Revisit the performance of Doppler positioning with LEO satellites

Abstract Recently, the Doppler shifts from Low Earth Orbit (LEO) satellites have been used to augment GNSS and provide standalone positioning, navigation and timing services in opportunistic navigation frameworks or GNSS-like navigation systems. In this paper, we proposed a Doppler-only point-solution algorithm for GNSS-like navigation systems operated in LEO. In these systems, LEO satellites are assumed to be modified to support navigation capabilities. Their positions, velocities and clock drifts could be obtained from ephemeris. The proposed point-solution algorithm can estimate the receiver clock drift, position and velocity simultaneously. Then, the main error sources in Doppler positioning are analyzed. As one of the main error sources, satellites’ position error of several meters and velocity error of several centimeters per second would reduce the positioning performance significantly. The LEO doppler positioning accuracy will deteriorate if there are no error corrections for the ionospheric and tropospheric delay rates. Subsequently, the performance of Doppler positioning algorithms is analyzed. The Zero-Difference Doppler positioning accuracy is in meter-level, which is comparable with pseudorange-based positioning in GNSS. By doing difference between satellites, the receiver clock drift is eliminated and the Between-Satellite-Difference Doppler positioning accuracy is improved by about 10% as Doppler Dilution of Precision is reduced by 12.3%. Moreover, we analyzed the sensitivity of initial position error in the LEO-based Doppler positioning and found that the initial position error should be less than 300 km to ensure convergence.