Way back in September 1998, we reported on a plan to provide cities with blanket wireless data coverage using base-stations mounted on cheap aeroplane rather than expensive satellites.

The company behind the scheme, St. Louis, Missouri-based Angel Technologies, calls the system Halo, and has been quietly developing the system ever since the test flights it made in late 1998. So far it has yet to roll the service out commercially, though the company has managed to break a few world records for high-altitude flight.

Now it has a rival. Atlanta, Georgia-based Sanswire Networks will next month launch a base-station suspended beneath an 75m unmanned airship which will float around 20km (13 miles) up in the air, kept in place by ground-control and a GPS fix. Angel's Halo planes will fly at around 16km (10 miles).

Again, the idea is to provide users with a variety of mobile data services. Like Angel, Sanswire is pitching the scheme as a way of providing not only a cheaper service than satellite-based alternatives can offer, but one that yields a stronger signal, enabling smaller, lower power end-user equipment.

Of course, mast-mounted transmitters are better still on that score, but Angel and Sanswire can offer a much wider coverage from one aircraft than one tower can. They can also reach areas where it may be uneconomical to install masts, whether for geographical reasons, local objections or citing regulations.

Sanswire claims its 'stratellite' blimps will provide a coverage area of up to 300,000 square miles, as does Angel. Both companies are also alike in being unwilling to say when they will be able to offer commercial wireless services. To be fair, it could be some way off, and since many similarly grandiose ventures have missed targets and plans, they're probably right to be circumspect for now.

Having missed its original January 2004 launch target, UK broadband-by-balloon operation SkyLinc is also keen to keep whatever targets it now has private for the time being. ®

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