RIS-Assisted Hybrid FSO/THZ System with Maximal Ratio Combining

Abstract

This study explores a hybrid framework that merges terahertz (THz) and free space optics (FSO) technologies in a backhaul network. The combined FSO and THz systems leverage reconfigurable intelligent surfaces (RIS) and employ maximal ratio combining (MRC) at the receiver. Specifically, the closedform expressions for cumulative distribution function (CDF) of channel and signal-to-noise ratio (SNR) for RIS-assisted FSO and THz channels are derived by assuming the impediments such as atmospheric turbulence, fading, pointing errors, and pathloss. Using these statistics, outage probability, average symbol error rate (SER), and outage capacity are computed for the proposed RIS-assisted hybrid FSO/THz system. Numerical results compare the proposed hybrid FSO/THz system against various wireless systems, including RIS-assisted FSO, RIS-assisted THz, and hybrid FSO/THz systems without RIS. © 2025 Elsevier B.V., All rights reserved.