ARCHIMEDES-land mobile communications from highly inclined satellite orbits

A satellite based European land mobile system overcomes the main cellular radio problem of limited coverage by covering the entire continent, both highly and sparsely populated areas, from the outset. Conventional geostationary satellites suffer from high fades due to signal blockage by roadside trees and buildings at low elevation angles. Another disadvantage is the need for a costly and bulky antenna pointing mechanism on the mobile if voice quality services are to be offered. The ARCHIMEDES study aims to overcome these problems by using a system of satellites in highly inclined elliptical orbits, which appear at high elevation angles over Europe for a significant portion of their orbits. By using a number of such satellites, continuous coverage of Europe can be achieved at high elevation angles. The author describes the current ARCHIMEDES system design and explains how the problems associated with the communications performance of the system are overcome