The idea of having something hover at high altitude over a part of the earth and act as a sort of low-altitude geosynchronous satellite has showed up at various times over the last decade or so. It does in fact solve a large number of the problems associated with wireless access but in order for it to work the aircraft needs to remain nearly stationary for years and needs high bandwidth (and hence high power) links to a ground station. Both these issues are somewhat challenging.

It seems that a Swiss company is sufficiently sure that it has a solution to these challenges that it is willing to launch a prototype next year. As swissinfo reports:

A Swiss of Iranian extraction, Alavi is a former aerospace engineer turned entrepreneur who heads his own firm, Stratxx. Together with a team of 50 scientists, he is preparing a 2007 test run of the airship, which he has named the "X station".

Thanks to a GPS steering system developed by the Swiss Federal Institute of Technology, the 60-meter long helium-filled balloon will remain stationary at 21 kilometres above the earth.

A small-unmanned aircraft outfitted with a mobile phone antenna and other devices for transmitting digital data will be attached to the zeppelin. The X station has been equipped with giant propellers to help counter the almost constant buffeting from the wind.

Solar panels will supply the energy to propel the airplane and antenna. Underneath will be a platform containing technical equipment, conceived by Ruag, the large Swiss aerospace concern.

If this entrepreneur is correct then we could see a significant change in adoption of wireless. This solution would scale far better than most current wireless broadband and broadcast technologies (note that it need not replace the technology, just remove the need for hundreds of base stations) as well as remove the need for many satellites. Personally I would have thought the craft needed to fly closer to 30km above the earth to avoide the jetstream (I recall some NASA tests) but 21km should be safe from the other obvious threat - aircraft.