Terminal System and Capability for ARPA-NASA High-Speed SONET/ATM Experiments Over NASA's Advanced Communications Technology Satellite

Gigabit Earth Stations (GESs) are under development for the ARPA-NASA Gigabit Satellite Network using NASA's Advanced Communications Technology Satellite (ACTS). The GESs will be equipped with SONET OC-3/3c (155.54 Mb/s) and SONET OC-12/12c (622.08 Mb/s) user interfaces. Through these interfaces SONET/ATM experimenters will be able to establish long-haul point-topoint and point-to-multipoint full-duplex OC-3/12 links via satellite. These links will have bit error rate performance comparable to fiber (BER < 10-11) using relatively small 3.4meter diameter antennas. Satellite channel sharing and synchronization with the ACTS on-board microwave switch matrix (MSM) and beam switching capabilities will be performed using Satellite-Switched Time Division Multiple Access (SS-TDMA) techniques, to be implemented within the GES's "Digital Terminal" subsystem. The Gigabit Earth Stations are being designed to perform the function of conventional SONET multiplexers and to be capable of integration with any standard SONET terrestrial network. As SONET multiplexers in the SONET hierarchy, the GESs will perform clock synchronization between geographicallyseparated end-user interfaces by terminating the section and line overheads of the SONET frames at the transmitting end of each satellite link, by transporting the payloads plus payloadpointer-bytes over the satellite, and by regenerating the SONET frames and corresponding section and line overheads at the receiving ends of the satellite links. The Gigabit Satellite Network will have provisions for remote monitoring and control, and statistics collection for SONET/ATM experimenter support. In order to make the system available to a variety of experimenters and to be able to reach points where terrestrial fiber may not be available, the Gigabit Earth Stations will be provided in transportable weather-protected configurations.