Space segment for VSATS in Europe

Discusses the development of the `SMS Open User Network´ where the satellite transmission parameters and earth station characteristics are specified. The system is open to any user with an earth station conforming to the standards. The single channel per carrier (SCPC) frequency division multiple access (FDMA) technique used in the Open Network incorporates the necessary flexibility for sharing the SMS transponders between many different users. In addition to the Open Network, customer-tailored `SMS Closed User Networks´, for which transmission parameters and earth station characteristics would be defined by the users in line with their own requirements are also allowed to use the space segment. In closed networks, virtually any modulation or accessing technique can be accommodated, as well as a wide range of user bit rates, link qualities and earth segment configurations