Doppler-Aided Positioning for Fused LEO Navigation Systems

Fused LEO navigation systems have been proposed as a low-cost means of supplementing and backing up global navigation satellite system (GNSS) navigation services based on low-earth orbit (LEO) constellations, which means broadcasting navigation signals based on the spectrum and hardware of the currently planned communication constellation. In this paper, we introduce Doppler-aided positioning to fused LEO navigation systems, which can improve the positioning performance and availability of fused LEO navigation systems by addressing insufficient pseudorange measures caused by insufficient navigation resources or the early stages of system construction. Theoretical analysis and simulation results show that Doppler-aided positioning based on the weighted least squares (WLS) method can improve the positioning accuracy of pseudorange positioning and achieve 95% three-dimensional errors within 21 m, even if the number of pseudorange measurements is less than four. Therefore, Doppler-aided positioning can expand the application scenarios of independent navigation services for fused LEO navigation systems.