IRELAX: Interpolated RELAX Algorithm for Enhanced Direction-of-Arrival Estimation

We propose interpolated RELAX (IRELAX) which is a RELAX algorithm incorporating a spatial frequency interpolation method to provide enhanced direction-of-arrival (DOA) estimation. IRELAX is implemented in the coarray-domain of fully-augmentable sparse arrays. The interpolation method approximates the periodogram peak by a parabola and employs three discrete Fourier transform samples around the peak to refine the DOA estimates. Due to the simplicity and efficiency of the interpolation method, the proposed variant allows low-complexity, fast DOA estimation of multiple sources. We provide supporting simulation results with a minimum redundancy array which demonstrate the improved DOA estimation performance of the proposed algorithm over RELAX.