Mobile Satellite Communications Handbook, 2nd Edition

Chapter 7Low Earth Orbit (LEO) Mobile Satellite Communications Systems

7.1 Methodology

Although it is the largest and best known, Inmarsat is by no means the only commercial mobile satellite communications system in service. To fully understand the other commercial mobile satellite systems in service, we examine them in the next three chapters. Chapter 7 examines commercial low earth orbiting mobile communications satellite systems; Chapter 8 examines commercial geostationary mobile communications satellite systems; and Chapter 9 examines other significant commercial mobile satellite communications systems. Before doing so, however, it is worth a few moments explaining why and how the next two chapters are organized.

There are a variety of ways to organize any study of communications satellites that are used for mobile applications. Sometimes, they are segmented by the orbital type. As we have seen earlier, there are four principal orbits used by all types of artificial earth orbiting satellites: geostationary (GEO, geosynchronous equatorial orbit), low earth orbiting (LEO), medium earth orbiting (MEO), and elliptically orbiting (EO).

Some reviews of mobile communications satellites are organized by the frequency bands that are used for the satellite-to-mobile and for the mobile-to-satellite links (as opposed to the frequencies used for the links between the satellite and the ground station or hub). Earlier, we have seen that the L-band and, to a lesser extent, the S-band have ...