Direction of arrival estimation for co-prime MIMO radar based on unitary root-MUSIC

The issue of direction of arrival (DOA) estimation for co-prime MIMO radar is studied, and an estimation method based on unitary root-MUSIC is proposed. The co-prime MIMO radar has M-element transmit array and N-element receive array with Nλ/2 and Mλ/2 being the inter-element distances, respectively (λ means the wavelength, and M and N are co-prime integers). The algorithm firstly utilizes unitary transformation to transform the complex eigenvalue decomposition (EVD) into real-valued one, which can reduce the complexity. Thereafter, as the virtual elements generated by co-prime MIMO radar are not continuous, the sorting and zero filling operations are carried out to establish a standard polynomial root finding form. Finally, the DOA can be estimated by finding the roots of the polynomials. Due to the using of co-prime array for MIMO radar, the proposed algorithm can achieve much better DOA estimation performance and determine more targets than conventional methods using compact arrays.