Çoklu-atlama hibrit fso/rf haberleşme sistemleri

The reliability of free-space optical (FSO) links is severely restricted by weather-dependent atmospheric phenomena including absorption, scattering and turbulence. An efficient solution is to build hybrid links where a radio frequency (RF) link is incorporated in parallel to the FSO link. With respect to weather conditions, FSO links are mostly degraded by fog and turbulence-induced fading (scintillation) whereas RF links particularly suffer from rain scatter. Therefore, hybrid FSO/RF systems can offer significant enhancements in the system reliability for all weather conditions by means of the complementary nature of the underlying links. In this thesis, we investigate the outage performance of point-to-point hybrid FSO/RF systems as well as multi-hop hybrid FSO/RF systems with soft-switching. Starting from the point-to-point system, we model the link selection required for soft-switching between the FSO and RF channels in different weather conditions by a finite-state Markov chain (FSMC) process. Then, based on the proposed model, we derive a closed-form outage probability expression in terms of various system and weather-dependent parameters. Thereupon, we extend the scope of our analysis to multi-hop hybrid FSO/RF systems. We present the outage probability and diversity gain analysis for multi-hop hybrid FSO/RF systems. Our results clearly demonstrate the robust performance of the soft-switching hybrid FSO/RF systems deployed either as the point-to-point or multi-hop configuration in dealing with different weather conditions.