Error-Correction Coding for Digital Communications
Error-Correction Coding for Digital Communications
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Some sixteen proposed new satellite systems operating in the Q- (36-46 GHz) and V- (46-56 GHz) bands have been proposed to the FCC by United States companies. Of these, fourteen are intended to provide a global, or nearly-global, service. One is for United States domestic service and one is a package to provide additional store-and-forward capability on an earlier proposed ‘Little LEO’ system. This paper provides a brief description of the fourteen global systems which, for the most part, are designed to exploit the wide band of frequencies available for services such as multimedia distribution and Internet access. Systems are proposed that would use geostationary, medium-earth orbit, low-earth orbit, and Molniya orbit satellites, and in some cases, combinations of two of these orbits. Most of these new systems propose to exploit new technologies such as multiple narrow spot-beam antennas, on-board demodulation and routing of traffic between beams, intersatellite-links and in some cases, the scanning of the beams to continuously illuminate the service area as the satellite flies by. The paper discusses some of the difficulties of fielding systems at these high frequencies arising out of the propagation impairments that can be expected and the high cost of solid-state power devices for user terminals, which will drive up costs. It is concluded that while the large amount of bandwidth (3 GHz) that has been proposed by the FCC for these systems is attractive, few, if any, are likely to be built while spectrum remains available at Ka-band.