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SIGNALLING & TELECOMS
PAUL DARLINGTON
RAIL 5G PRIVATE OR PUBLIC NETWORKS?
PHOTO: DAVID PRADO
M
obile internet connectivity on trains is now the expectation of most passengers. Data connectivity is also now essential for railway operations and maintenance, and will be even more important for in-cab signalling. But providing reliable cost-effective radio connectivity is not easy. It is like trying to guarantee continuous communications and of sufficient capacity for a moving street, and to a device located in a Faraday Cage - a metal box and barrier to electromagnetic signals. There are solutions such as onboard antennas, amplifiers and distribution, low signal-loss windows, and more fixed radio and/or Wi-Fi sites, but all at a cost. Issues such as intermittent performance, dropped connections, slow data performance, blocking and handover at fast linespeeds are all too common. The systems must be designed for short bursts of high-capacity data demand and then little demand as the train moves along the line. A reliable internet connection service, all along a train route, requires a large investment. The traffic will be relatively low usage when averaged out compared to a commercial radio network.
Rail Engineer | Issue 189 | Mar-Apr 2021
Built on 5G Radio systems can be private closed systems, such as the current GSM-R system for operational purposes, or public commercial systems operated by Mobile Network Operators (MNOs). It is MNOs who mostly provide the passenger internet experience today, via onboard Wi-Fi systems, supplemented with fixed Wi-Fi connections. MNOs want to sell data, streaming and voice services anywhere they reasonably can. Train operators and governments want to provide gigabit speeds for passengers, but how is it going to be funded? What level of train connectivity coverage is economically and technical feasible? The current GSM-R system has a huge number of radio sites located trackside, but carries relatively little radio traffic compared to MNO systems. GSM-R is a huge national asset which cost in the order of £500m plus fibre costs, and while it has been very successful for rail operations, could the investment of thousands of radio sites and connecting fibre be put to better use for railway operational purposes and passenger use? The Future Railway Mobile Communication System (FRMCS) is the future worldwide telecoms system designed by the UIC (the worldwide professional railway association) and will be based on the 5G standard. FRMCS is intended to be another private network and the successor to GSM-R for operational communications, but it will also have the capability to provide mobile connectivity for passengers. FRMCS is not likely to be rolled out for some time and it is not clear how it will be funded as the costs will be huge.
