ABSTRACT
Communication satellite systems designed to serve the mobile user community have long held the promise of extending familiar handheld cellular communication to anywhere a traveler might find himself. One impetus to the fulfillment of this dream has been the success of the Inmarsat system of communication satellites. Founded in 1979 as an international consortium of signatories, Inmarsat provides worldwide communication services to portable and transportable terminals, thereby meeting one of its mandates by enhancing safety on the high seas and other remote areas. Although it does not support handheld, cellularlike operations (due to limitations in the satellite design), the current Inmarsat system is a successful business. Clearly, the next logical step would be to enhance the capabilities of the space segment to provide cell phone utility with even greater ubiquity than available terrestrially. What we would then accomplish is to, essentially, raise the familiar cellular base station several hundreds of kilometers high and, thereby, extend the coverage many times over (see Figure 11.1).
