Researchers at Kingston University near London have invented a Wi-Fi system that lets emergency teams communicate with one another using smartphones and tablet computers when conventional radio channels have stopped working.

Today's emergency response teams typically depend on conventional Terrestrial Trunked Radio (TETRA) systems working on reserved frequencies but these come with some painful limitations, starting with limited bandwidth for data, expensive handsets and incompatibility between the systems used in different countries.

In crisis situations such as earthquakes or terrorist events such as the London tube bombings of 2005, experience shows that radio systems can also quickly overload in a given location, making it difficult for members of an emergency team to communicate with one another or with HQ.

The alternative system developed by the Kingston University team headed by Dr Christos Politis uses a combination of Wi-Fi connections between smartphones and tablet computers (Apple and Android) and a special application running on each device to create an ad-hoc peer-to-peer network of up to 10 devices supporting voice and video as well as data.

Critically, only one of the devices has to have Internet connectivity for the whole group to reach back to a command centre through that 'super-node'.

The advantages are numerous. Even without an Internet connection, teams can still reach one another without the need for a network to support that channel. It can also lower costs by supporting ruggedized versions of the devices already sold in the high street.

"In the future the technology will also be able to act as sensors and pick up humidity levels, workers' heart rates, temperatures, movement and pass these on to a central operator," said Politis.

Funded with a grant from the EU's PEACE Project, the team and Kingston University are currently in the process of patenting the technology behind the system with a view to licensed commercialisation. Because of the patenting issues, Politis is reluctant to explain the design of the peering protocols or how it securely juggles the client devices in difficult circumstances not to mention third-party applications such as video.

After a successful road test earlier this year in Portugal, the technology is undergoing further testing of its stability as the number of devices scales beyond 10.

Longer term, Politis believes the technology has applications beyond emergency teams, including any form of peer network built atop ad-hoc Wi-Fi, including possibly social networking.

"This could be one of the enablers of the future 'Internet of things,'" said Politis.