IRS-Assisted Mixed FSO-RF Communication System with On-Off Controlling

With the potential of reconfiguring the wireless environment, an intelligent reflecting surface (IRS) has been proved to be a viable solution for the next generation wireless communication systems. In this paper, a mixed free-space optical (FSO)-radio frequency (RF) communication system is considered, where an IRS is utilized over the RF hop to empower the end-to-end system performance. In particular, a unified closed-form expression for the outage probability is derived for optical heterodyne detection (OHD) and intensity-modulation with direct detection (IMDD) techniques with on-off controlling at IRS. We also derive the achievable diversity order of the considered IRS-assisted system by obtaining the asymptotic outage performance. The numerical results show that the proposed IRS-assisted system significantly outperforms the conventional mixed FSO-RF system without IRS. Moreover, the impact of the number of reflecting elements, practical reflection amplitude, and controlling mechanism at the IRS is studied on the system performance. The results reveal that the proposed system requires very few reflecting elements to achieve the desired performance as compared to the existing mixed FSO-RF system with IRS.