Research Of Network Resource Utilization And Optimization Strategy Based On Cognitive Radio

With the development of communication technology and the diversification of communication service requirements,more and more wireless access technologies have emerged and been applied.Multiple wireless networks complement and coexist each other,forming a new situation of heterogeneous wireless network convergence.Cognitive radio technology supports multiple air interfaces and protocols.It provides technical support for multimode terminals to vertical handoff between heterogeneous wireless networks.Because different types of wireless networks have great differences in technologies and support capabilities,and diverse terminal services have different network performance requirements.How to choose the appropriate access network for the terminal,and control the admission of users,according to the performances and status of different access networks,so as to maximize the utilization of network resources,while improving the quality of network services and the satisfaction of the overall users is a challenging problem in the convergence of heterogeneous wireless networks.Vertical handover as the key technology of heterogeneous wireless networks convergence is the main research content of this thesis.In view of the problems of the existing vertical handover algorithms in network discovery,network selection and group handover,the following improved algorithms are proposed:(1)For the problem that energy consumption in network discovery during vertical handover and the unreasonable selection of target access network in network selection,a network selection algorithm based on dynamic scan period and fuzzy neural network is proposed.The algorithm is divided into two parts that dynamic adjustment network scan period and the target network selection based on fuzzy neural network.In the network discovery phase,dynamically adjust the network scan period according to the network signal strength and the moving speed of the terminal;In the network selection phase,considering the network signal strength,the available bandwidth,the moving speed of the terminal,and the location information use the fuzzy neural network algorithm to select the optimal target access network for users.The experimental simulation result proves that compared with the comparison algorithms,the proposed algorithm can reduce the number of terminal handover and achieves the goals of balancing the relationship between network discovery efficiency and energy consumption,reducing ping-pong effect,and balancing network load purpose.(2)For the problem that a large number of users make handover requests to the same wireless network in the same time period,but the target network resources is limited,so that resulting in network congestion,group handover algorithm based on dynamic priority is proposed.In order to ensure that the emergency service can receive the service preferentially.First,the initial priority is set for the service according to the type of the user and the type of the service;Then dynamically adjust the service priorities based on the operational urgency and the residual value density of the service;Finally,in order to avoid the bumpy scheduling phenomenon in the process of dynamic adjustment service priorities,the condition for avoiding bumpy scheduling is given.Simulation shows that compared with the comparison algorithms,the proposed algorithm can reduce the blocking rate of the service,improve service completion rate of the overall users while prioritizing services for important service,and allocate the limited network resources more reasonably.