Extending available spectrum in cognitive radio: Hierarchical spectrum sharing network

Cognitive radio (CR) is an emerging communication paradigm to address spectrum insufficiency by opportunistically accessing inactive spectrum. Normally, there are several distinct wireless systems co-existing in the same area. Hence, how to efficiently share the available spectrum among these systems becomes a significant challenge in CR. In this paper, a spectrum-heterogeneity-based hierarchical spectrum sharing network (HSSN) is proposed for CR. In HSSN, available spectrum bands are classified into two categories. To enable the infrastructure, spectrum identification and classification are developed, and the strategies on how to effectively utilize these two types of spectrum are also discussed. In addition, the associated protocol is exploited for spectrum selection and route forwarding. Analysis and simulation results indicate that the HSSN can significantly improve spectrum utilization and provide a considerable extension to the available spectrum.