| With the development of satellite communication technology,the satellite Internet represented by LEO satellite constellations has received widespread attention.The Satellite Internet will play an important role in social development,national life,national security and other aspects because of its low link delay,wide coverage to the ground,low transmission cost and as a supplement to the terrestrial internet.Therefore,both at home and abroad are competing to develop the satellite internet,such as Starlink in the United States,One Web in the United Kingdom,and so on.In order to support the rolling construction of satellite internet,it is necessary to study the corresponding emulation technology for LEO satellite constellation,to verify the new technology in the development of Satellite Internet and to evaluate the security technology for reducing the additional construction costs.The emulation method based on virtualization and cloud computing technology solves the problem of low fidelity and scalability in traditional network emulation technology,and has become the major technology of LEO satellite constellation emulation.However,the unique characteristics of LEO satellite constellation communication link,such as complex and highly dynamic electromagnetic environment scene,pose a challenge to LEO satellite constellation emulation.To address this challenge,based on virtualization and cloud computing technology,this paper focuses on the communication link emulation technology for LEO satellite constellation,and builds an emulation platform for LEO satellite constellation with high fidelity,high emulation accuracy and high dynamics.Specifically,this paper includes:1)A communication link emulation technology for LEO satellite constellation is presented for complex electromagnetic environment.The communication link of LEO satellite constellation is susceptible to the interference of electromagnetic environment.To improve the fidelity of emulation,considering the more complex electromagnetic interference of satelliteearth communication,the common natural electromagnetic environment interference,intersatellite electromagnetic interference and artificial electromagnetic interference are studied.Based on the interference construction and interference emulation,the interference construction and emulation process of communication link of LEO satellite constellation for complex electromagnetic environment is designed.In order to solve the complex and tedious problems in the construction of electromagnetic environment,the natural electromagnetic environment description model,inter-satellite electromagnetic interference description model and artificial electromagnetic interference description model are designed respectively.Through these three models,emulation scenarios containing different electromagnetic environments can be built quickly and automatically.To solve the problem of uncertain inter-satellite communication links in the interference emulation process,an automatic extraction algorithm of interference links is proposed,which can automatically divide the interfered links and compute the link performance data in the communication links.In order to solve the problem that there are many kinds of artificial electromagnetic interference in the emulation process of interference link,an emulation technology combining link performance data with interference signal is presented.The interference signal data is generated by the mathematical model and loaded into the emulation node.The type of artifical eletronmagnetic interference can be identified by the characteristics of the interference signal.Experiments show that the LEO satellite constellation scene with different electromagnetic environments can be quickly built by the interference construction and emulation process.Compared with the manual construction,the speed is improved by at least 70%.The errors of link emulation and link delay emulation for various electromagnetic interference situations are between 0.01%～4.39%,and the errors of packet loss rate emulation are between 0%～14.03%.At the same time,the common artificial electronmagnetic interference can be identified.The emulation efficiency and fidelity of LEO satellite constellation communication link under electromagnetic interference are improved.2)A dynamic emulation technology of communication link for LEO satellite constellation is presented.The communication link of LEO satellite constellation has the characteristics of dynamic changes in link parameters,topology and human factors.For this feature,a dynamic emulation architecture based on cloud platform is designed.To solve the time-varying problem of link performance parameters,the whole process of link performance parameters emulation is studied,and a distributed emulation technology for satellite links is proposed.By distributing all link performance emulation operations to specific emulation nodes,the synchronization accuracy of dynamic emulation for link performance parameters is improved.To solve the topology time-varying problem caused by satellite movement,the timevarying law of topology is studied,and a real-time topology emulation technology based on time slice is proposed.By dividing and emulating the topology into time slices,the real-time accurate change emulation of the emulation topology is achieved.In order to solve the problem that the unexpected man-in-loop operation causes the dynamic change of satellite topology during the operation of satellite,the whole process of the topology change brought by man-in-loop is studied,and a dynamic emulation control technology of satellite link is proposed.By extracting the modified satellite orbit information and recalculating the related links,any realtime reconfiguration of the emulation topology is realized.Experiments show that the satellite link distributed emulation technology improves the synchronization accuracy of link performance emulation by 96% compared with traditional methods.Real-time topology emulation technology based on time slice can achieve accurate and real-time topology change in the scenario of topology change caused by broken satellite communication link.Satellite link dynamic emulation control technology can accomplish any real-time reconfiguration of the emulated topology in scenarios caused by human-in-loop operation.3)Based on the research results of 1)and 2),a dynamic emulation system for LEO satellite constellation based on STK and Open Stack is designed and implemented from five aspects: physical layer,device layer,data layer,service layer and user layer.The design and implementation of key technologies,such as diverse user interaction interfaces,communication link emulation for complex electromagnetic environment,communication link dynamic emulation,data collection of emulation,are mainly discussed.For typical Starlink constellation,the key technologies and functions of the system are validated,and for typical routing attack security,the system has a certain supporting role for security technology evaluation. |
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