2D-DOA Estimation in Uniform Circular Arrays in the Presence of Mutual Coupling

This paper introduces an innovative iterative auto-calibration scheme for jointly estimating the two-dimensional (2-D) direction-of-arrival (DOA) and the mutual coupling coefficients for a signal measured using uniform circular arrays. The proposed method, first, leverages an integrated wideband dictionary to mitigate the detrimental effects of the discretization of the continuous parameter space over the considered azimuth and elevation angles. This approach enhances DOA estimation accuracy while significantly reducing computational complexity. With the improved reliability of DOA estimates, in the second step, the method also enables a more accurate estimation of mutual coupling coefficients. By iteratively alternating between these steps, the proposed scheme achieves high accuracy and robustness. In fact, the DOA estimation step utilizes an integrated dictionary in order to iteratively refine the active parameter space, thereby reducing the required computational complexity while maintaining overall performance. The complexity is further reduced by employing only the dominant subspace of the measured signal. Furthermore, the proposed method relies neither on prior knowledge of the number of nonzero coupling coefficients nor encounters ambiguity issues. Simulation results demonstrate the effectiveness of the proposed method.