ABSTRACT
This chapter discusses the main issues related to routing in multihop cognitive radio networks (CRNs), including mobility, spectrum awareness, network topology changes, and scalability. It describes a geographical algorithm spectrum-aware routing for cognitive ad hoc network (SEARCH). SEARCH is a completely distributed routing solution that accounts for primary users (PUs), the mobility of cognitive users, and jointly considers the path and channel choices to decrease path latency. It is developed to operate on networks with PUs that have a dynamic nature. The algorithm can be split up into two parts, the initial route set up and the route enhancement/repair. The chapter describes opportunistic cognitive radio multihop (OCR) protocol which has been designed for CRNs with high PU mobility. The relay distance advancements and per-hop transmission delay are used as metrics for this protocol. To improve the performance of the OCR protocol, the selection of the channel and relay node can be made jointly.
