Robust DOD and DOA Estimation for Bistatic MIMO Radar in Unknown Mutual Coupling and Non-Uniform Noise

In this paper, a robust direction-of-departure (DOD) and direction-of-arrival (DOA) estimation approach for bistatic multiple-input multiple-output (MIMO) radar in unknown mutual coupling and non-uniform noise is proposed. First, by exploiting the property of low rank of the observed covariance matrix and the sparsity of the noise covariance matrix, a truncated nuclear norm minimization problem is cast and solved to eliminate the non-uniform noise and obtain the noise-free covariance matrix. Then, to effectively alleviate the mutual coupling between the elements of transmitting or receiving arrays, two selection matrices with respect to DOA and DOD estimation are respectively constructed and a new covariance matrix is formed utilizing the structural characteristics of the transmitting and receiving mutual coupling matrices. Finally, the rotation invariance in the signal subspace of the new covariance matrix is exploited to estimate the DOD and DOA. Unlike the existing methods with mutual coupling in bistatic MIMO radar, the proposed approach avoids simultaneously discarding both the transmitting and receiving array elements in the procedure of excluding the mutual coupling effect, so it achieves more degrees of freedom and higher estimation accuracy. Simulation results verify the robustness of the proposed approach.