A contract-based model for dynamic spectrum sharing

Cognitive radio can improve the utilization of spectrum resources through allowing the unlicensed users (i.e., secondary users) use the spectrum of licensed users (i.e., primary users). The spectrum allocation of the primary user is one of the key issues of cognitive radio technology, and that is how to share the spectrum resources with the secondary users. Market-driven spectrum trading is an efficient way for dynamic spectrum sharing. In this paper, we consider the problem of spectrum sharing in the scenario consisting of one primary user and multiple secondary users, and propose a dynamic spectrum sharing model based on contracts and then solve the model by particle swarm optimization (PSO) algorithm. In this model, secondary users pay to the primary user according to the obtained actual capacity by a certain percentage. The primary user provides different quality of the channel resources to different secondary users, and the spectrum resources are optimized utilization. Simulation analysis shows that the system efficiency on the model is close to the optimal system efficiency in theory.