Based On The Study Of Hybrid Network For Cognitive Radio Network Synchronization

In recent years, cognitive radio and cognitive wireless networks has become a hotresearch field of wireless communications.Scholars and experts have studied suchtechnology as spectrum sensing and resources allocation in depth, but study of wirelessnetwork networking synchronization based on cognition is rarely reported. There arestill many key technologies to be resolved. This thesis closely combines national863high-tech projects--wireless broadband communication system based on dynamicspectrum resources", and focuses on the hybrid network networking synchronizationbased on cognitive radio.Hybrid networks based on cognitive radio has characteristics of variablemulti-channel, dynamic topology, and heterogeneous network interconnection.Thisrequirres networking synchronization protocol has not only time synchronizationmethod, but also channel synchronization solution; and need not only implementnetworking synchronization of a single network, but also implement networkingsynchronization of two different structure type which are centralized network anddistributed network.Tranditional networking synchronization protocols are designedbased on single and constant channel without function of channel synchronization,which is unable to adapt to the network synchronization requirements of cognitive radionetworks.While the CR-Sync protocol especially designed for cognitive wirelessnetworks is based on network synchronization in the common control channelmechanism.It is also not suited to hybrid cognitive network without constant commoncontrol channel.This thesis analysises existing networking synchronization protocol, improves andexpands the CR-Sync protocol taking the tree synchronization protocol in reference, andproposes the Hybrid Network Synchronization Based on Cognitive Radio(CR-HNS).The protocol constructs a synchronization tree with the root node as root of the tree torealize that nodes of the whole network keep the channel synchronization and timesynchronization with root node. This protocol innovatively makes use of the mechanism of dynamic root selectionand the synchronization tree maintenance, and enhances the recoverability andscalability of the network.The inner gateway technology is majorly designed tocomplete heterogeneous interconnection of centralized and distributed networks.Timesynchronization employs duplex time synchronization method and linear fittingtechnique to improve accuracy of time synchronization.In addition, It designs themechanism of channel switching and mobility management, and enhances thepracticality of the protocol and user transparency.At the end of the thesis, the CR-HNS protocol is verified and analysised on a realcognitive radio platform based on dynamic spectrum resource sharing.The test resultshows that the CR-HNS has better performance than CR-Sync in time accuracy andnetwork robustness, and also has practical effect.