Design Of Space Information Network Architecture For Multi-Layer Satellite Constellation

Space Information Network(SIN)has many advantages such as broad coverage,large scale,and high scalability.SIN is the essential infrastructure to achieve space-terrestrial integrated networking in the future,in which everything is connected,and will play an irreplaceable role on the basis of deep integration with the terrestrial network.On the other hand,with large delay,high error rate,high dynamic topology,limited resources,etc.,the SIN cannot adopt directly the existing technologies of terrestrial network,but need adjust and modify its functions according to space environment,spacecraft platform and network application characteristics.In this paper,aiming at the features of SIN,the design of network architecture is carried out,and a set of initial solutions is proposed from the overall design to sub-disciplinary design.First of all,on the basis of analyzing the development history of the scheme of SIN,the research of network architecture design is systematically combed,and the architecture design is divided into two aspects: overall design and sub-discipline design with key problems respectively.According to the characteristics of SIN,an overall network architecture model based on SDN(Software Defined Network)is proposed,and the architecture design is divided into three categories: network topology,network access and routing strategy corresponding to the network hierarchy.The research points and focuses of each discipline are elaborated respectively,which provide the basis for the specific design.Secondly,aiming at the main features of SIN,starting from the aspects of constellation configuration and inter-satellite link,the network topology design is implemented on the basis of deep analysis of constellation coverage and link performance.Considering multi-constraint,nonlinear and multi-objective complex situations,according to Multidisciplinary Design Optimization(MDO)method,the optimization model is established by using genetic algorithm to optimize the network topology,and the result is obtained through the co-simulation platform.Thirdly,according to the design requirements of network access segment,the Multi-Beam Antenna(MBA)is used as an entry point.Considering the satellite-terrestrial channel model,the structure of antenna elements with 19 elements and 7 beams was designed based on the "equal flux" coverage principle and the beamforming simulation was carried out.Based on the multi-access technology,the SOTDMA(Self-Organized Time Division Multiple Access)scheme which is suitable for the access of spatial information network is designed and the access process of the user terminal is described in detail.Fourthly,aiming at the routing difficulty caused by the topological dynamic of SIN,the network mobility management strategy is designed by the coverage division method based on the analysis of topological dynamic shielded method,and thus the problem can be solved by binding the network address to the geo-location information rather than access equipment.Based on the geo-location information,the evaluation criteria of inter-satellite forwarding path are established,with the abstraction of the network address,and the routing strategies of load balancing and QoS(Quality of Service)guaranteed are proposed.Finally,STK and EXata software are used to build a co-simulation platform of SIN architecture.Simulation examples are given to verify the reliability of the platform and provide support for the design of specific network protocols and further hardware-in-loop network simulation.