Design of Satellite-Based FSO/QKD Systems Using GEO/LEOs for Multiple Wireless Users

This article proposes the design of a global-scale free-space optics/quantum key distribution (FSO/QKD) network based on a geosynchronous (GEO) satellite as the secret key source and low-Earth orbit (LEO) satellites as relay nodes for multiple legitimate users on the ground. The continuous variable QKD (CV-QKD) protocol with dual-threshold/direct detection (DT/DD) receivers is employed. The system performance is analyzed by considering the spreading loss, atmospheric attenuation, and turbulence. Based on the design criteria for the proposed system, we investigate the feasibility of a case study for the Japan QKD network considering the unauthorized receiver attack (URA) and beam-splitting attack (BSA). In addition, we analyze the secret-key rate performance of the proposed system and perform Monte Carlo simulations to verify analytical results.