Telia last week recorded record at download speed in tunnel. With 560 megabits per second, train passengers in the future can enjoy great mobile speeds on the journey, also on stretches where a lot of passengers travel.
The mobile network in the old rail tunnels does not manage to meet passengers' need for coverage and capacity on mobile data. On trains with very many passengers it is difficult to get good customer experiences, and therefore the Ministry of Transport and Communications has allocated funds to improve coverage and transmission rates for mobile data in tunnels on these routes.
"Telia, in cooperation with Bane NOR, has developed a pilot to show how this can be solved using technology that provides really good speeds, which can be used in all rail tunnels," says Dag Wigum, Technical Director of Telia Norway. - We have built 4G+ with two tapes, in this case 1800 MHz and 2600 MHz. Each of these bands has four currents, ie eight streams in total. It provides a capacity and speed in the network that should meet passengers' needs to do what they want to do on board a full train, whether it's working, downloading movies, listening to music or reading up on news.
Building 4x4 MIMO was a central discussion in the development of Follobanen, which opens in 2021. The Follo Line is a future new double track between Oslo Central Station and Ski Station. The double track will cover the need for increased capacity for train passengers traveling through the "Sørkorridoren", the transport corridor south from Oslo via Akershus and Østfold. Project Director in the Follo Line, Per David Borenstein, is very pleased with what Telia and Bane NOR have achieved in the Folloban project:
"This is impressive work, and Bane NOR and the Folloban Project are looking forward to offering a high-speed mobile network to our future train passengers. Now we are building a mobile facility with capacity that will provide good mobile coverage for full trains. In addition, trainers will experience stable and satisfactory mobile and internet coverage inside the tunnel, "said the project director.
Can achieve 800 Mb / s
The test was carried out in the Holmestrandtunnel in Vestfold, where Telia and Bane NOR have installed a 4X4 MIMO test system with beam cables. Generally, two antennae are built on 4G, but four beam cables are connected to the base station. Telia has expanded its existing base station in Holmestrandport to cover more of the old road tunnel. The result is record-high download speeds:
"With 560 megabits per second, we've set world records in speed in a tunnel," said Wigum. "Here we are in a tunnel with four beam cables instead of antennas, and so far we know never done on a full-scale road tunnel before any place in the world.
The test facility was built as a collaboration between Telia, Bane NOR and RFS, and last week there was a technical review of the facility. The measurements reached 580 megabits per second, but could be even higher:
"Now there is light inside the tunnel, and we can now achieve speeds of 700-800 megabits per second," says Wigum. "What we have tested now works very well for building high-speed mobile internet in rail tunnels where a lot of people travel. We are in dialogue with the other players, and in the long term it will be possible to have this solution also in Romanian sports and other tunnels in Norway. The new trains rolled out in Norway now have 4G repeaters, which makes the signal reception in the carriages much better and really increases the user experience.
About the test - for the technically interested
- The test was done with 4x4 MIMO Huawei radios on 20 MHz LTE1800 and 20 MHz LTE2600
- Four RFS beam cables were used: one cable on each side with vertical polarization and one on each side with horizontal polarization
- The tests were taken both stagnant at fixed points and at different speeds
- The phones used were Sony XZ Premium with 64 QAM and Sony XZ1 with 256 QAM.
- The results show that Telia achieves approximately 95 percent of theoretical maximum speeds of 4x4 MIMO in tunnel on one and one band
- The results also show that we have approximately 100% increase in rates from base station to phone when we go from SISO to 2x2 MIMO and from 2x2 MIMO to 4x4 MIMO
- Telia plans to test further with other phones to achieve even higher speeds