Stackelberg Game Based Secure Transmission Strategy for Cognitive Satellite Terrestrial Networks

Abstract

Recently, the secure transmission in cognitive satellite terrestrial network (CSTN) has gained much attention, where the interference from the terrestrial network is utilized to enhance the security of the satellite network, provided that these two networks share the spectrum. In the existing literature, the satellite and terrestrial networks are assumed to be naturally willing to cooperate with each other to improve the performance of the entire CSTN system. However, these two networks generally belong to different authorities in practice and will not cooperate if their own benefits are impaired. From this perspective, we propose a Stackelberg game based secure transmission strategy for the CSTN to motivate cooperation, where the satellite network acts as the leader and the terrestrial network acts as the follower. Specifically, we model the utility function of the satellite network as the secrecy rate assisted by the terrestrial network. Moreover, the utility function of the terrestrial network is modeled as its obtained transmission rate discounted by the cost of total transmission energy. On this basis, we adopt the backward induction method to determine the Stackelberg equilibrium, from which both the utilities of the satellite and terrestrial networks are maximized. Finally, simulation results are presented to validate our theoretical results.