Go Fly a Blimp

European wireless editor Guy Kewney looks skyward for a Wi-Fi solution for travellers.

Question: How many 802.11 wireless transceivers would it take to cover a 50-mile stretch of road?

Answer: Only one, if its a railroad. Just put the transceiver in the train. Then fly a plane with broadband microwave on board just above the train.

No, I aint kidding.

Daunted by the capital cost of trying to get Wi-Fi to travellers, the worlds ISPs are starting with rail commuters. And to reach train riders, some of the tricks they are getting up to are starkly unbelievable.

Fitting a Wi-Fi access point to a train is relatively simple. Theres plenty of electricity with no anxieties about battery life. Signal propagation, inside a metal tube, is usually excellent. The train almost acts as a wave-guide. The problem is that train commuters arent really interested in networking with each other. They want access to the outside Internet world, and thats really quite a challenge.

The first, obvious trick is to stick an antenna on the train to track a satellite. In really flat countries around the equator this works flawlessly. But move out of the tropics and into hilly country or urban areas and the satellite is often lost below the horizon. Europeans, as a result, dont think much of geostationary satellites. You can never see one when you really need it.

The result is that theres an amazing amount of interest in low earth orbit wireless, or LEOs as they are called, and in other even wackier ideas. Tethered aerostats--big balloons--are being experimented with, but the Capanina project is going way beyond that, and looking for other ways to get an antenna into the sky without launching a satellite. Furthermore, in London last week, the surprise star of the conference on "Practical Strategies for Implementing Wi-Fi in Passenger Transport," was North American railroad pioneer, Pointshot, which is already providing Canadian and Californian rail commuters with free Wi-Fi and moving into the area of wanting to start asking them for real money.