Reserch On Spectrum Management And Clock Synchronization Based On Cognitive Radio

"With the rapid development of wireless communication technology,the static exclusive spectrum allocation method makes limited spectrum resources increasingly scarce.Cognitive radio technology enables wireless devices to perceive spectrum information and opportunistically access vacant frequency bands,which effectively alleviates the problem of scarcity of spectrum resources.Therefore,the design and implementation of cognitive radio technology and related systems has become a research direction that has attracted much attention in recent years.This thesis is dedicated to realize a cognitive radio system based on the ZYNQ platform.The spectrum management efficiency of the cognitive wireless system and the network clock synchronization performance are closely related.On the one hand,efficient and reliable spectrum management requires the good clock synchronization characteristics of the cognitive system as a support.On the other hand,to achieve clock synchronization in cognitive wireless networks,it is necessary to consider the scenario where secondary users access spectrum hole dynamically.The above two points supplement each other.Therefore,in order to implement a stable cognitive wireless system,two key issues need to be considered comprehensively.First,it is necessary to design a reasonable spectrum management scheme according to the cognitive communication scenario,and secondly,it is necessary to solve the clock synchronization problem of asynchronous cognitive users in the cognitive wireless network.The following is the main work of this thesis.First,this thesis introduces the background knowledge of cognitive radio technology and sorts out the design points of spectrum management schemes.Then a set of spectrum management schemes based on spectrum pools is proposed.The cognitive system uses the historical information of the licensed spectrum to selectively observe and access channel resources with strong availability,which reduces the cost of spectrum management and improves the utilization of spectrum holes.Second,in order to solve the problem of inefficiency in asynchronous cognitive systems,this thesis first analyzes the existing wireless network synchronization protocols,and on this basis,proposes a cognitive wireless network synchronization scheme suitable for clustered structures.Each node in the cognitive network is synchronized in an orderly manner under the scheduling of the cluster head,which improves the efficiency of network synchronization and achieves a better synchronization state.Finally,on the premise of being familiar with the development process of ZYNQ hardware boards,the proposed spectrum management and clock synchronization schemes are completed in the access layer design.A cognitive wireless communication system is realized combining the proposed scheme,which is verified by actual tests.The system performance is demonstrated and the final results are shown.