| Recently, spectrum resource is getting increasingly scarce. For the reason of its highefficiency of spectrum utilization, cognitive radio (CR) technology has drawn a greatattention. Research into cognitive radio and related technologies has been conducted bymany scholars and research institutions. Different from traditional wireless technology,cognitive radio allows an unlicensed user to access idle licensed spectrum withoutinterfering the licensed user. This special way of using spectrum brings great challengesto routing scheme designing for cognitive radio networks (CRNs).In this paper, the study is started from CRNs’ architecture. We overview the routingschemes in traditional Ad-Hoc networks and learn the characteristic of CRNs. CRNs’requirements for routing scheme are pointed out, as well as the difficulties during thedesigning of routing scheme. A routing scheme should be designed in aspects of routingmetric, routing information exchanging, path generation method, spectrum allocationpolicy, spectrum synchronization and route maintenance. We classify and analyzeexisting routing scheme for CRNs in these aspects.After having an insight into CRN and its routing schemes, we propose the dual-modearchitecture of CRN. In the dual-mode architecture, CRN consists of data network andcontrol network. On the basis of the dual-mode architecture, aiming at the reduction inspectrum requirement and the improvement in spectrum efficiency, we design the path-combination based routing scheme. Simulation shows that this scheme can satisfy thecommunication needs with fewer links, lessen spectrum collisions and reduce spectrumrequirement. As a result, spectrum efficiency is improved. |
PDF Full Text Request