On-demand routing protocols for cognitive radio ad hoc networks

Cognitive radio ad hoc networks (CRAHNs) are a class of cognitive radio networks. In recent years, they have gained popularity, and routing protocols have been proposed. Above all, the protocols based on on-demand routing are considered favorable in the literature. It is mainly because the accomplishments of ad hoc on-demand distance vector (AODV) routing and dynamic source routing (DSR) in mobile ad hoc networks have lead to a number of adaptations of both protocols to suit CRAHNs. In this paper, we review the on-demand routing protocols applicable for CRAHNs, which are based on AODV, DSR, and hybrid protocols. After explaining their basic principles, we qualitatively compare the protocols in terms of inherent characteristics and performance. This paper further addresses the pros and cons of routing protocols and discusses research challenges and open issues.