Train automation can be divided into control and operations. Both types consist of distributed applications that rely on dependable communication. Typically, control applications such as for automated train control are of higher priority than operational applications, and the latter are typically of higher priority than passenger services. One of the main challenges is to guarantee the premium priority of control-related communication over other types of communication, especially since the data bandwidth consumed for control is typically dwarfed by data traffic stemming from the other two application areas. Another challenge is to guarantee the super priority of operational data communication over passenger-related communication. Driverless trains are not the only source of automation in mass transit, and thus not the only source of dependable machine-type communication. For instance, mass transit train control (MTTC) including communication-based train control (CBTC) is also used for trains exhibiting lower grades of automation, if assisted by rail-to-rail-side wireless communication, which is at the core of driverless trains.
Communication services for MTTC have to coexist with other high-priority and low-priority communication services. This coexistence is done assigning priorities to the communications, see below an example of how these priorities can be allocated:
The MTTC communication service might have the highest priority (train control).
The CCTV communication service might have high-priority, but lower than MTTC.
(High data rate) data communication services such as passenger internet access might be of low priority.
Emergency calls need to be established on demand with a priority suitable to guarantee call success independent of already running communication services.
NOTE: This kind of emergency calls is using the train and rail infrastructure and not the public emergency services. An example for a train emergency system are microphone/speaker boxes that are integrated into the walls of the passenger area.
The setup of high data rate communication services with low priority does not have an impact on the communication services for train control. Furthermore, the start-up of a communication service for train control will acquire sufficient resources in the 5G network, even if high data rate communication services with low priority are already running.