Frequency synchronization in global satellite communications systems

A frequency synchronization method is proposed and analyzed for global satellite communications systems employing low Earth orbit satellites or medium Earth orbit satellites. In these systems, the Doppler shift varies randomly and can be more than ten times larger than the symbol rate. The proposed method uses the satellite as the reference point and corrects frequency errors accordingly. It is shown the proposed method can achieve negligibly small frequency errors. By employing this method, the system bandwidth can be fully utilized and guard bands are no longer needed.