GSM is designed to be usable when travelling in a car, but going much faster than that will likely cause problems. It's probably problematic that you're not sta

GSM is designed to be usable when travelling in a car, but going much faster than that will likely cause problems. It's probably problematic that you're not staying long enough in a single cell tower's range, and doppler effects on the radio signals will also cause problems (if I remember correctly from my uni course on the subject).