Systems and Methods for Adaptive Interference Cancellation Beamforming

• US 20110075601A1
• Filed: 09/28/2010
• Published: 03/31/2011
• Est. Priority Date: 09/28/2009
• Status: Active Grant

• Current Assignee: ATC Technology Corporation (FedEx Corporation)
• Original Assignee: ATC Technology Corporation (FedEx Corporation)
• Inventors: Zheng, Dunmin
• Granted Patent: US 8,576,769 B2
• Time in Patent Office: Days
• US Class Current: 370/316
• CPC Class Codes: H04B 7/0617 for beam forming
• 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 7/2041 Spot beam multiple access

Abstract

Methods of operating a transceiver including an antenna having a plurality of antenna feed elements are disclosed. The methods include receiving a plurality of samples of a receive signal from the plurality of antenna feed elements, estimating locations of a plurality of signal sources from the plurality of receive signal samples, identifying a plurality of interference sources from among the plurality of signal sources, generating a plurality of antenna feed element weights w_M in response to the locations of the interference sources, forming an antenna beam from the antenna to the geographic region using the antenna feed element weights w_M, and communicating information over the antenna beam. Related transceivers, satellite gateways and satellites are also disclosed.

Claims

1. A method of operating a transceiver including an antenna having a plurality of antenna feed elements, the method comprising:

receiving a plurality of samples of a receive signal from the plurality of antenna feed elements;

estimating locations of a plurality of signal sources from the plurality of receive signal samples;

identifying a plurality of interference sources from among the plurality of signal sources;

generating a plurality of antenna feed element weights w_M in response to the locations of the interference sources;

forming an antenna beam from the antenna to the geographic region using the antenna feed element weights w_M; and

communicating information over the antenna beam.

2. The method of claim 1, further comprising:

defining a plurality of antenna gain constraint values g_k associated with a plurality of geographic constraint points within a geographic region; and

determining interference weighting factors for the geographic constraint points and locations of the interference sources;

wherein the antenna feed element weights are generated in response to the interference weighting factors.

3. The method of claim 2, wherein generating the antenna feed element weights w_M comprises generating antenna feed element weights w_M that result in antenna response values f_K at the geographic constraint points based on the corresponding antenna gain constraint values g_K and the interference weighting factors at the interference source locations.

4. The method of claim 1, further comprising estimating power levels of the interference sources, wherein the interference weighting factors are determined in response to the power levels of the interference sources.

5. The method of claim 1, wherein estimating locations of the plurality of signal sources comprises:

estimating an array covariance matrix for the plurality of antenna feed elements in response to the plurality of samples of the receive signal to form an array covariance matrix estimate;

generating a spatial spectrum from the array covariance matrix estimate; and

estimating the directions of arrival from the largest peaks of the spatial spectrum.

6. The method of claim 5, wherein generating the spatial spectrum from the array covariance matrix comprises:

performing an eigen-decomposition of the array covariance matrix estimate;

identifying signal eigenvectors and noise eigenvectors for the covariance matrix estimate; and

generating the spatial spectrum in response to the noise eigenvectors and feed array steering data for the antenna array.

7. The method of claim 5, further comprising:

designating signal sources that fall within a predetermined zero-gain zone as interference sources.

8. The method of claim 1, wherein estimating locations of the plurality of signal sources comprises:

estimating an array covariance matrix for the plurality of antenna feed elements in response to the plurality of samples of the receive signal to form an array covariance matrix estimate according to the following equation;

9. The method of claim 8, wherein estimating locations of the plurality of signal sources further comprises:

generating the spatial spectrum from the array covariance matrix estimate according to the following equation;

10. The method of claim 9, further comprising defining a threshold and defining eigenvalues of the array covariance matrix R greater than λ

_T as corresponding to signal space and eigenvalues of the array covariance matrix R less than λ

_T as defining noise subspace, so that the number of eigenvalues of the array covariance matrix R greater than λ

_T is equal to the number K of signal sources.

11. The method of claim 4, further comprising estimating power levels of the interference sources, wherein the interference weighting factors are determined according to the following equation:

19. The transceiver of claim 1, wherein the beam former is further configured to:

estimate an array covariance matrix for the plurality of antenna feed elements in response to the plurality of samples of the receive signal to form an array covariance matrix estimate according to the following equation;

20. The transceiver of claim 19, wherein the beam former is further configured to:

generate the spatial spectrum from the array covariance matrix estimate according to the following equation;

21. The transceiver of claim 20, wherein the beam former is further configured to:

define a threshold λ

_T; and

define eigenvalues of the array covariance matrix R greater than λ

_T as corresponding to signal space and eigenvalues of the array covariance matrix R less than λ

_T as defining noise subspace, so that the number of eigenvalues of the array covariance matrix R greater than λ

_T is equal to the number K of signal sources.

12. A transceiver, comprising:

an antenna having a plurality of antenna feed elements; and

an electronics system including a beam former configured to;

receive a plurality of samples of a receive signal from the plurality of antenna feed elements;

estimate locations of a plurality of signal sources from the plurality of receive signal samples;

identify a plurality of interference sources from among the plurality of signal sources;

generate a plurality of antenna feed element weights w_M in response to the locations of the interference sources; and

form an antenna beam from the antenna to the geographic region using the antenna feed element weights w_M;

wherein the electronics system is configured to communicate information over the antenna beam.

13. The transceiver of claim 12, wherein the beam former is further configured to:

define a plurality of antenna gain constraint values g_k associated with a plurality of geographic constraint points within a geographic region;

determine interference weighting factors for the geographic constraint points and locations of the interference sources; and

generate the antenna feed element weights in response to the interference weighting factors.

14. The method of claim 13, wherein the beam former is further configured to:

generate the antenna feed element weights w_M that result in antenna response values f_K at the geographic constraint points based on the corresponding antenna gain constraint values g_K and the interference weighting factors at the interference source locations.

15. The transceiver of claim 12, wherein the beam former is further configured to:

estimate power levels of the interference sources; and

determine the interference weighting factors in response to the power levels of the interference sources.

16. The transceiver of claim 12, wherein the beam former is further configured to:

estimate an array covariance matrix for the plurality of antenna feed elements in response to the plurality of samples of the receive signal to form an array covariance matrix estimate;

generate a spatial spectrum from the array covariance matrix estimate; and

estimate the directions of arrival from the largest peaks of the spatial spectrum.

17. The transceiver of claim 16, wherein the beam former is further configured to:

perform an eigen-decomposition of the array covariance matrix estimate;

identify signal eigenvectors and noise eigenvectors for the covariance matrix estimate; and

generate the spatial spectrum in response to the noise eigenvectors and feed array steering data for the antenna array.

18. The transceiver of claim 16, wherein the beam former is further configured to designate signal sources that fall within a predetermined zero-gain zone as interference sources.

22. The transceiver of claim 15, wherein the beam former is further configured to:

estimate power levels of the interference sources, wherein the interference weighting factors are determined according to the following equation;

23. A communications satellite, comprising:

an antenna having a plurality of antenna feed elements; and

an electronics system including a beam former configured to;

receive a plurality of samples of a receive signal from the plurality of antenna feed elements;

estimate locations of a plurality of signal sources from the plurality of receive signal samples;

identify a plurality of interference sources from among the plurality of signal sources;

generate a plurality of antenna feed element weights w_M in response to the locations of the interference sources; and

form an antenna beam from the antenna to the geographic region using the antenna feed element weights w_M;

wherein the electronics system is configured to communicate information over the antenna beam.

24. A satellite gateway, comprising:

an electronics system including a beam former configured to;

receive a plurality of samples of a receive signal from the plurality of antenna feed elements;

estimate locations of a plurality of signal sources from the plurality of receive signal samples;

identify a plurality of interference sources from among the plurality of signal sources;

generate a plurality of antenna feed element weights w_M in response to the locations of the interference sources; and

form an antenna beam from the antenna to the geographic region using the antenna feed element weights w_M;

wherein the electronics system is configured to communicate information over the antenna beam.