Group Sparsity-Based Local Multipath Doppler Difference Estimation in Over-the-Horizon Radar

In sky-wave over-the-horizon radar systems, the received signal contains local multipath signal components as a result of reflection and refraction from ionosphere and the earth surface. For a maneuvering target, these multipath signals generally yield three distinct, yet closely separated, and highly time-varying Doppler components. Due to the proximity of these Doppler frequencies, it is a challenging task to accurately estimate the difference between these signatures, which reveal the important elevation velocity of the target. In this paper, we propose a group sparsity-based approach that exploits the correlation between these Doppler signatures and utilizes the a priori information about their characteristics. Simulation results verify the effectiveness of the proposed approach.