Survey of Synchronization Techniques for a TDMA Satellite-Switched System

On-board processing of signals in a communications satellite system is rapidly becoming a reality. To meet the needs in high capacity systems, new technologies are being developed, and one of the most recent is the system called time-division multiple-access, satellite-switched (TDMA/SS) which employs multiple spot beam zones. Since TDMA is employed, it is necessary for all earth stations to synchronize their time bases to a common reference which, in this case, is the sync window connection of the satellite. Synchronization for this system is a major problem which has been examined in detail in a number of different papers. This paper provides a survey of the various techniques which have been proposed in the past and gives a comparative analysis of the advantages and disadvantages of each. Factors taken into account include timing accuracy, bit energy to noise density ratio of difference signals, estimated delay for acquiring acquisition, tracking features, microcomputer implementation, and possible improvements for the future.