Analysis and characterization of dynamic spectrum sharing in Cognitive Radio Networks

Cognitive Radio Networks have emerged in the last years as a solution of two problems: spectrum underutilization and spectrum scarcity. The main idea is to dynamically re-allocate unused licensed frequency bands to secondary users. The focus of this work is on the analysis and characterization of a dynamic spectrum sharing mechanism where primary users have strict priority over secondary ones. We present some tools and criteria that can be used in order to improve the mean spectrum utilization with the commitment of providing to secondary users a satisfactory grade of service and a small interruption probability. Our proposal is based on the application of the fluid limit technique to analyze a stochastic complex system. We support our analysis with representative simulated examples.