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

Automated summary

This study proposes a cascaded channel estimation framework for RIS-assisted mmWave communications, taking into account the wideband effect and using the Newtonized orthogonal matching pursuit algorithm for channel parameter detection. The Cramer-Rao lower bound is introduced to evaluate the channel estimation performance. Numerical results demonstrate the effectiveness of the proposed channel estimation scheme.