Stokes parameters and DOA estimation for nested polarization sensitive array in unknown nonuniform noise environment

To obtain a large aperture for improving parameter estimation performance, this paper introduces a novel polarization sensitive array composed of augmented and optimally nested subarrays with differently oriented antennas, and then proposes an algorithm for direction of arrival (DOA) and Stokes parameter estimation of completely and partially polarized signals, in unknown nonuniform noise environment and without source number knowledge. The aperture of the proposed array significantly increases since the difference co-array of the optimally nested subarray can obtain the maximum degrees of freedom. There is a systematic procedure to determine the numbers of antennas in the two subarrays in order to obtain similar apertures for the two subarrays. Unfortunately, both the difference co-arrays of the optimally nested subarray and between the two subarrays have holes, which degrades performance of parameter estimation. By using oblique projection operators, the proposed algorithm first fills the holes and suppresses the nonuniform noise to obtain hole-free and noiseless difference co-arrays, and then the difference co-arrays are employed to form a block-sparsity model. Finally, based on the model, block orthogonal matching pursuit algorithm is used for parameter estimation. The Cramér-Rao bound and its existence condition are derived. Simulation results are given to demonstrate the superior performance of the proposed array and method.