On the explanation of spatial smoothing in MUSIC algorithm for coherent sources

This paper presents the necessity analysis and the sufficiency analysis of DOA estimation in coherent situation by means of three different aspects respectively, including the rank of covariance matrix, the correlation coefficient and the phase difference between coherent sources. The analyses explain how spatial smoothing decorrelates the coherent sources and how many times of spatial smoothing are needed to decorrelate completely. Simulation results illustrate the sensitivity of the MUSIC algorithm to the number of spatial smoothing.