Two-Timescale, Low-Overhead Parametric Channel Estimation for RIS-Assisted Near-Field Communication and Its Rate Implications
New techniques are required to estimate the user-to-reconfigurable intelligent surface (RIS) near-field channel due to the distance-dependency of its steering vector. The estimate is needed to determine the RIS configuration and the combining vector of the multi-antenna base station (BS) receiver. We present a novel, l...