The experiments are designed to test advanced concepts that will permit commercial use of such hybrid networks. ACTS was launched by NASA in September 1993. It is an experimental geostationary satellite and the first to have on-board processing capabilities. Its switchable spot beams concentrate power in relatively small areas on the Earth, and thus achieve bandwidth and power efficiency on a demand basis.
Hybrid networks integrate the technologies of satellite networks and terrestrial networks.
The experiments are based on a hybrid network architecture whereby a node may use both satellite and terrestrial links in obtaining a service from the network. These experiments go beyond traditional applications, which typically utilize satellite and terrestrial links as separate entities rather than as a single integrated system, according to Ephremides. These algorithms are designed to exploit the inherent advantages of either the satellite or terrestrial link for optimal performance. In addition to delay mitigation, a hybrid network also allows the use of a receive-only satellite station at the destination. Several graduate, undergraduate, and exchange students are participating in each experiment.