The Prediction of Rare Propagation Events:the Changing Face of Outage Risk Assessment in Satellite Services

Telecommunications systems have evolved from the analog world to the digital world in two decades. This is particularly true for all categories of commercial satellite service: fixed, mobile, or broadcast. In the field of radiowave propagation modeling, however, the transition from the analog era to the digital era has been somewhat slower. Forcing the pace of propagation modeling has been the evolution, and then rapid expansion, of digital services for the end user. These might be packet or circuit switched; connection-oriented or connectionless; IP based or MPLS; and so on. How to define performance and availability when it is the throughput of un-errored bits that (literally) count? This paper looks at the origins of propagation modeling for satellite services and then recasts the approach in terms of the needs of the service providers and users in the digital age of the twenty-first century. It is seen that there are two very different propagation modeling requirements: one for high capacity terminals and one for low capacity terminals.