Performance Analysis of DF Based Cascaded VLC-FSO-VLC System

This paper investigates the performance of decode-and-forward (DF) based cascaded visible light communication-free space optical communication-visible light communication (VLC-FSO-VLC) co-operative system. In the proposed system, the outdoor connectivity is provided by an FSO link and indoor connectivity is provided through VLC environment. The FSO link undergoes the impact of Double Generalized Gamma (DGG) distributed atmospheric turbulence and Rayleigh distributed pointing errors and VLC environment follows the Lambertian radiation pattern of the light-emitting-diode (LED). For this system, using the derived expressions for probability density function and cumulative distribution function of the system's signal-to-noise-ratio (SNR), closed-form expressions of outage probability and average bit-error rate (BER) are obtained. The numerical results show that the performance metrics of the system directly depends on LED-PD (photo-detector) distance, field-of-view (FOV), different atmospheric turbulence conditions, and type of detection technique.