Balancing Reliability and Utilization in Dynamic Spectrum Access

Future wireless networks will dynamically access spectrum to maximize its utilization. Conventional design of dynamic spectrum access focuses on maximizing spectrum utilization, but faces the problem of degraded reliability due to unregulated demands and access behaviors. Without providing proper reliability guarantee, dynamic spectrum access is unacceptable to many infrastructure networks and services. In this paper, we propose SPARTA, a new architecture for dynamic spectrum access that balances access reliability and spectrum utilization. SPARTA includes two complementary techniques: proactive admission control performed by a central entity to determine the set of wireless nodes to be supported with only statistical information of their spectrum demands, and online adaptation performed by admitted wireless nodes to adjust their instantaneous spectrum usage to time-varying demand. Using both theoretical analysis and simulation, we show that SPARTA fulfills the reliability requirements while dynamically multiplexing spectrum demands to improve utilization. Compared to conventional solutions, SPARTA improves spectrum utilization by 80%-200%. Finally, SPARTA also allows service providers to explore the tradeoff between utilization and reliability to make the best use of the spectrum. To our best knowledge, our work is the first to identify and address such a tradeoff.