Optical Intelligent Reflecting Surface for Cascaded FSO-VLC Communication System

For optical wireless communication, laser-based free-space optical communication (FSO) has high energy utilization efficiency and speed, but is easily blocked and cannot support multiple users. Visible light communication (VLC) based on light-emitting diode (LED) can support multiple mobile users, but has low energy efficiency in long-distance communication. Aiming at the above problems, this article proposes an OIRS-assisted cascaded FSO-VLC system. In this system, we adopt a FSO link with OIRSs at the front end. Multiple OIRSs are utilized to screen the optimal channel, thereby improving the flexibility and robustness of the system. The VLC link is used in the back end to support multi-user mobile communication. By jointly considering atmospheric turbulence, pointing error, OIRS's physical model and VLC geometric model, the closed-form solutions of the system's precise outage probability, asymptotic outage probability and BER have been derived. It is shown through numerical results that the derivation results are accurate. We can observe that both the increase of VLC source's coverage radius in VLC link and the decrease of pointing error in FSO link can effectively improve the system performance. Based on theoretical analysis and simulation results, the effect of each parameter and system design have been discussed.