The trials successfully transmitted data from sky to Earth

Airships in the stratosphere beaming back broadband capable of speeds up to 120Mbps may seem like fantasy.

But tests in Sweden have suggested it could become a reality within three to five years.

A successful trial of the technology has been conducted by researchers, led by the University of York in the UK.

Trials using a 12,000 cubic metre balloon, flying at an altitude of around 24 kilometres for nine hours, have proved it can successfully operate a data rate link of 11Mbps.

"Proving the ability to operate a high data rate link from a moving stratospheric balloon is a critical step in moving towards the longer term aim of providing data rates of 120Mbps," said Dr David Grace, the project's principal scientific officer.

Broadband on the move

The Capanina research consortium consists of 14 worldwide partners, including BT's research wing, and is partly funded by the European Union.

The radio link equipment was developed by the University of York

Broadband via telephone lines has speed limitations while satellite is expensive and can support only a limited number of users.

Balloons hovering in the stratosphere could become an attractive alternative as consumers demand ever higher bandwidth, said Alan Gobbi, the marketing manager of the York Electronic Centre.

The centre is the commercial unit of the University of York and the body charged with co-ordinating the project.

"One business model could be an alternative to wired access in suburban areas where costs of roll out are high. It could be offered on high-speed trains and in remote areas," he told the BBC News website.

Stacked up against satellite the cost is likely to be attractive, he said.

"The launch cost of the infrastructure is likely to be one-tenth that of satellite and one airship can support a user density one thousands times that of satellite," he said.

During the trials, the researchers managed to send data via wi-fi at at distances ranging up to 60 kilometres.

Trials of the technology will continue in Japan next year.