Cascaded Channel Estimation for RIS Assisted mmWave MIMO Transmissions

Channel estimation is challenging for the reconfigurable intelligence surface (RIS) assisted millimeter wave (mmWave) communications. Since number of coefficients cascaded channels in such systems closely dependent on product base station antennas and RIS elements, pilot overhead would be prohibitively high. We propose a channel framework an mmWave multiple-input multiple-output system, where wideband effect transmission model considered. Then, we transform into parameter recovery problem use few symbols to detect parameters by Newtonized orthogonal matching pursuit algorithm. Moreover, Cramer-Rao lower bound introduced. Numerical results show effectiveness proposed scheme.