Institute for Telecommunication Sciences
the research laboratory of the National Telecommunications and Information Administration

William A. Kissick; David A. Sutherland Jr.; Marjorie L. Weibel; Wayne McCoy; Mary Ruhl; Robert Toense; Udayan Borkar; Moorthy Hariharan

Abstract: Many government telecommunications needs, especially those that support National Security and Emergency Preparedness (NS/EP) missions, are becoming increasingly dependent on commercially available equipment and services. This is consistent with the goals and concepts of the National Information Infrastructure. This report examines the use of an advanced satellite–in this case, NASA's Advanced Communications Technology Satellite (ACTS)–with ISDN and frame relay protocols to support NS/EP communications requirements. A network using three ACTS Earth stations was established as a research facility. With this small network, several experiments were performed. Using new objective methods, voice quality was measured over the satellite and compared to other connections such as commercial, terrestrial lines. The performance of applications–desktop conferencing, file transfer, and LAN bridging–that are likely to be useful in NS/EP situations, was determined. The performance of TCP/IP running over frame relay was examined. The results indicate that advanced satellites can be very useful for emergency communications due to the rapidity that Earth stations can be deployed, the ease of reconfiguring the satellite, and the practicality of using commonly available applications running over commonly used protocols. However, there are some limitations to the performance of some applications or parts of applications due to the propagation delay of a satellite channel. Telecommunications protocols such as TCP/IP must be significantly modified to perform well over a satellite channel and to take full advantage of bandwidth–on–demand capabilities of an advanced satellite.

Keywords: Integrated Services Digital Network (ISDN); advanced communications technology satellites (ACTS); frame relay; National Security and Emergency Preparedness (NS/EP)

To request a reprint of this report, contact:

Lilli Segre, Publications Officer
Institute for Telecommunication Sciences
(303) 497-3572

Disclaimer: Certain commercial equipment, components, and software may be identified in this report to specify adequately the technical aspects of the reported results. In no case does such identification imply recommendation or endorsement by the National Telecommunications and Information Administration, nor does it imply that the equipment or software identified is necessarily the best available for the particular application or uses.

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