RIBCE: RIS-BS Virtual Array Based Channel Estimation for mm-Wave Communication System

Reconfigurable Intelligent Surface (RIS) is an emerging technology capable of manipulating the propagation environment, expected to play a vital role in all future wireless communication networks. This paper addresses the important and challenging channel estimation (CE) problem of a fully passive RIS-assisted communication system. We combine RIS array elements and Base Station (BS) antenna elements, forming a virtual multi-dimensional array referred to as the RIS-BS virtual array. Leveraging this array, we propose two algorithms: RIBCE-Compressive Sensing (CS) and RIBCE-Estimation of Signal Parameters via Rotational Invariance Techniques (ESPRIT), to jointly estimate the angle of arrival (AoA) and angle of departure (AoD). The corresponding channel gains are then computed using the estimated AoA and AoD. A lower bound on the pilot overhead is also provided with these proposed algorithms which shows a significant reduction in the pilot requirement compared to state-of-art (SoA) approach. Simulation results are also provided which corroborates the theory and shows a significant performance improvement over the state-of-art approach.