Comparative study of routing protocols in Cognitive Radio Networks

Cognitive Radio Networks (CRNs) have been receiving significant research attention due to their ability to address the problems related with the usage of `precious´ spectrum. Majority of the research in the field of CRNs has been carried out at lower two layers of the protocol stack. Very recently people have started working at network and above layers. Due to the dynamic nature of the spectrum available in CRNs, design of routing protocols has been challenging. Our paper mainly focuses on routing in CRN and we also discuss the challenges and classification associated with it. Next, we provide an extensive survey on existing routing schemes in CRNs. Finally, various open challenges in relation with the routing in CRNs are discussed for researchers.