An Innovative Multi-Port LoRa-Based Wireless Node for Railway Signaling and Positioning

This work presents the design and validation of a compact wireless system, adopting a modular wireless system composed of three co-located antennas operating in the 2.4 GHz band. The system is designed to be exploited for positioning purposes in secondary railway lines where the European railway traffic management system (ERTMS) is not available. An omnidirectional antenna, cross-polarized with respect to the other two, is used for transferring positioning data among the train and intelligent poles placed along the railway, while two directional radiating elements are arranged back-to-back, to perform wagon-to-wagon communication for train integrity purposes. The omnidirectional antenna has a radiation efficiency of 97.8% and a gain of 4.2 dBi, whereas the directive ones have 79.3% and 5.4 dBi, respectively. The data communication is established by using LoRa systems, enabling low-power, long-range communication with acceptable latency for the application purpose. Due to possible adverse environmental conditions, such as presence of dust or ice, a suitable enclosure of the system is designed to be as much as possible electromagnetically transparent. The whole system has been tested both in laboratory environment and on board of the moving train, inside and outside the wagon, demonstrating the successful communication between wagons and with the poles located along the railway. The highest bit error rate monitored was
$2.08\times 10{^{\text {-4}}}$
in the worst testing configuration.