The evaluation of high reliability in an autonomous decentralized IC card ticket system

Both high performance and high reliability are necessary for the automatic fare collection system. The IC card ticket system, developed in order to improve the passengers' satisfaction and to reduce the maintenance costs, cannot avoid the requirements, either. However, this new system has a problem; high performance on wireless communications lowers reliability. The solutions are the "autonomous decentralized architecture," the "autonomous decentralized algorithm," and the "autonomous decentralized data consistency technology." This paper introduces the "autonomous decentralized data consistency technology" for high reliability and evaluates the effectiveness by the functional reliability, which depends on how many times this technology runs and how many data the IC card contains. The results show the decentralized processes competitive to the centralized processes under the particular conditions. These conditions are made use of the practical "Suica" system at East Japan Railway Company and the system is running satisfactorily, without any fatal errors.