Multi-layered Data Consistency Technology, An Enhanced Autonomous Decentralized Data Consistency Technology for IC Card Ticket System

Service continuity, high performance, and high reliability are required in automatic fare collection systems. To comply with these requirements, the autonomous decentralized architecture has been introduced to the IC (integrated circuit) card ticket system. Based on the architecture, two technologies have been implemented: \´autonomous decentralized fare calculation algorithm" for high performance and "autonomous decentralized data consistency technology"for high reliability. This paper introduces "multi-layered data consistency technology." This technology enhances the autonomous decentralized data consistency technology by piling up the processes at each layer of nodes configured in the system. Various configurations with various intervals are simulated to determine the appropriate settings for optimization. The settings are used in the practical "Suica" system at East Japan Railway Company, and the system has been running satisfactorily, without any fatal errors.