METHOD AND APPARATUS FOR TIME OR FREQUENCY SYNCHRONIZATION IN NON-GEOSYNCHRONOUS SATELLITE COMMUNICATION SYSTEMS

摘要

Method and apparatus for time or frequency synchronization of radio signals transmitted by user terminals in communication with a gateway through a satellite is provided. The satellite may be part of a non-synchronous satellite communication system, such as a low-earth orbit (LEO) satellite communication system for data, voice or video communications. Times of transmission of return link radio signals from the user terminals may be adjusted such that the signals arrive at the satellite or at the gateway without large time delay differentials. Carrier frequencies of return link radio signals transmitted from the user terminals may be adjusted such that the signals arrive at the satellite or at the gateway without large frequency offset differentials.