Proposed U.S. Global satellite systems operating at Ka-Band

Abstract

In May 1997, the U.S. Federal Communications Commission (FCC) licensed 13 proposed new Ka-band (20-to 30-GHz) satellite systems. Twelve of these systems intend to use geostationary orbits, and the FCC has allocated 49 orbital locations for the 55 satellites proposed for these systems. The 13th system, known as Teledesic, was to employ 840 low earth orbit (LEG) satellites. Subsequently, Teledesic announced a redesign of its system to use 288 satellites, and Motorola filed for a LEO system to be known as Celestri, having 63 satellites. The proposals from the larger players (e.g., Hughes, Loral, Lockheed Martin, and Motorola) are all for global, or nearly global, systems. This paper summarizes these global systems and discusses some of the technical challenges that the designers of these systems must overcome, as well as the markets the new systems might be expected to serve. All of the Ka-band systems plan to use the 500-MHz bandwidth allocated for fixed satellite services, in accordance with the 1995 World Radiocommunications Conference (WRC-95) guidelines (29.5 to 30.0 GHz for uplink and 19.7 to 20.2 GHz for downlink). A majority of the systems will also use the 28.35-28.6/18.55-18.8 GHz (250-MHz) frequency bands. In addition, some of the systems use part or all of the 29.0-29.5/19.2-19.7 GHz frequency bands. These bands require coordination with local multipoint distribution services (LMDS) and/or mobile satellite services (MSS) feeder links. All but two of the announced global systems employ satellites in geostationary Earth orbit (GEO). All the Ka-band systems except Teledesic and Celestri are designed to cover land masses only. Teledesic proposes to cover the entire globe, including polar regions and oceans, while Celestri will cover all latitudes between /spl plusmn/60/spl deg/. The Astrolink and Galaxy/Spaceway systems cover virtually all land masses. Loral's Cyberstar, along with GE*Star and Morning Star, cover most of the major population centers or areas where rapid traffic growth is expected early in the next century.