Shenzhen subway lines had to shut down 3G data service after trains stopped running unexpectedly because of telecommunication problems.
Shenzhen passengers were unable to use 3G data services yesterday at some lines because the frequency used by mobile devices is the same as the frequency used by the management system that operates Shenzhen Metro.
The cut down affected the Hangzhong and Shekou lines. The main problem is that both mobile devices and Shenzhen Metro operate on 2.4-gigahertz. So when too many passengers use data services, the interference caused by the volume of traffic causes the trains to stop operation out of a sudden.
The 3G suspension added to public concern that Shenzhen Metro would seek to permanently end mobile data services on the trains. The Sina Weibo microblogging service was buzzing with passenger complaints and opposition to any long-term disruption.The Shenzhen Metro company issued a brief statement on its own Weibo account at noon, saying that the suspension had been approved by the city government. It apologized for the inconvenience to passengers.
The transport company blames the emergence of portable Wi-fi routers, which allow consumers to create mobile wireless networks using a single 3G SIM card. It believes interference from the devices triggers the trains’ emergency brakes.
A long time solution for the problem would be to implement a new system on the metro that would use a different frequency band, it would then avoid any interference from mobile devices. This solution would take some time to be implemented due to the fact that all the metro stations in China operated under the same frequency band.
In Hong Kong, where the volume of traffic from mobile devices is much higher when compared to Shenzhen, this kind of problem is less likely to happen. Hong Kong MTR stations operate under a different frequency, thus they are not affected by any mobile device.