RIS-aided Positioning and Interference Cancellation with a single element Antenna receiver

The problem of estimating the direction of arrival (DOA) of a radio frequency (RF) signal, when the line-of-sight (LOS) channel between the emitter and receiver is obstructed, has long been a challenge in sensing and wireless communication systems. This work proposes a modified Multiple Signal Classification (MUSIC) algorithm that utilizes a single-element receive antenna and harnesses the capabilities of reconfigurable intelligent surfaces (RIS) to obviate this issue. It is demonstrated that by changing the phase-shifts of RIS elements in consecutive snapshots, not only can the DOA estimation problem be solved, but also the cancellation of interfering signals will be addressed. Based on this approach, a promising DOA-based 2-D positioning algorithm is derived by exploiting at least two RISs and a single-element antenna receiver. As shown in the numerical results, the proposed DOA estimation algorithm's RMSE converges to the Cramer-Rao lower bound (CRLB) as the received SNR increases.