The A to Z of wireless

U is for Underground

While mobile network coverage does not currently extend to Tube tunnels, Transport for London (TfL) has previously mooted plans to bring connectivity to stations and trains, issuing a tender for the Waterloo & City line back in 2007.

However TfL told silicon.com earlier this year that the company has yet to receive a "credible proposal" for pushing out mobile coverage to the line, adding that "the unique nature and environment of the Tube mean that project costs would be prohibitively high at this time".

However, in an unexpected twist, the government's comms minister Lord Carter championed the cause of Underground mobiles in his Digital Britain report - flagging up the Tube as a coverage blackspot and calling for it to be plugged in time for the 2012 Olympics.

The report adds that the government is willing to address any regulatory or "similar constraints" that might be acting as a barrier to an Underground deployment. However there's still no cash on the table so an imminent Tube rollout does not seem any more likely.

While commuters may not yet have wireless comms on the Tube, London's emergency services are already able to speak to each other when on the London Underground. Earlier this year the Airwave emergency services comms system was rolled out to the whole of the Underground network meaning police and other emergency services personnel don't have to send staff above ground to radio for help.

The project saved cash by piggybacking on the existing Connect digital trunk system, used for communication by TfL workers, rather than building an entirely new infrastructure.

Passengers on Glasgow's subway are also getting mobile connectivity underground. Wireless network vendor Arqiva is in the process of hooking up the city's 15 subway stations via a distributed antenna system that could also be used to roll out wi-fi connectivity at stations in future.