If you have already taken advantage of a train trip to try to work or launch a streaming movie on your computer, you have necessarily experienced the frustration that goes with it. Although it is indicated that Wi-Fi is available on board, the connection does not work well: either it is impossible to have access to the network, or the pages take an infinite time to load, or the untimely disconnections are linked.
May users of French trains be reassured: they are not the only ones want to tear their hair when trying to use the Wi-Fi offered in their TGV or their TER. This is what politico shows with an article devoted to the deplorable quality of the Internet connection in all European trains. It would also seem that it is not about to improve.
Doppler and Faraday
You could expect it: if it is difficult to maintain a stable connection in the trains, it is first because of their high speed, which creates a doppler effect. Imagine that you move along a constellated path of Wi-Fi terminals to which you have access: as you advance, your smartphone or your computer will connect to the closest to them, so disconnect from the previous one. In terms of stability, it is hell. It’s a bit of what is happening with the trains, but several hundred kilometers per hour.
“If a train runs at 200 km/h, the device could cross a cellular station every 45 or 60 seconds, which represents a rapid rotation”explains Luke Kehoe, industrial analyst at Ookla, an intelligence company on connectivity. Quick displacement modifies the signal frequency (as when a siren changes its height) and can disrupt the ability to maintain a stable connection. But the speed and number of relay antennas (sometimes insufficient) are not enough to explain the extent of the phenomenon.
It turns out that many train cars are simply not designed to let the radio frequencies pass. “Historically, many trains used windows with coatings in metallic glass or low emissivity, intrinsically little conducive to the propagation of the signal”indicates Luke Kehoe. When you take a seat on the train, you generally find yourself in a Faraday cage, name given to these electromagnetic armor which completely blocks wireless signals-as when your microwave prevents radiation from escaping.
European trains have a hard time providing reliable Wi-Fi, even if some countries achieve it better than others. It is in Switzerland that the connection is the best: it is the only European country in which we exceed 25 megabits per second in median download speed, which is the minimum threshold for reliable use of the Internet. The Czech Republic follows and … France, which is still third – which is very revealing of general mediocrity.
Modernization is underway, but it is very expensive and requires extensive experiments. The Czech Railways Czechs are currently testing Elon Musk’s Starlink network, which seems to be successful, while the SNCF would hesitate between their follow-up and start collaboration with the Franco-British of Eutelsat. Let us recall in passing that if politico’s article only evokes European trains, it is because this media is entirely devoted to our continent. It is very likely that the problems of rail wi-fi are just as important in the other areas of our planet.
