Feasibility Analysis of Autonomous Orbit Determination of BDS Satellites with Inter-Satellite Links

  Objectives  The BeiDou-3 navigation satellite system (BDS-3) has designed and implemented a high-speed broadband inter-satellite link (ISL) network on the basis of the BDS-2 to carry out integrated navigation and communication and accumulate valuable measured data for the autonomous orbit determination (AOD) of the satellites. With ISL data, navigation satellite systems can achieve AOD that enables satellites to update their ephemeris on-orbit without the support of the operational control segment. However, the key technologies of the AOD system of global positioning system have not been disclosed. In the last few years, some domestic scholars have carried out some useful research and exploration into AOD with simulation data. But the results of applying the ISL to AOD are still relatively few.

  Methods  The AOD processing model was briefly reviewed on the basis of inter-satellite ranging observations, and a distributed AOD model was built with ISL data. Then, the link building efficiency, constellation geometry, and inter-satellite measurement noise of the 18 medium Earth orbit (MEO) satellites in the BDS-3 constellation were analyzed, and the influences of the initial orbit accuracy and filtering processing interval on the AOD process were also analyzed. Finally, the AOD results obtained via the measured inter-satellite ranging data on the 18 MEO satellites were given and compared with the results of the precision orbit for evaluation and analysis.

  Results  AOD processing and performance analysis are conducted. The analysis results are as follows: (1) The BDS-3 ISLs are rather stable, with about 9 inter-satellite two-way ranging links for each satellite, and the effective ISLs and the constellation geometry could support the AOD of the distributed navigation constellation. (2) The initial orbit accuracy and the filtering interval affect the state evaluation accuracy and convergence velocity. (3) When the initial orbit accuracy is 0.1 m and the filtering interval is 60 s, the user ranging error accuracy of AOD for 30 days is 0.48 m.

  Conclusions  The results confirm the validity of the proposed distributed AOD algorithm.