Fast Doppler Estimation for LEO Satellites

Significant Doppler shift is observed by ground-based terminals when they communicate through LEO(Low Earth Orbit) satellites and it is essential to characterize Doppler shift in order to get reliable satellite communication links.As shown by analysis of the effects of orbit eccentricity on Doppler-time curves measured by a user on the surface of the earth,Doppler rate increases as the orbit eccentricity of the satellite increases.Furthermore,the Doppler shift expression of a ground-based terminal is derived and avenues that diminish time consumption in Doppler characterization computation are discussed.The approach is validated by numerical simulation.Accurate Doppler-time curves are nicely fitted and the accuracy of the algorithm is higher than 99% for satellites with an orbit altitude of 10 000 km.