volume | PIER Journals

Abstract

The diagonal loading method is a simple and efficient method to improve the robustness of beamformers. However, how to determine the ideal diagonal loading level has not been adequately addressed. In this paper, it is observed in the simulation that the peak of the main beam is moved with the diagonal loading level when there exists a Direction of Arrival (DOA) estimation error. Based on the observation, a novel diagonal loading method is proposed, and a tradeoff exists between the robustness and the interference suppression capability by controlling the peak location of the main beam. As long as the DOA estimation error is less than the half of the width of main beam, the proposed beamformer will not suppress the Signal of Interest (SOI) as interference. Numerical experiments prove the effectiveness of the proposed method.

1. Stoica, P. and R. L. Moses, "Introduction to Spectral Analysis," Prentice-Hall, Englewood Cliffs, NJ, 1997.

2. Capon, J., "High-resolution frequency wavenumber spectrum analysis," Proc. IEEE, Vol. 57, No. 8, 1969.
doi:10.1109/PROC.1969.7278

3. Seligson, C. D., "Comments on high resolution frequency-wavenumber spectrum analysis," Proc. IEEE, Vol. 58, 947-949, 1970.
doi:10.1109/PROC.1970.7825

4. Van Veen, B. D., "Minimum variance beamforming with soft response constraints," IEEE Trans. Signal Process., Vol. 39, No. 9, 1964-1972, Sep. 1991.
doi:10.1109/78.134429

5. Bell, K. L., Y. Ephraim, and H. L. Van Trees, "A bayesian approach to robust adaptive beamforming," IEEE Trans. Signal Process., Vol. 48, No. 2, 386-398, Feb. 2000.
doi:10.1109/78.823966

6. Chen, C. Y. and P. P. Vaidyanathan, "Quadratically constrained beamforming robust against direction-of-arrival mismatch," IEEE Trans. Signal Process., Vol. 55, No. 8, 4139-4150, Aug. 2007.
doi:10.1109/TSP.2007.894402

7. Carlson, B. D., "Covariance matrix estimation errors and diagonal loading in adaptive arrays," IEEE Trans. Aerosp. Electron. Syst., Vol. 24, 397-401, Jul. 1988.

8. Vorobyov, S. A., A. B. Gershman, and Z. Q. Luo, "Robust adaptive beamforming using worst-case performance optimization: A solution to the signal mismatch problem," IEEE Trans. Signal Process., Vol. 51, No. 2, 313-324, Feb. 2003.
doi:10.1109/TSP.2002.806865

9. Lorenz, R. G. and S. P. Boyd, "Robust minimum variance beamforming," IEEE Trans. Signal Process., Vol. 53, No. 5, 1684-1696, May 2005.
doi:10.1109/TSP.2005.845436

10. Li, J., P. Stoica, and Z.Wang, "On robust capon beamforming and diagonal loading," IEEE Trans. Signal Process., Vol. 51, No. 7, 1702-1715, Jul. 2003.

11. Li, J., P. Stoica, and Z. Wang, "Doubly constrained robust beamformer," IEEE Trans. Signal Process., Vol. 52, No. 9, 2407-2423, Sep. 2004.
doi:10.1109/TSP.2004.831998

12. Liu, W. and S. Ding, "A efficient method to determine the diagonal loding factor using the constant modulus feature," IEEE Trans. Signal Process., Vol. 56, No. 12, 6102-6106, Dec. 2008.
doi:10.1109/TSP.2008.2005862

13. Du, L., T. Yardibi, J. Li, and P, Stoica, "Review of user parameter-free robust adaptive beamforming algorithms," Digital Signal Processing, A Review Journal, Vol. 19, No. 4, 567-582, Jul. 2009.
doi:10.1016/j.dsp.2009.02.001

14. Du, L., J. Li, and P. Stoica, "Fully automatic computation of diagonal loading levels for robust adaptive beamforming," IEEE Transactions on Aerospace and Electronic Systems, Vol. 46, No. 1, 449-458, Jan. 2010.
doi:10.1109/TAES.2010.5417174

Dr. Wenyi Wang

Professor Renbiao Wu

Dr. Junli Liang