Measurement of reliability and availability of satellite communication links: Progress and challenges

The probability of correct operation of the system during a given lifetime is called the reliability. The reliability of a complete satellite communications system depends on the reliability of its two principal constituents - the satellite and the ground stations. The availability of a complete satellite communications system depends not only on the reliability of the constituents of the system but also on the probability of successful launching, the replacement time and the number of operational and back-up satellites (in orbit and on the ground). Availability of the ground stations depends not only on their reliability but also on their maintainability. For the satellite, availability depends only on reliability since maintenance is not envisaged with current techniques.