Performance study of ZigBee networks in a rail environment for signalling systems

Abstract

Railway signaling systems have the function of controlling the movement of rolling stock on the railway network without compromising security. Nowadays, signaling systems in operation in the U.K., rely on a physical interconnection grid for power supplying and data transferring, causing a high cost of implementation and maintenance related to infrastructure. In a previous paper [1], a ZigBee-based network was proposed as a modular low power wireless alternative for railway signaling systems, and studied in a synthetic environment created in a reverberation chamber (RC) in presence of realistic sources of EM interference. The performance of the ZigBee modules used, shown a persistent communication even in presence of high sources of interference, allowing the transference of information. Based on the previous, a complete multi-node signaling system was designed and implemented. In this paper, the performance of a low power communication system is studied and measured in a realistic environment where multiple elements such as rolling stock, power lines, and sources of interference are present. Additionally, the utilization of radio-frequency identification (RFID) technology has been included as part of train detection system, essential to control the movements of rolling stock, restricted by the Limit of Movement Authorities (LMA), which are a set of rules to keep coordination among the railway network and avoid collisions. Whilst a fuller knowledge of train location may allow train operators to allocate a greater number of rolling stock on the same railway network the adoption of the RFID tagging of items of rolling stock may be used in the wider context of asset management.