Bilateral Multi-Subarray Padded Coprime Array Configuration for DOA Estimation in MIMO Radar

Simultaneous consideration of uniform degrees of freedom (uDOF) and mutual coupling is a key focus in sparse array design. To reduce mutual coupling and increase degrees of freedom (DOF), a bilateral multi-subarray coprime array (BMSCA) is proposed with its specific hole locations in the difference co-array (DCA). To address the holes in the central DCA, an additional subarray is incorporated, resulting in the bilateral multi-subarray padded coprime array (BMSPCA), which substantially increases both DOF and uDOF. Additionally, the first three weight functions and the optimal structure are determined for BMSPCA. As an application, BMSPCA is applied to multiple-input multiple-output (MIMO) radar with sum-difference co-array, where the holes in DCA and virtual sparse sensors can be divided into similar layers and exhibit symmetry; specific sparse arrays that exhibit similar symmetrical properties are then identified, which can fundamentally enhance the uDOF of MIMO radar. Simulation results demonstrate the superior performance of both the proposed array and the sparse MIMO array in scenarios with strong mutual coupling.