A performance analysis of the IRIDIUM® low earth orbit satellite system with a degraded satellite constellation

Abstract

There are currently several commercial Low Earth Orbit (LEO) satellite systems under development that will provide worldwide voice, data, facsimile, and paging services. This article presents a performance analysis of the IRIDIUM® LEO satellite system, as several satellites become non-operational. The analysis is conducted using a computer simulation of the system. First, it examines the system's capability to meet real-time communications constraints of end-to-end delay and packet rejection rate with non-operational satellites. Then, it examines the effects of these non-operational satellites on a user's ability to access the network. The analysis is conducted at low, medium and high traffic loading levels with both uniform and non-uniform traffic distributions. The results indicate that the IRIDIUM® system is capable of providing real-time voice communications with several non-operational satellites. Both the loading level and the traffic distribution have a significant effect on the performance of the system.