Channel Estimation for RIS Assisted THz Systems With Beam Split

Reconfigurable intelligent surface (RIS) is considered to be a promising technology for future terahertz (THz) communications. However, due to ultra bandwidth and large scale of antenna arrays at base station and RIS, RIS-assisted THz communication would suffer from severe beam split effect, which poses significant challenges in channel estimation. In this letter, we propose a novel cascaded channel estimation scheme, i.e. regularized sensing beam split based orthogonal matching pursuit (RSBS-OMP) for a practical RIS-assisted wideband THz multi-user system. The cascade channel estimation is formulated as a sparse parameter recovery problem and RSBS-OMP algorithm is utilized to estimate channel parameters. Numerical simulations show that performance of the proposed RSBS-OMP method outperforms existing algorithms in terms of normalized mean-square-error.