Abstract: The cognitive radio is able to provide a wide variety of intelligent behaviours. It can monitor the spectrum and select frequencies that minimize interference to existing PU communication activity.When doing so,it will rely on a set of rules that define which frequencies may be considered,what waveforms may be used, what power levels may be used for transmission.This paper deals mainly with manet based routing protocols performance which greatly depends on availability and stability of wireless spectrum and also a crucial parameter that should not be neglected in order to obtain accurate performance measurements of cognitive radio network.The primary goal of any CR network routing protocol is to meet the challenges of the dynamically changing network topology and establish an efficient route between any two nodes with minimum routing load and bandwidth consumption.Here,we evaluate the performance and comparison of AODV, DSR, DSDV and OLSR routing protocols on the basis of various parameters such as packet delivery ratio, throughput and so on. Finally, select the best performing protocol for CRN networks based on different parameters.

Keywords: Routing protocols, Cognitive radio network (CRN), PDR, Throughput.