On the Performance of Hybrid FSO/RF System Over Generalized Fading Channels

In this paper, we analyze the performance of a single-threshold-based switching scheme for hybrid free space optics/ radio frequency (FSO/RF) system over generalized FSO and RF fading channels. The turbulence induced fading in FSO link is modeled using generalized Malaga distribution and the RF channel fading is modeled using recently proposed generalized $\alpha-\eta-\kappa-\mu$ distribution. In addition, the effect of pointing errors and atmospheric attenuation are also taken into consideration to evaluate the system performance assuming heterodyne detection (HD) and intensity modulation/direct detection (IM/DD) techniques. The unified closed-form expression for average symbol error rate (SER) is derived. Further, the asymptotic expression is also derived in closed-form to obtain the diversity gain of the hybrid system. The effect of various FSO and RF channel parameters on the system performance has been investigated and the coding gain obtained due to RF backup link over single-link FSO system has also been reported. Finally, all the derived expressions are validated using Monte-Carlo simulations.