GIGABIT SATELLITE NETWORK FOR NASA ADVANCED COMMUNICATION TECHNOLOGY SATELLITE (ACTS)

The advanced communication technology satellite (ACTS) gigabit satelli te network provides long-haul point-to-point and point-to-multipoint f ull-duplex SONET services over NASA's ACTS, at rates up to 622 Mbit/s (SONET OC-12), with signal quality comparable to that obtained with te rrestrial fiber networks. Data multiplexing over the satellite is acco mplished using time-division multiple access' (TDMA) techniques coordi nated with the switching and beam hopping facilities provided by ACTS. Transmissions through the satellite are protected with Reed-Solomon e ncoding, providing virtually error-free transmission under most weathe r conditions. Unique to the system are a TDMA frame structure and sate llite synchronization mechanism that allow: (a) very efficient utiliza tion of the satellite capacity; (b) over-the-satellite closed-loop syn chronization of the network in configurations with up to 64 ground sta tions; and (c) ground station initial acquisition without collisions w ith existing signalling or data traffic. The user interfaces are compa tible with SONET standards, performing the function of conventional SO NET multiplexers and, as such, can be readily integrated with standard SONET fiber-based terrestrial networks. Management of the network is based upon the simple network management protocol (SNMP), and includes an over-the-satellite signalling network and backup terrestrial inter net (IF-based) connectivity. A description of the ground stations is a lso included.