Direction-of-arrival estimation and Cramer-Rao bound for multi-carrier MIMO radar

Multi-carrier (MC) multiple-input multiple-output (MIMO) radar was recently applied to build sparse virtual arrays with a large aperture for a high-accuracy direction-of-arrival (DOA) estimation. The resulting grating lobes (DOA ambiguities) were resolved using multiple carriers. One problem of MC-MIMO is the coupling of the unknown parameters range and DOA. In this contribution, we study this range-DOA coupling for MC-MIMO systems. We consider both Cramer-Rao bound (CRB) of these parameters and their estimation. We show that a suitable choice of the coordinate system decouples range and DOA parameters in both CRB and estimation. This enables a sequential range and DOA estimation instead of a more complex joint estimation. Explanations of this phenomenon are given and simulation results confirm the theoretical findings.