Chinese Railway Uses Wi-Fi Spectrum for Signalling - with Predictable Results
Published on: 21st Nov 2012
Note -- this news article is more than a year old.
The decision by a Chinese railway to rely on the unlicensed 2.4Ghz radio spectrum band for its signalling systems has caused an entirely predictable effect.
The band is used by Wi-Fi hotspots, which are now interfering with its signalling network and shutting down the railways.
The problem has been exasperated by the use of portable Mi-Fi devices that allow a 3G signal to be shared by a portable Wi-Fi device. Experiments by the railway found that their signalling systems are affected when seven or eight wireless routers are carried into each carriage.
Shenzhen Metro has applied to the regulator to allow it to block the Wi-Fi hotspots, but that was refused.
Although the railways have been criticized for relying on the public Wi-Fi spectrum for their critical infrastructure, the difficulty in securing licensed radio spectrum from the regulator, that would be free of interference has also been blamed.
On the web: Caijing