Software-reliability evaluation of the TROPICO-R switching system

The analysis and evaluation of the software of the TROPICO-R switching system are described. Failure data were collected over 27 months, including validation phase, field trial phase, and operational life. During this period 461 failure reports have been recorded. Two models (exponential and S-shaped) have been applied to these failure data, and have been analyzed according to their repetitive and predictive capabilities. It is found that it is difficult for the models to reproduce the observed failure data when changes in trend do not follow the model assumptions. The Laplace trend test is a major tool for guiding the partitioning of failure data according to the assumptions of model reliability growth. Only the S-shaped model has been considered for the analysis according to trend periods. Prediction yields good results over a time period of a few months, showing that reliability modeling is a major tool for test/maintenance planning and follow-up