Outage Performance for Mixed FSO-RF Transmission in Satellite-Aerial- Terrestrial Networks

This paper analyzes the outage performance of a satellite-aerial-terrestrial network (SATN), where the satellite-aerial and aerial-terrestrial links utilize free space optical (FSO) with Gamma-Gamma fading and radio frequency (RF) transmission with Rayleigh fading, respectively. In particular, by considering the impacts of pointing error in FSO links, and exploiting transmit beamforming (BF) with imperfect channel state information (CSI) in RF links, we derive an analytical expression for the outage probability (OP) of the considered SATN with a variable-gain amplify-and-forward (AF) protocol. Then, the asymptotical OP expression in high signal-to-noise ratio regime is presented to evaluate the achievable diversity order of the system. Finally, numerical results are given to confirm the validity of the theoretical formulas and reveal the effects of various parameters on the system performance.