Performance analysis of mixed RF/FSO systems

In this paper, novel expressions for the outage probability of a dual-hop relaying system, which is composed of radio frequency (RF)/free-space optics (FSO) links, are derived. It is assumed that mixed RF/FSO system employs fixed amplify-and-forward (AF) relay, which is corrupted by both noise and single co-channel interference (CCI). The RF link follows Rayleigh distribution, while the FSO link is operating in atmospheric turbulence-induced fading environment modeled by Gamma-Gamma distribution taking pointing errors into account. The interfering channel also experiences the Rayleigh fading. Derived outage probability is reduced to the special case of noise-limited scenario, when the power of single CCI is negligible. In addition, the obtained general expressions are simplified to the case when the effect of pointing errors is neglected and the FSO link is influenced only by Gamma-Gamma atmospheric turbulence. The numerical results are confirmed by Monte Carlo simulations. Based on presented results, it is shown that CCI has very strong impact on the system performance, especially when the second FSO hop is under the influence of favourable transmission conditions.