DOA estimation under the existence of multiple groups of coherent signals with ULA

The problem of estimating the direction-of-arrivals (DOAs) of multiple groups of coherent signals with uniformly linear array (ULA) is addressed. An iterative root-MUSIC method is proposed to refine a given coarse DOA estimation by investigating the information carried by the coherency structure among incident signals. The refinement processes for the DOAs associated with distinct sources are implemented in a parallel fashion. Meanwhile, the proposed method is search-free and maintains the effective array aperture. Compared with several representative DOA estimators, numerical examples have verified the effectiveness of the proposed method.