LEO: Doppler velocity determination and positioning

In this contribution, the model and performance of instantaneous velocity determination and positioning with Low Earth Orbit (LEO) satellites are investigated for the first time. Owing to the lower orbit, the performance of LEO velocity determination is much more sensitive to the initial receiver position error than that of Global Navigation Satellite System (GNSS). If the magnitude of the receiver position error is 10 m, its impact on the ranging rate will be 7.35 cm/s.

It is found that LEO Doppler shift observations contribute to GPS velocity determination. As for LEO Doppler positioning, even if more than 30 visible LEO satellites are available, the position dilution of precision (PDOP) values can reach several hundreds. Assuming that the error of LEO Doppler measurements is 0.01 m/s, the instantaneous Doppler positioning accuracy can achieve about a few meters, which is comparable to that of GNSS pseudorange positioning. Static LEO Doppler positioning results show that an accuracy at centimeter to decimeter level can be achieved after solution convergence. For a static simulated kinematic positioning test, the RMSEs range from a few decimeters to several meters in different regions by giving different constraints. For a dynamic positioning test, the RMSEs are about 2-3 m in high latitude region.