Where do trains (and other moving things) get their interenet from?
July 16, 2014 5:43 AM   Subscribe

I know cell phone providers sell data plans, but my understanding is that these have limited connection speeds - these days many trains offer "free wi-fi" for the passengers (I was even told of a shuttle bus that had wi-fi available). It can't just be standard cell phone data connection right? That would be hopelessly slow if more than a couple of passengers connected. Planes use satellite connections I think. What technology do land based - but moving - wi-fi hotspots use? Thanks
posted by Xhris to Technology (9 answers total) 5 users marked this as a favorite
Actually, Amtrak does use regular cell service, which is why connection speeds for each individual user are very slow, but it wants to upgrade.
posted by Mr.Know-it-some at 5:49 AM on July 16, 2014

Aircell is a popular option for business jets. Looks like they have three connection options - Inmarsat, some other unnamed Ku-band satellite system, and a proprietary air-to-ground system that sounds very similar to cell service.
posted by backseatpilot at 5:56 AM on July 16, 2014

I was looking this up the other day as my bus now has free WiFi and found this link which provides a brief explanation of how one company is doing it (UK based):


Anecdotally, on my bus journey it seems to work so slowly that it is barely worth trying to connect, and it is much faster to use 4g if available.
posted by threetwentytwo at 6:43 AM on July 16, 2014

WiMax and 4G delivered wirelessly.
posted by KokuRyu at 7:24 AM on July 16, 2014

I know that years back the UK track manager was running dark fibre whenever they did track work, basically on the expectation that it'll come in handy some day. I wonder if that's being put to use now.
posted by Leon at 7:32 AM on July 16, 2014

Expanding on what KokuRyu said: www.yoursinglepoint.com/public-transit-internet.html
posted by Dansaman at 7:57 AM on July 16, 2014

The Van Galder buses (Madison-Chicago) use WiRover, which is being developed here at UW. You wouldn't mistake it for home internet, but it works reasonably well; roughly comparable to the GoGoInflight you can get on a plane, if you've ever tried that.
posted by escabeche at 8:09 AM on July 16, 2014

Trains can use standard cellular networks without being limited to the speeds an individual cell-phone or tablet user gets.

The actual transmission speeds over LTE allow downloads approaching 300Mbps. Whether or not the necessary equipment has been deployed to cellular base-stations is another matter. Even if it were, its unlikely that the wireless carriers would make the full capacity available to a single end-point (ie, the LTE data terminal on the train), since they also need to deliver a reasonable level of service to other customers in the area, but my understanding is that they can and do sell service at higher data rates to commercial customers. Moreover, I'd expect that it would be cheaper for them to deliver that service to amtrak than, say, flying surveillance drones, because trains run on fixed routes on predictable schedules, which simplifies capacity planning.

I'm not sure that Amtrak is buying this higher level of service, but I'd be surprised if they weren't.

I don't know if they do this or not, but they could get even more bandwidth by using directional antennas, each connected to a separate LTE terminal, to connect to multiple towers, when available, and distribute traffic between them. They could also connect to multiple carriers.

One of the major problems though is that, as the article linked above mentions, cellular coverage is still patchy and inconsistent. It is best in populated areas, and along major roads. Acceptable grades for highways vs rail is very different though, and so, often, the rails run far from main roads, often they go through narrow cuts, and sometimes tunnels, that block signals from ANY towers.

My experience with Amtrak WiFi on the Seattle/Portland corridor is uneven. Sometimes its great, other times it is poor or non-existent. When it is poor, I find that switching to tethering on my verizon iPad is better, because I'm not fighting with as many other people for bandwidth, but still not great, because the bandwidth is limited in the first-place because the cellular signal is weak in the first place. I notice thought that many times when the train and iPad connections are bad or non-existent, my phone has a better connection on AT&T.
posted by Good Brain at 1:13 PM on July 16, 2014 [1 favorite]

The Morgantown PRT uses a system based on the "white spaces" left behind by analog TV stations. It's easier to do custom solutions when your deployment radius is small.
posted by RobotVoodooPower at 2:53 PM on July 16, 2014

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