Reconfigurable Intelligent Surface Aided DOA Estimation by a Single Receiving Antenna

Most existing direction of arrival (DOA) estimation methods are based on antenna arrays for line-of-sight (LOS) propagation. In this article, a different and challenging DOA estimation problem with a single receiving antenna in the non-line-of-sight (NLOS) scenario is addressed, where a reconfigurable intelligent surface (RIS) is combined with two robust array spatial covariance matrix (SCM) reconstruction schemes to solve the problem. In detail, a two-stage approach for high-efficiency RIS phase shifting is first designed, and then the Tikhonov regularization criterion and total least-squares (TLS) criterion are respectively exploited for SCM reconstruction with and without phase shift error (PSE), yielding an improved DOA estimation performance with reduced complexity. Theoretical analysis on the performance of SCM reconstruction is conducted, and simulation results are provided to show the effectiveness of the proposed solutions.