Performance of Mixed RF/FSO with Variable Gain over Generalized Atmospheric Turbulence Channels

In this paper, we consider a free-space optical (FSO) communication scheme with the help of a variable gain relay where the links from the source to the relay are radio-frequency (RF) links while the links between the relay and the destination are FSO links with M-distribution. To mitigate the effects of multipath fading and atmospheric turbulence, we apply transmit diversity at the source and selection combining (SC) at the destination, while the relay is only equipped with single RF receive antenna for receiving signal and one aperture for relaying the information. With this setup, we first derive expressions for the outage probability, bit-error rate, and the average capacity. We further investigate the effect of pointing errors on the system performance.Scopu