The Application of Gamma–Chi-Square and Nakagami-m Models in the Performance Analysis of a Hybrid RF/FSO System

In this paper, a hybrid radiofrequency/free space optics (RF/FSO) system is considered. The Nakagami-m distribution model was used to describe the RF section in the hybrid system, while the FSO section was described by the Gamma–Chi-square model. The Gamma–Chi-square model is based on the existing FSO channel models of Gamma distribution and Rician distribution. An expression for the outage probability is analytically derived for the considered hybrid RF/FSO system. Numerical results are presented graphically for various system parameters: Nakagami fading parameter m, outage threshold, average signal-to-noise ratio (SNR), Rician factor K, FSO link distance and different atmospheric turbulence levels. Based on the obtained results, it is possible to design hybrid RF/FSO systems with optimal parameters for obtaining the best possible signal transmission performance.