Broadband internet on trains - how does it work?

Question

Several train companies in the UK (and elsewhere I presume) now offer wireless internet on board.

I regularly use the internet on board GNER trains, and although it is very slow and regularly disconnects it is still useful.

I am curious to know how the moving train is able to connect to the internet? Does it involve some kind of satellite connection, or the mobile phone network, or is the signal sent down the overheard power lines?

Also I forgot to mention that it always stops working in stations - these have a roof which could be blocking the satellite signal?

Answer 1

It is either Satelite or Tower Transfer, I doubt it is Mobile phone but it could be.
When you say it looses the signal leads me to believe they are getting and loosing there signal via Microwave Tower, or Satalite dish on the train.
Don

Answer 2

there are many ways to provide wifi on train.

1 - satellite
This is the most expensive method but essentially the train has a satellite unit and connects to a wifi access point.

2- mobile internet using 3G, HSDPA, EVDO, EDGE
these are common internet protocol found on cell phone. instead of a satellite unit, these industrial grade "cell phone" talks with the cell phone signal tower. these are cheaper than the satellite since the charge per KB is lower.

3- fast roaming wifi
some operator has installed wifi unit along the rail track. But since the train is moving pretty fast, a special wifi router is used to talk with these wifi access point and then broadcast back into the train. something like this pepwave mobility

http://www.pepwave.com/products/mobility/

while it cost a lot to setup these internet backbone, but there are no monthly usage charge like the satellite or edge based method.

Answer 3

Ask one of the conductors or other train staff - no doubt they know.