NTN Doppler management: pre-compensation, frequency tracking

Doppler Shift in LEO Satellite Systems

Doppler shift is a critical challenge in LEO satellite communication. A satellite at 600 km altitude moves at approximately 7.6 km per second relative to the ground, creating significant frequency shifts in the transmitted signal. At S-band frequencies around 2 GHz, the maximum Doppler shift reaches approximately 48 kHz, while at Ka-band around 20 GHz, it can exceed 480 kHz. The Doppler shift is not constant — it changes continuously as the satellite approaches, passes overhead, and recedes. The rate of change is highest when the satellite is directly overhead, exactly when the elevation…