Robustness Study of ZigBee Networks in an EM Environment for Railway Signalling Systems

Railway signaling systems are used to efficiently control railway traffic to maximize the throughput of rolling stock on the railway network without compromising security and safety, allowing railway transportation operators to allocate a greater number of trains on the same track. Current U.K. signaling systems rely on a physical interconnection grid for power supplying and data transferring. Hence, a very high cost is related to infrastructure. Therefore, there is a need for a low cost, low power modular wireless system, able to be easily deployed and incorporated within existing signaling networks. In this paper, the study of a low cost, low power communication system is addressed. Sequentially, an alternative modular wireless solution is presented, based on ZigBee-Protocol, followed by a performance analysis tests, evaluated in terms of coverage, network throughput and data capacity, conducted in two different scenarios: an outdoor environment and in an synthetic environment created within a reverberation chamber in presence of realistic sources of electromagnetic interference. The results of these tests are used as guidelines to produce a wireless signaling system able to be placed on trackside, allowing node-to-node and node-to-train communication.