The cost per billable minute is the metric to compare the efficiency of different mobile satellite system architectures. The cost per billable minute to achieve a specified rate of return is determined from estimates of the useful system capacity and life cycle costs, To evaluate the useful system capacity, a computer simulation was developed to model the complex interaction between satellites, gateways, capacity limits, and an expected market model. The major capacity limiting factors addressed include frequency reuse, constellation design, link availability, spotbeam patterns, multiple access schemes, and satellite power, The life cycle costs were estimated for the satellites, launch vehicles, gateways, public switched telephone network hardware connections, operations, and launch insurance, The metric is evaluated for six model systems in low, medium, and geostationary Earth orbits to demonstrate the usefulness of the metric in the design process.
