Integrated enhancement of BDS-3 precise orbit determination and PPP using multiple CENTISPACE™ LEO satellites

Abstract

Low Earth Orbit (LEO) navigation augmentation is widely recognized as a key development for next-generation Global Navigation Satellite System (GNSS), and its performance must be validated using real observations. This paper investigates the contribution of LEO satellites to the enhancement of both BeiDou-3 Navigation Satellite System (BDS-3) Precise Orbit Determination (POD) and Precise Point Positioning (PPP) using real observations collected from multiple CENTISPACE™ satellites, which are equipped with both onboard GNSS receivers and navigation augmentation signal transmitters. First, the BDS-3/LEO integrated POD is conducted using BDS-3/CENTISPACE™ downlink observations collected from regional ground stations together with onboard BDS-3 observations from the LEO satellites. Based on these observations, BDS-3 precise orbits and clock offsets, LEO precise orbits and onboard receiver clock offsets, as well as LEO transmitter clock offsets are estimated and evaluated. The results show that incorporating 1–5 LEO satellites significantly enhances the performance of BDS-3 POD. Specifically, the Three-Dimension (3D) orbit accuracy of Medium Earth Orbit (MEO) satellites improves from 54.7 cm using regional ground stations alone to 11.4 cm after integrating five LEO satellites, representing a 79% improvement. In integrated POD, the CENTISPACE™ LEO satellite orbits achieve an accuracy better than 5 cm, and the averaged standard deviation of the clock errors is 0.22 ns. The generated satellite orbits and transmitter clock offsets of both BDS-3 and CENTISPACE™ satellites are subsequently used for BDS-3/LEO PPP. The positioning results from 12 stations show that the convergence time of the BDS-3 kinematic PPP float solution is reduced from 22.4 to 10.8 min when two LEO satellites are integrated, corresponding to a reduction of 51.8%. These results confirm the dual role of LEO satellites in improving BDS-3 POD and PPP performance.