Effective Secrecy Throughput Analysis for Communication Systems with a DF Satellite Relay

In this paper, we investigate a fundamental issue of power control to provide secrecy transmission for a dual-hop satellite communication system consisting of a terrestrial station as the source, a terrestrial station as the destination, a satellite relay in a decode-and-forward manner and two eavesdroppers, which one of the eavesdroppers is a satellite overhearing the source and the other one is surrounding the destination. We derive the closed-form of effective secrecy throughput to reflect an overall performance of security and reliability for the concerned system. Then, a power control scheme is proposed to maximize the effective secrecy throughput by designing the transmit power at the source and that at the relay. Further, the approximation of optimal transmit power above is analyzed and given by closed-form expressions. Finally, numerical results are provided to illustrate the effective secrecy throughput of the dual-hop satellite communication system.