Distributed RIS-based Dual-hop Mixed FSO-RF Systems with RIS-Aided Jammer

Reconfigurable intelligent surface (RIS) is an emerging technology that can result in a dynamically controllable radio propagation environment by smartly tuning the signal reflections via a large number of low-cost passive reflecting elements. In this paper, we investigate the effect of RIS-aided jammer on distributed RIS-based dual-hop mixed free-space optical (FSO)-radio frequency (RF) communication systems. The channel distribution of the FSO link is assumed to follow a Gamma-Gamma (GG) distributed atmospheric turbulence (AT) model with pointing errors (PEs). The relay-RIS and RIS-destination links are assumed to follow Rayleigh distributions. The received signal at the destination node is corrupted by a RIS-aided jammer. It is assumed that the jammer-RIS and RIS-destination links follow a Rayleigh distribution. Novel closed-form expressions for the outage probability (OP) and bit error rate (BER) of the considered system are derived considering two types of detection schemes, namely intensity modulation/direct detection (IM/DD) and heterodyne detection (HD). Through numerical results, it is shown that the presence of the RIS-aided jammer severely degrades the performance of distributed RIS-based dual-hop mixed FSO-RF systems. Finally, the improvement in performance of dual-hop mixed FSO-RF systems with the use of distributed RIS is also validated through results.