Navigation Using Doppler Shift From LEO Constellations and INS Data

Absolute navigation using the downlink communication signals of massive low Earth orbit (LEO) constellations augmented by data from an inertial navigation system (INS) is considered. Lack of atomic clocks on-board LEO satellites requires the use of Doppler shift as a navigation observable. Furthermore, footprint limits of downlink signals’ beams necessitate the use of a tightly coupled INS/radio-navigation filter in order to compensate for the fact that it is not possible to measure carrier Doppler shift simultaneously from eight or more satellites. The navigation solution error is shown for a simulation, which demonstrates the feasibility of combining measurements from LEO constellations and INS data to enable global navigation satellite systems-like navigation capabilities. Additional simulations study how navigation solution error is affected by IMU quality, signal availability, downlink spot beam steering protocol, and constellation characteristics.