Survey of Routing Protocols in Cognitive Radio Networks

Cognitive radio (CR) technology is introduced to solve the problem of spectrum underutilization in wireless networks by opportunistically exploiting portions of the spectrum temporarily vacated by licensed primary users. In this paper, we present a survey of recent routing protocols in Cognitive Radio Networks (CRNs). We start by listing routing challenges that should be considered for different types of networks starting by the Wireless Local Area Networks (WLANs) and ending with the Cognitive Radio Networks (CRNs). We then present different routing protocols that are designed for CRNs, we focus on the distributed protocols in which the spectrum availability information is locally constructed at each secondary user in a distributed manner, and we classify them according to the routing metric into four main categories: delay based approaches, link stability based approaches, throughput based approaches and location based approaches. Finally, possible future research directions are discussed.