ZTE Communications ›› 2020, Vol. 18 ›› Issue (4): 55-61.DOI: 10.12142/ZTECOM.202004008

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Feasibility Study of Decision Making for Terminal Switching Time of LEO Satellite Constellation Based on the SGP4 Model

ZHOU Ping(), ZHANG Yasheng, SUN Chenhua, XIAO Yongwei   

  1. The 54th Research Institute of China Electronics Technology Group Corporation, Shijiazhuang 050081, China
  • Received:2020-09-14 Online:2020-12-25 Published:2021-01-13
  • About author:ZHOU Ping (616341445@qq.com) received the master’s degree in signal and information processing from Academy of Electronics and Information Technology, China Electronics Technology Group Corporation (CETC). He is mainly engaged in the research of IP protocol.|ZHANG Yasheng received the master’s degree in communication engineering from Xidian University, China. He now works in CETC as a researcher mainly engaged in satellite networking technology. He is the founder and technology leader of satellite communications and IP integration project in the 54th Research Institute of CETC.|SUN Chenhua is a researcher in CETC, mainly engaged in overall design and technology research and development of satellite communication system. Her research interests include satellite constellation networking and satellite-ground network protocols. She has extensive experience in the overall design and system research and engineering design of satellite communication system.|XIAO Yongwei received the master’s degree in communication engineering from China University of Geosciences. He is a senior engineer mainly engaged in the overall design of satellite communication and the research of LEO communication constellation. He was appointed as the deputy chief engineer of major projects in CETC, responsible for the overall work of the space-based access network.


The high speed of low earth orbit (LEO) satellites makes the terminals at each beam tend to switch rapidly and frequently. The predictable trajectories of LEO satellites allow for predictable terminal switching, therefore a simple and highly accurate orbit prediction model is required to swiftly obtain accurate switching time. This study utilizes the simplified general perturbations (Version 4) (SGP4) model to predict the LEO satellite trajectory of WT-1, an LEO satellite developed independently by the 54th Research Institute of China Electronics Technology Group Corporation (CETC). The obtained prediction results are compared with the actual telemetry data of the WT-1, which gives the accuracy of the SGP4 predicted satellite trajectory within 1 km. The terminal entry/exit beam timing is simulated by using the SGP4 model-predicted orbit and the satellite’s own telemetry data. The simulation result shows that the error between the SGP4 model-predicted terminal entry/exit beam timing and the actual timing is less than 1 s. The influence of terminal motion on prediction is discussed. The results show that the error caused by the movement of the ground terminal on the prediction is less than 0.687 s, and the SGP4 model has a definitely practical value for terminal switching determination in the LEO constellation.

Key words: LEO, switching, SGP4, WT-1