Estimation of DOA and Polarization Parameters with 2-Level Nested Vector-Sensor Array Based on Quaternion Model

The quaternion coherence problem exists in the data model of the conventional dimensional reduced quaternion estimation of signal parameters via rotational invariance techniques(DRQ-ESPRIT), and DRQ-ESPRIT would lose degrees of freedom(DOFs)when it is used to implement the spatial smooth operation. An improved DRQ-ESPRIT algorithm based on 2-level nested vector-sensor array is proposed in this paper. The quaternion coherence problem is solved by switching the multiplication sequence of spatial direction vector and electric field. Meanwhile, nested array and Khatri-Rao subspace approach are used to increase the number of DOFs, thus the proposed algorithm can estimate more incident sources than DRQ-ESPRIT, and the estimations of direction of arrival(DOA)and polarization parameters are more accurate. Simulation results demonstrate the effectiveness of the proposed algorithm.