Research On CSMA Scheme With Guard Channels In The Heterogeneous Network

With the rapid development of wireless communication technology and service,heterogeneous networks and cognitive radio technologies are important directions for future development.The future wireless network is a heterogeneous network environment composed of many different kinds of networks.How to allocate spectrum resources reasonably in a heterogeneous wireless network environment to enable more users to effectively share wireless spectrum resources has important research significance and practical significance.The emergence of cognitive radio technology has created a new situation for the integration of the underlying physical interfaces of heterogeneous networks.This dissertation analyzes the characteristics of various spectrum access schemes based on cognitive radio technology in existing heterogeneous networks,and proposes a spectrum access scheme with protection channels in a heterogeneous network environment.Firstly,the scheme is based on the CSMA scheme,adopted a method of setting guard channels to prevent a network from being overloaded in a heterogeneous network environment.Secondly,build the Markov Model of this scheme with queuing theory,and obtain the steady state probability with matrix analytical method,on this basis,two important performance measures were obtained,loss probability and throughput of users.Then discuss the performance of the proposed scheme under the system parameters.At last,design optimization algorithm for getting optimal value of guard channels when system throughput reach the maximum.This algorithm could obtain optimal value of guard channels under different environment to make throughput of system to the top.Result of the simulation shows that the protected network users have higher throughput and lower loss probability when the proposed scheme of this paper compares with the CSMA scheme without guard channel,means the scheme successfully guaranteed the communication quality of the protected network.The proposed scheme and the optimal guard channels value optimization algorithm designed in this paper can improve the effective utilization of spectrum resources in heterogeneous network environment and further improve the performance of the network.