SS-TDMA SYSTEM CONSIDERATIONS

The INTELSAT VI satellite-switched time-division multiple access (SS-TDMA) system represents completion of the full cycle of the 120-Mbit/s TDMA system design that was first introduced operationally on an Atlantic Ocean Region INTELSAT V satellite in October 1985. The original design was intended for operation with static transponders, but contained all the features needed to graduate to dynamic switched operation. This paper describes how compatibility between static and dynamic switched operation was accomplished through the network control system design (including the SS-TDMA frame structure), acquisition and synchronization between earth and space segments, the structure of the traffic burst time plans, preparations for establishing the switch-state time plans, coordination and synchronization of the changing of the two time plans so that no ongoing traffic is disrupted (hitless time plan change), and plesiochronous interface operation and the related control of the on-board timing oscillator.