As trains speed past the forests and fields of the countryside they are often distant from the mobile network towers serving residential areas. Signals fall off and service breaks up.
Mobile net connection speeds on trains can also plummet on high-traffic routes between major cities when hundreds of users are simultaneously switched to a new network cell.
Passengers tend to blame the open onboard wifi network provided by the state railways VR. However, VR networks are reliant on the signal available from mobile network operators along its routes.
During the last round of licensing for the construction of 4G networks, one condition stipulated by the Finnish government was that all rail lines should have full signal coverage no later than by February 2020.
There are three owner-operators of mobile networks in Finland - DNA, Elisa and Telia. Their operations are concentrated in residential areas, and the provision of their licenses concerning coverage along rail lines, even in remote, scarcely-populated areas is a hit on their bottom line.
All three have taken the same position on the issue. They agree that network coverage along rail routes is important. On the other hand, they also say that significantly better data services for rail passengers would cost tens or even hundreds of millions of euros.
"Use onboard trains is still a relatively small part of total volume," DNA's Radio Network Director Jarkko Laari told Yle. "Upgrading all this infrastructure to get the same kind of data services as are available in an urban areas nowadays is in practice an unreasonably big endeavour."
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While the terms of their licenses obligate them to upgrade services for rail passengers, the Finnish Transport and Communications agency Traficom has not determined what the required minimum signal quality will be.
"Setting absolute numbers for a mobile network is very challenging. The quality of services for vehicles is also affected by many external factors, such as how many concurrent users there are," Traficom specialist Ritva Suurnäkki pointed out.
VR has invited the mobile network operators to start talks on upgrading data services for its passengers later this month.