Performance analysis of the generalized beamforming estimators in the case of coherently distributed sources

The performance of the generalized beamforming (beamscan) and the generalized minimum variance distortionless response (MVDR) estimators are analyzed in this paper. We consider the case of coherently distributed sources, and analyse the errors of the estimates due to the finite number of complex independent identically distributed Gaussian snapshots. Analytical expression for the mean square error is derived and validated by simulation results. This analysis allows also to assess the validity of the small angular spread approximation commonly used in the literature.