English

Abstract

The demand for radio spectrum is expected to grow rapidly with the rapid growth of wireless communication in the near future. However, radio spectrum is a limited resource and it is already very crowded. The limited available spectrum and the inefficiency in the spectrum usage necessitate a new communication paradigm to exploit the existing wireless spectrum opportunistically. As it is difficult to accommodate more wireless applications within this limited resource, effective utilization of the unused wireless spectrum is a challenge from spectrum management perspective. To deal with the problems of spectrum congestion and spectrum under-utilization, cognitive radio (CR) has been recently proposed as the solution to current low usage of licensed spectrum problem. The main function for the cognitive radio is detecting unused spectrum, sharing the spectrum without harmful interference with other users and capturing the best scheduling the spectrum. Cognitive radio networks (CRNs) can make full use of spectrum resources of heterogeneous wireless architectures via dynamic spectrum access techniques. However, routing in CRNs impose challenges due to the fluctuating nature of the available spectrum. To study routing algorithm a model that can simulate CRNs routing protocol needs defining. This paper presents a comprehensive summary of different routing models for cognitive radio ad-hoc networks.