Low Overhead Dynamic Spectrum Reallocation in Opportunistic Spectrum Access Networks

Opportunistic spectrum access, which allows secondary users opportunistically access unused licensed channels to exploit instantaneous spectrum availability, is a promising approach to achieve efficient spectrum utilization and mitigate spectrum scarcity. To address the challenge of dynamic spectrum access, one of the most important issues is cooperative spectrum reallocation among secondary users to minimize spectrum handoffs. In this paper, we present a low-complexity approach based on conflict graph to optimize spectrum reallocation by local coordination. In order to reduce communication overhead, we propose two heuristic spectrum selection methods named local observation and metric maximum. Experimental results show two benefits of the proposed schemes. On one hand, the coordination approach can dynamically improve the total system throughput (approximately doubled at most). On the other hand, our heuristic strategies decrease the number of spectrum handoff by up to 20% compared with existing strategies.