Direction of Arrival Estimation of Coherent Sources in Uniform Circular Arrays Using an Iterative Method

In this paper, an iterative algorithm for direction of arrival (DoA) estimation of coherent sources with a uniform circular array (UCA) is proposed. There is an additional error in the DoA estimation of signals after mapping UCA to virtual uniform linear array (VULA), due to approximation of beamspace transformation. This error depends on the direction of emitters. In the proposed algorithm, the dominant term of error is reduced using two beamformers. Then, the DoA of coherent sources is estimated by construction of Toeplitz covariance matrix and using the MUSIC algorithm. The processes of DoA estimation and reduction of the approximation error are done iteratively. Also, an analytical expression is derived for the approximation of bias for DoA estimation of coherent sources. Simulation results show that the proposed algorithm has a better performance in comparison to the conventional methods.