A TST/SS-TDMA telecommunications system - From cable to switchboard in the sky

To maintain sufficient connectivity in a Time-Division Multiple Access (TDMA) network using satellites with multiple-beam antennas, it is essential to introduce a switching function onboard the spacecraft. The usual solution is a switching matrix either at intermediate frequency or at baseband. An SS-TDMA is in effect a Time-Space-Time (TST) switching center in which the satellite performs the space switching function only. This paper describes a system based on a more advanced concept in which the satellite performs the entire TST switching function. The increased complexity of the satellite payload is countered by a dramatic reduction in the complexity of the Traffic-Terminal equipment at the earth stations. Furthermore, it is shown that this concept has a number of advantages in the areas of frame efficiency, onboard bit-rate conversion, demand assignment and for incorporation with an Integrated Services Digital Network (ISDN).