RARE-based localization for mixed near-field and far-field rectilinear sources

In this paper, a novel localization method for mixed near-field (NF) and far-field (FF) rectilinear or strictly noncircular sources is proposed using the noncircular information for a symmetric uniform linear array (ULA). For FF case, we adopt the NC-MUSIC method to achieve the DOA parameter, for NF case, by exploiting the center symmetrical characteristic of the ULA, we decouple the array steering vectors into two new vectors: one related only to the DOA parameter, and the other dependent on both DOA and range parameters. Based on the principle of rank reduction (RARE), three MUSIC-like estimators are formed to estimate the direction of arrival (DOA) and the range of mixed NF and FF rectilinear sources successively. Meanwhile, distinguishing the types of sources is also solved. The deterministic Cramer–Rao bound (CRB) of the mixed rectilinear signals is derived by the Slepian–Bangs formulation. Simulation results are provided, showing that the proposed method yields a performance better than existing ones.