A Distributed Collaborative Game-Theoretic Approach in Cognitive Satellite Communication Networks

Due to the increasing spectrum scarcity in satellite communications and terrestrial communications, cognitive satellite communications have received widespread attention. In this paper, we take the inherent feature that the terrestrial cognitive users suffer from inter-beam interference. In particular, for the first time, we consider the coupling characteristics of channel access and power optimization in opportunistic spectrum access based on distributed frameworks. We first formulate a joint channel access and power optimization game, which is proven to be an exact potential game and accordingly has at least one pure Nash Equilibrium (NE) point. The sufficient conditions for interference-free between cognitive users and for maximization of system utility are given, respectively. Also, the lower bound of the system utility is deduced theoretically. For discrete power control strategies, we then propose a joint-strategy iteration algorithm (JID) to converge to the general NE in two-dimensional discrete strategy space. Especially, to solve the challenge of finding the optimal NE solution in two-dimensional strategy space, we propose a novel joint-strategy iteration algorithm based on exploration and exploitation (JIDEE). Simultaneously, these two algorithms are extended to the case where the power control strategies are continuous. Finally, simulations are conducted to confirm the effectiveness of the formulated game and the two proposed algorithms.