A Distributed Cooperative MAC for Cognitive Radio Ad-hoc Networks

Cognitive radio has been suggested as an efficient method for secondary users to promote the efficient utilization of spectrum. Meanwhile, Cooperative relay allows different users or nodes to share resources and to create collaboration through distributed transmission in a wireless networks. The combination of Cognitive radio with cooperative communication could significantly improve the system performance in cognitive radio ad-hoc networks (CRAHNs). In this paper, we discuss how to use cooperative relay to increase the transmission rate in CRAHNs. We first give a new distributed relay selection algorithm, it considers several aspects including channel gain, channel available probability and spectrum heterogeneity of secondary nodes. A cooperative MAC protocol, Cooper-MAC, is then proposed for CRAHNs which enables secondary users to negotiate channels and relays. Simulation results demonstrate the effectiveness of the Cooper-MAC.