Dual-Hop Deep Space-Terrestrial FSO/RF Communication under Solar Scintillation: Performance Analysis and Challenges

Deep space communication has been a fundamental guarantee for space exploration but encounters solar scintillation during superior solar conjunction. In this paper, a paradigm for deep space-terrestrial free space optical (FSO)/radio frequency (RF) communication is proposed, and the outage probability performance of the dual-hop amplify-and-forward (AF) based FSO/RF communication system is investigated. Specifically, the asymmetric dual-hop channel models are considered, where the Gamma-Gamma distribution characterizes the FSO link between the deep space probe and a relay satellite that undergoes coronal turbulence. while the RF link between the satellite and the terrestrial receiver follows the shadowed-Rician fading model due to the shadowing effect. Moreover, the closed-form expressions of the outage probability for both channel state information (CSI)-assisted and fixed gain relay systems are presented with the consideration of multiple antennas equipped on the destination, which provide practical insights to the link performance. Simulation results present the validation of our theoretical expressions and highlight a strategy for the improvement of the outage probability performance for deep space-terrestrial communication. Finally, some open issues and research directions that should be further investigated for the actual deep space communication system during superior solar conjunction are identified.