Transmit design and DOA estimation for wideband MIMO system with colocated nested arrays

We consider transmit design and direction-of-arrival (DOA) estimation for a wideband multiple-input multiple-output (MIMO) system equipped with a colocated nested array for both transmit and receive. We present a new transmit scheme which separates the transmitted waveforms in the frequency domain, and allows us to form a sum coarray in the wideband case. Based on the proposed scheme, two coherent DOA estimation methods which construct focusing matrices from the difference coarray of the MIMO virtual array are presented to take full advantage of the degrees of freedom (DOF) and improve the accuracy of DOA estimation. Simulation results illustrate that the proposed system exhibits better performance than several competing configurations.