Low angle direction of arrival estimation by time reversal

In a low angle target parameter estimation scenario, the backscattered signals from targets are distorted by clutter and multipath, which degrades the performance of direction-of-arrival (DOA) estimator significantly. This paper presents a novel method using time reversal (TR) technique and coherent signal-subspace method (CSM) for DOA estimation in a low angle scenario. The TR method exploits target information contained in the return echoes due to multipath and adaptively adjusts TR probing waveforms to increase the signal-to-noise ratio (SNR). Furthermore, CSM is adopted to focus the energy of the multipath signal in a predefined subspace so as to exploit the full time-bandwidth product of the target source. We analyze the performance of the proposed new DOA algorithm. Numerical simulations demonstrate its superior performance compared with the conventional DOA estimators.