Satellites and the ISDN

The potential role of satellites in an integrated services digital network (ISDN) is discussed in the light of recent CCITT studies. Present satellite digital-communication techniques are reviewed, and the changes introduced by ISDN development and by the competition of long-distance optical-fiber networks are characterized. CCITT standards on error performance (e.g., bit-error rate less than 10 to the -6th for at least 98 percent of the worst month), availability, and synchronization are summarized and compared with currently applied satellite standards. Since the potential for improvements in transmission quality and delay in satellite systems is limited, it is recommended that satellite planning concentrate on transparency enhancement (including speech processing, frame-format modification, and forward error correction) to accommodate ISDN.