DOUBLING THE CAPACITY OF A COMMUNICATIONS-SATELLITE SYSTEM

Two one-way channels are normally used in digital two-way voice commun ication. Each channel is in effect used only one half the time. A rece nt discovery of ours recognized that any one-way channel within a sate llite spot-beam can be accessed by anyone in the footprint of the beam . In a two-way voice call, the two parties alternate (in principle) in their transmissions - when one speaks the other is silent. Therefore, the two can share a single one-way channel and provide continuous use of the channel, their respective transmissions interleaved with one a nother. This condition is unique to intrabeam communication via satell ite (or balloon). In a satellite system, capacity is a valued commodit y, where capacity is limited by allocated bandwidth and power availabl e. Under those two constraints of bandwidth and power limitation, the discovery described generates a doubling of capacity. This article add resses this concept and some of the engineering challenges and opportu nities arising therefrom.