A Design And Implementation Of Routing Protocol In LEO Satellite Networks

With the development of mobile communications technology,the transmission rate of network is increasing rapidly.While people experience good communication services,the demand for service differentiation and service quality is getting higher and higher.The coverage of terrestrial communication facilities is greatly affected by the environmental conditions.In terrestrial communication network,users in remote or harsh areas can't get good communication experience.Satellite communication system has wide coverage,which is not affected by the ground environment.So,it can cover the blind area of the ground communication system.Now,the satellite communication system is widely used in national defense,security,navigation,commerce,disaster prevention and other fields.In order to realize information globalization,the integration of space and ground is the trend of future networks.Future research on communication networks will pay more attention to satellite communication systems.This thesis mainly studies the technology of inter-satellite routing in LEO satellite networks.Considering the limitations of current LEO satellite routing protocols,this thesis proposes an inter-satellite routing protocol(OPSPF)based on orbit prediction.In this protocol,satellites update their routes by static prediction and dynamic detection.The static routes updating algorithm is periodically executed by the satellite to handle regular link state changes.According to the location information of the node and the distribution of satellites in the constellation,the location distribution of other satellites is calculated.Then the topology of the whole network is predicted.The link state database is used to store the link state information.Dynamic update algorithm is mainly used to deal with unexpected link failure based on Hello packet detection.According to the results of the static prediction algorithm,communicable links is marked.The notification of link failure and the recovery of it is carried out by the flooding of link state update packet.When the link status is updated,the shortest path algorithm is used for routing calculation.Then this thesis describes the runtime communication process of OPSPF routing protocol in detail.In the meanwhile,we build a LEO satellite simulation scenario using QualNet.Then,use the scenario to analyze and compare the performance of OPSPF and OSPFv2,including communication overhead,routing convergence and packet loss rate.The end-to-end performance of OPSPF routing protocol is analyzed using the semi-physical simulation scenario.According to the results,OPSPF routing protocol performs well in the LEO satellite network.It has little communication overhead,short convergence time,low packet loss rate,and little resource consumption for dynamic probing.Finally,this thesis summarizes our research work,analysis the advantages and limitations of OPSPF routing protocol,and look forward to the application prospect of this protocol.