WirelessMoves: Satellite Internet on Thalys High Speed Trains

It's great when two high speed technologies come together: High speed trains running at over 300 km/h and high speed Internet access. Thalys, whose trains travel between Paris, Brussels, Amsterdam and Cologne has equipped all of their trains with satellite, Wi-Fi, UMTS and GPRS based high speed Internet access, accessible to passengers via standard Wi-Fi. When I recently traveled on one of those trains, I could hardly wait to get on board to test and use the system.

The picture on the left shows the satellite antenna installation on top of one of the coaches. It looks a bit odd on the otherwise very streamlined train but the round shape probably keeps the additional drag to a minimum. Nevertheless, I'd be interested in finding out how much extra energy is necessary to push the train beyond 300 km/h due to that.

At 7 a.m. in the morning, throughput in both uplink and downlink between Paris and Brussels was tremendous. Speedtest.net reported downlink speeds of more than 10 MBit/s and more than 3 MBit/s in uplink direction! While the link dropped a number of times on the trip to Brussels it was only for a few seconds each so that was probably only apparent to an attentive observer like me running a data trickle in the background to detect just such occurrences. However, the outages were short enough that it didn't affect streaming applications once enough data was buffered. Watching a Youtube video, full screen and in HD quality worked just fine.

As all data is transferred via a satellite in a geostationary orbit, round trip delay times were in the region of 650 ms. While voice calls and even Skype video calls work well over the system the delay can be felt in the conversation. Loading a graphics intensive web page works quite well and fast but it feels a bit sluggish for a moment after clicking on a link or entering a web address before the download of the page starts. This is again due to the very high round trip delay time compared to other systems such as ADSL with a round trip delay time of 50 ms, or the 120 ms over a 3G connection. Having said all that, the experience is still great, especially taking into account that the countryside is passing by at 300+ km/h when looking out of the window while that HD video is streamed over the satellite.

The satellite connection has one real several imitation: In Europe, the geostationary satellite hangs close to the horizon, so it is not always possible during the trip to keep the connection. In such cases a ground based backup is used. In the Brussels main station, for example, Wi-Fi is (probably) used. Downlink speeds came close to 16 MBit/s and round trip delay times were lower than 50 ms. The tunnels around Brussels were covered as well, although I was not sure exactly what technology was used. In other places, especially in the hilly terrain between Belgium and Germany, the satellite connection doesn't work too well either, probably because the train winds its way through narrow valleys and many tunnels. GPRS and UMTS network in that region seem to be patchy at best so the experience on that part of the track wasn't too great.

In between I should also mention that I didn't find any services that were blocked. VoIP worked well, IM worked well and my IPSec based VPN also worked fine over the system.

In the evening I made the same trip in the other direction. It seems a lot more people were using the system in the evening as speeds were much slower than in the early morning. While I could still reach fantastic transmission peaks of 3 MBit/s in downlink and more than 1 MBit/s in uplink, I experienced continuous high packet loss and frequent connection outages in the range of minutes even on the flat terrain between Brussels and Paris. The bad weather and heavy rain might also have had something to do with it, it's difficult to tell from a single ride.

Summary:

Of course I had my expectations before trying the system. In most cases I found it to be much faster than I expected. Especially the main applications such as web browsing, e-mail and VPN tunneling to the company network worked fine. The system has its limitations in hilly areas and cities when there is no direct line of sight to the satellite. While the system automatically switches to GPRS or UMTS in such cases, it didn't work particularly well in many of those places areas, as they were probably not covered very well. It can work much better over 3G as I have experienced here. Overall, however, I was very impressed with the system and I think it's a great service!

Comments

Did the VPN drop as the access networks changed?

Posted by: Ajay Sahai | June 03, 2009 at 08:40 PM

I guess I should be more specific - you say that the VPN stayed up, but my question is that because it was getting reconnected/buffered or the IP address was constant? Any ideas?

Posted by: Ajay Sahai | June 03, 2009 at 08:43 PM