Railway communication technologies undergo a revolutionary change bringing them from the analog to the digital era. The European Rail Traffic Management System (ERTMS) replaces numerous incompatible analog radio systems, classical side-track signs and legacy in-cab signaling with an integrated comprehensive solution.
This paper presents an overview of GSM-Railways (GSM-R), which is the unified communication technology supporting ERTMS. Its shortcoming in terms of capacity and capability are discussed as a foundation for the need for further developments.