Research On The Key Technologies Of Software Defined Satellite Network

As soon as the concept of satellite network is put forward,it has attracted international attention due to its significant economic value and potential military application.After years of development,satellite network has made a series of technological breakthroughs,but it still faces the difficulties of network upgrading and integration.Software Defined Network(SDN)technology is an effective way to solve these difficulties.Software defined satellite network can realize the decoupling of the control plane and the data plane,which makes the control plane programmable and have the ability of logical centralized control.In this way,software defined satellite network can not only be effectively and thoroughly updated,but also be easy to integrated with the heterogeneous network.In this dissertation,the architecture design,control plane resource optimization and data plane resource optimization of software defined satellite network are studied.The main work of this dissertation can be summarized as follows.1.The system architecture is designed,and performance evaluation models for new generation satellite network topology are proposed.The overall architecture design includes system architecture design and network topology design.As for the system architecture design,the hierarchical structure,call relationship and operation mode are planned.As for the network topology design,performance evaluation models for the new generation satellite network are proposed.The new generation satellite network means large-scale software defined satellite network.According to the characteristics of new generation satellite network,the evaluation models of constellation coverage,inter satellite link,inter satellite collision,SDN controller,network transmission and deployment cost are established.According to the evaluation models,the network topology design is carried out,and the satisfactory solution of network topology design is obtained.Simulation results show that the solution has better network performance and lower deployment cost.2.A set of optimization design methods for SDN controller deployment are proposed.(1)An optimization design method based on virtual topology is proposed,which is suitable for small satellite network.Using the predictability and periodicity of satellite constellation operation,the operation period of satellite constellation is divided into several time periods,and the topology of satellite constellation in each time period can be regarded as fixed.Based on these fixed satellite constellation topologies,the deployment cost model of SDN controller is established.An effective and feasible optimization method is proposed.Due to the small computation cost and the small number of topologies,the computation cost of establishing SDN controller deployment cost model is also small.The simulation results show that the optimization design method based on virtual topology can not only improve the network performance,but also reduce the number of SDN controllers,thus reducing the deployment cost.(2)The optimization design method based on virtual node is proposed,which is suitable for large-scale satellite network.According to the longitude and latitude,the earth is divided into different fixed logical areas.One or more satellites in each logical area can form a virtual node with fixed position,fixed internal delay and fixed external delay,so as to shield the topological time-varying of satellite network.SDN controller will belong to different virtual nodes with the change of time.The deployment cost model is established based on different location combination of SDN controller.An effective and feasible optimization method is proposed.Due to the large number of nodes in large satellite network,using multiple satellites to form a virtual node can effectively reduce the number of nodes,thus effectively reducing the computational cost of establishing SDN controller deployment cost model.The simulation results show that the optimization design method based on virtual node not only ensures the accuracy of calculation,but also improves the efficiency of solution.(3)The optimal design method for phase deployment is proposed,which can further improve the effect of SDN controller deployment in large-scale satellite network.The deployment of large-scale satellite network is often divided into several stages.This dissertation establishes a model based on the deployment cost in different network deployment stages.An effective and feasible optimization method is proposed.The simulation results show that the optimization design method can realize the stable transition of network performance between different deployment stages.3.A set of optimization design method is proposed,which can realize the effective utilization of data plane network resources.(1)The optimization design method for joint allocation of network resources is proposed,which can improve the utilization efficiency of global network resources.The traditional and new network resources,such as bandwidth,flow table,calculation and energy,are defined.The model of joint allocation of network resources is established.Based on Dijkstra algorithm and Lagrange relaxation method,the optimization algorithm is designed.In this algorithm,Dijkstra algorithm is used to allocate the network resources initially,and then Lagrange relaxation method is used to redistribute the network resources in conflict,which can get an effective solution in polynomial time.The simulation results show the effectiveness of the method.(2)The optimization design method for network cache scheduling is proposed,which can realize the reasonable selection of network cache content and improve the utilization efficiency of network cache resources.Network cache is a scheme which can effectively reduce the repeated data transmission by adding cache nodes in the network.Based on the reasonable selection of network cache content,a network cache scheduling model is established,and an optimization algorithm is proposed.The algorithm first uses fixed strategy to reduce decision variables,and then uses branch and bound strategy to find the optimal solution from the remaining decision variables.The simulation results show that the method can achieve better solution efficiency and effect.In a word,this dissertation studies the key technologies of software defined satellite network,completes the system architecture design,puts forward the network topology performance evaluation model for new generation satellite network,puts forward the optimization design method of SDN controller deployment for different scale satellite network,puts forward the optimization design method for joint allocation of network resources,and puts forward the optimization design method for network cache scheduling.The research results of this dissertation are of great significance to promote the development of software defined satellite network.At the same time,due to the effective combination of engineering factors,the research of this dissertation can provide useful reference for engineering practice.