An Algorithm for Harsh Doppler Shift Estimation for Satellite Communications

Paper i proceeding, 2024

Future communication generations are expected to employ low Earth orbit satellites as a complement to current terrestrial networks. Due to the relatively high speeds of these satellites, harsh Doppler shifts are expected to occur during transmission to a base station on Earth. For use with, e.g., internet of things, lower sampling frequencies at the receiver side might be applied, making the normalized Doppler shifts more severe. In this work, we consider a mathematical formulation of the observed Doppler shift by a ground station as a function of the orbital parameters of the satellite. Based on this description, we propose a standalone model- and pilot-based procedure to estimate normalized Doppler shifts that become larger as the sampling frequency decreases, comprising a simple coarse estimation followed by a refinement stage, which applies linear estimators with consecutively longer data blocks. Simulations show practically unbiased estimates of the strongest observed Doppler shift during a satellite pass, reaching the Cramér-Rao lower bound for a wide range of signal-to-noise ratios.