Research On Routing Algorithm Of Space Information Network

Space Information Network(SIN)is composed of Geosynchronous orbit satellites,mediumlow orbit satellites,and ground stations.It is an important public information infrastructure in China.SIN realizes interactive information through dynamic and three-dimensional intersatellite and satellite-to-ground links,and provides real-time information collection,transmission and processing services.It has the advantages of flexible networking and global coverage.It is used in ocean navigation,aerospace,emergency rescue,disaster relief,intelligent transportation and other fields play a major role.In the face of rapidly increasing task demands,research on the maximum flow routing algorithm of SIN to improve network throughput has become a popular direction in SIN research.Compared with traditional terrestrial networks,SIN have the characteristics of dynamic topology changes and predictable cycles.In addition,poor network connectivity causes nodes to rely on storage-carry-forward transmission.Therefore,it is necessary to use a suitable time-varying graph model to model SIN,and time-expanded graph models the evolution of dynamic topology through the network topology that remains unchanged in each time interval in the graph,and models the storage resources of nodes by connecting nodes in adjacent time intervals through storage edges and the data transmission process of dynamic changes in the topology can be modeled from the two dimensions of time and space.In addition,the satellite nodes in the SIN are restricted by weight and size,and the load capacity of the nodes is limited,resulting in a very limited number of transceivers carried by the nodes.Therefore,it is necessary to consider the condition of the limited number of transceivers,and design a SIN maximum flow routing algorithm based on the time-expanded graph.The traditional maximum flow routing algorithm for SIN with limited transceivers takes into account the constraint of the number of transceivers on the maximum flow of the network,but the allocation strategy of the transceivers and link connection scheme in the entire time interval are fixed,resulting in waste of transceiver resources,inflexible path selection,and low network throughput.In order to make full use of precious transceiver resources,this paper proposes a maximum flow routing algorithm of SIN that combines transceivers and time allocation.First,the timeexpanded graph is used to model SIN,and then under the condition of the limited number of transceivers,with the maximum flow as the goal,each time interval is divided into multiple continuous time periods to support dynamic link switching.Time period is a unit,the transceiver resources are allocated independently,the length of the variable time period and the transceiver allocation strategy in the time period are jointly considered,and the communication link capacity constraints,node storage capacity constraints and flow conservation constraints based on the joint transceiver and time allocation are established.This maximum flow problem is modeled as a mixed integer nonlinear programming model,but this model is very difficult to solve.To this end,this paper uses the big-M method to convert it equivalent into a mixed integer linear programming model.The optimization solver Gurobi can be called to solve the problem using branch and bound method,and the actual SIN topology data derived from the Satellite Tool Kit(STK)software can be used for simulation.The simulation results show that the proposed maximum flow algorithm for SIN based on the combination of transceivers and time allocation,compared with the network maximum flow algorithm that only considers the limited constraints of the number of transceivers,significantly improves the throughput and can support efficient use of multidimensional resources of SIN.