An approach to developing an infant mortality requirement for fiber optic transport systems

The approach used in developing an infant mortality requirement for fiber optic transport systems used in Bellcore client networks is described. Two generic parameters are considered: failure rate ratio, which is the ratio of the instantaneous failure rate to the steady-state failure rate, and infant mortality factor, which is the ratio of the expected number of failures in the first year of service to the expected number of failures in a steady-state year. Each of these parameters is discussed, and two methods of deriving a value for the infant mortality requirement are discussed. The first, a time-effective method, analyzes the infant mortality models to determine when there has been sufficient decay in the rate of change of the number of failures. The second, a cost-effective method, analyzes the models to determine a point at which overall costs are minimized