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Issue No. 02 - February (1997 vol. 30)
ISSN: 0018-9162
pp: 44-52
<p>Demand for sophisticated personal communication services has changed communications satellite design. Satellites have moved closer to the Earth to improve communication speed and enable personal communication services. But in so doing, they require more computing resources and more sophisticated protocols to handle intersatellite communications. </p> <p>Satellites have been used for decades, for weather forecasting, navigation, reconnaissance, and communications, among other things. Until recently, however, constraints on power, weight, and volume have made a spacecraft's computing resources so minimal that little emphasis has been placed on satellite communications and networking techniques. Now, however, this kind of support is in demand for use in today's sophisticated personal communication services. </p> <p>Increased demand for these services, coupled with advances in technology, has changed approaches to satellite design. The mindset of satellite systems designers over the past 30 years has been to keep complexity on the ground. Among other reasons, this minimizes catastrophic system failures should something happen to the satellite. Today, however, economies of scale have made possible the deployment of larger satellite constellations that can tolerate the failure of one or more satellites. Satellite orbits have also moved closer to the Earth, improving communication speed and enabling PCS services. But in moving to lower orbits, these next-generation systems have increased on-board complexity as satellites must now perform multiple satellite handovers to provide continuous coverage of the Earth. Thus, increased amounts of on-board computing resources and more sophisticated communication protocols must address the resulting increase in complexity. </p> <p>This article examines the trends in communications satellite deployment and the resulting requirements for network protocols that are intended to support space communications. We report the findings of a joint DoD/NASA effort to identify what parts of the seven-layer OSI protocol model can be adapted to support more sophisticated space applications; a global standard based on these findings is now under development. </p>

G. Comparetto and R. Ramirez, "Trends in Mobile Satellite Technology," in Computer, vol. 30, no. , pp. 44-52, 1997.
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