A utility-based approach for secondary spectrum sharing

This paper provides a social welfare framework for coexistence of secondary users of spectrum in the presence of static primary users. We consider a formulation that captures spatial differences in available spectrum while considering general system topologies and utility functions: a collection of wireless sessions is considered under an arbitrary conflict graph that indicates the sessions which cannot transmit simultaneously on a common channel. It is assumed that each session has a utility associated with its spectrum utilization. A carrier sense multiple accessbased randomized channel selection technique is considered to maximize the resulting sum of utilities. A measurement-based gradient ascent method is used to improve the channel selection performance and to achieve local maxima of the social welfare. Distributed versions of the method are discussed and shown to outperform previously published work in a variety of simulation scenarios that study effects of primary user presence, varying secondary user density, varying total channel availability.