DOA Estimation for Coherent and Incoherent Targets with Co-prime MIMO Array

In this paper, we consider the problem of DOA estimation for a mix of incoherent and coherent targets by using the monostatic co-prime MIMO array with N sparse transmitting sensors and 2M - 1 sparse receiving sensors. The co-prime MIMO array generates a non-redundant and uniform sub sum co-array with O(MN) contiguous sensors using only O(M + N) physical sensors. Based on the concept of sum co-array equivalence, we can obtain different configurations of virtual MIMO arrays with O(MN) contiguous virtual sensors, and then construct the corresponding virtual data matrices, which provides different tradeoffs between the number of resolvable targets and the maximum number of mutually coherent targets that can be resolved. On the basis of the virtual data matrix and the conventional DOA estimation approaches such as MUSIC, O(MN) mixed coherent and incoherent targets can be resolved only with O(M + N) physical sensors, namely the number of resovable targets exceeds the limitation of the number of physical sensors. Finally, simulation results demonstrate the effectiveness of the proposed DOA estimation method with the monostatic co-prime MIMO array in the presence of both the coherent and incoherent targets.