScope Holding Company, Inc.)
• Inventors: Alles, Martin, Carlson, John P., Kennedy, Jr., Joseph P.
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): Lee, John J.
• Application Number:
  US10/531,039
• Publication Number:
  US 20060154607A1
• Time in Patent Office: 1,685 Days
• Field of Search: 455/19, 455/24, 455/25, 455/67.13, 455/67.11, 455/562.1, 455/66.1, 455/65, 455/63.4, 455/82, 455/83, 455/277.1, 455/101, 455/115.1, 455/278.1, 455/279.1, 455/67.16, 375/347, 375/349
• US Class Current: 455/562.1
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/0268 by deriving positions from different combinations of signals or of estimated positions in a single positioning system
• CPC Class Codes: H04B 1/1081 Reduction of multipath noise by equalising H04B7/005
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04B 7/0848 Joint weighting
• 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: H04B 7/086 using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming
• CPC Class Codes: H04B 7/0891 Space-time diversity rake receivers H04B1/7115; space-time decoding H04L1/0631
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A method is described that enables a system to estimate the individual times of arrival of multi-path signals components in a received signal while blind to the particular angular response characteristics of an antenna array. Additionally, a system is described that estimate the impulse response of the modulation channel. The impulse response is used to generate impulse response estimates for all multi-path signal components without reference to the actual angle of arrival of the signal. The impulse response for the multi-path constituents are directly associated with the time delays on each path, providing delay estimates for each path.

Claims

1. A method for estimating the multi-path delays τ

_i in a signal using a spatially blind antenna array comprising k arbitrary antenna elements, comprising the steps of;

generating an impulse response h_k for each antenna element k in the antenna array;

determining a vectorized space-time impulse response I over the antenna array;

creating a covariance matrix C;

creating a fictitious array manifold A_f, wherein A_f is spatially blind and independent of the array characteristics; and

resolving the covariance matrix C with the fictitious manifold A_f to thereby estimate the multi-path delays τ

_i independent of the array characteristics.

2. The method of claim 1 wherein the impulse response estimate h_k is determined from the equation:

h_k=(ZZ^H)<sup>−

1</sup>Zr_k

where Z is a delay matrix and r_k is the column vector of the received signal at antenna element k of the antenna array, where k=1,2, . . . m.

3. The method of claim 2 wherein the space-time impulse response vector I is formed by stacking the individual impulse response estimates h_k into a column vector.

4. The method of claim 1 wherein the fictitious manifold A_f is the aggregate of all vectors:

5. The method of claim 1 wherein the covariance matrix C is generated according to the following equation:

6. The method of claim 1, wherein the fictitious array manifold A_f is used to form the space-time manifold and the space-time manifold operates to resolve the multi-path delays.

7. The method of claim 1 wherein the step of resolving the covariance matrix C to determine multi-path delays τ

_i uses the method of MUltiple SIgnal Classification (MUSIC) techniques.

8. The method of claim 1 wherein the step of resolving the covariance matrix C to determine multi-path delays τ

_i uses the Method of Alternating Projection (APM).

9. A method of estimating the multi-path delays τ

_i of a sequence of j blocks of a signal received at an antenna array of k isotropic antenna elements, independently of the spatial array characteristics of the antenna array, comprising the steps of;

deriving channel impulse response estimates h_j,k for each block j at each antenna k;

determining a vectorized aggregate space-time impulse response I for each block j;

forming an estimated covariance matrix for the sequence of j blocks;

providing an array manifold A_f void of spatial information; and

,

resolving the covariance matrix with the array manifold A_f to determine the multi-path delays τ

_i.

10. The method of claim 9, wherein the impulse response estimate h_j,k for block j is determined from the equation:

h_j,k=(Z_jZ_j^H)<sup>−

1</sup>Z_jr_j,k

where Z_j is a delay matrix for block j and r_jk is the column vector of the received signal for block j at antenna k of the antenna array, where k=1,2, . . . m.

11. The method of claim 10, wherein the space-time impulse response vector I is formed by stacking the individual impulse response estimates h_jk into a column vector.

12. The method of claim 9, wherein the fictitious manifold A_f is the aggregate of all vectors:

13. The method of claim 9, wherein the covariance matrix C is generated according to the following equation:

14. The method of claim 9, wherein the fictitious array manifold A_f is used to form the space-time manifold and the space-time manifold operates to resolve the multi-path delays.

15. The method of claim 9, wherein the step of resolving the covariance matrix C to determine multi-path delays τ

_i uses multiple signal classification techniques.

16. The method of claim 9, wherein the step of resolving the covariance matrix C to determine multi-path delays τ

_i uses Alternating Projection.

17. A system for estimating the multi-path delays τ

_i in a signal using a spatially blind antenna array comprising;

an antenna array for receiving the signal;

a means for generating an impulse response h_k for each antenna k in the antenna array;

a means determining a vectorized space-time impulse response I over the antenna array;

a means for creating a covariance matrix C

a means for creating a fictitious manifold A_f, wherein A_f is spatially blind and independent of the array characteristics; and

,

a means for resolving the covariance matrix C with the fictitious manifold A_f to estimate the multi-path delays τ

_i independent of the array characteristics.

18. The system of claim 17, wherein the fictitious array manifold A_f in part forms the space-time manifold and a space-time manifold operates to resolve the multi-path delays.