Spatial Smoothing PAST Algorithm for DOA Tracking using Difference Coarray

In this letter, we devise a subspace updating algorithm for tracking directions-of-arrival (DOAs) using the difference coarray of a sparse array. Our solution is based on the projection approximation subspace tracking (PAST) framework, where we design new cost function and iterative process via spatial smoothing of the difference coarray output signal. Since the proposed spatial smoothing PAST (SS-PAST) algorithm exploits the aperture of the difference coarray, it attains higher DOA tracking accuracy than the conventional PAST method operating in a uniform linear array. Simulation results demonstrate the effectiveness of the SS-PAST algorithm.