Cascaded FSO-VLC communication system

The proposed cascaded free space optics (FSO)-visible light communication (VLC) system consists of multiple VLC access points which caters the end users connected via a decode and forward relay to the FSO backhaul link. The FSO link is assumed to be affected by path-loss, pointing error, and atmospheric turbulence while the end-to-end signal-to-noise ratio (SNR) of VLC downlinks are statistically characterized considering the randomness of users position. In this letter, the novel closed form expressions of the statistics like probability density function and cumulative distribution function of the equivalent SNR are derived. Capitalizing on these, the closed form expressions for various performance metrics such as outage probability and error probability are provided. The simulation results are provided to verify the functional curves of mathematical analysis.