The concept of indoor GPS has huge potential, but it also requires overcoming some fairly serious stumbling blocks too. But progress is being made, and Nokia is right up front, leading the way. We explain more after the break.

Indoor GPS doesn't seem like a difficult concept in theory, but the very nature of GPS makes it extremely tricky to get right. Think about it: in-car GPS devices often have problems in heavily built-up areas, because of all the buildings and walls in the way. So imagine yourself inside those buildings, or behind these walls and the nature of the challenge becomes clear. It's a problem Nokia has been working to solve for years, though. Back in 2008 it showed off a prototype indoor GPS system that claimed to be able to determine your position to within 1m.

It achieved this using triangulation, the same technique used by the aGPS systems in mobile phones, which calculate your location based on your distance from two or more phone masts. In the case of indoor GPS, however, your location is triangulated using Wi-Fi points.

But this comes with its own difficulties, as unlike with mobile phone masts, the radio waves are seldom able to travel in a straight line between the wireless point to your phone, so it's difficult to gauge actual distances. In Nokia's demo, for instance, the 1m accuracy was only achieved using specialised add-on beacons and tracking tags. And it's that idea that's at the heart of Nokia's newly announcedNokia High Accuracy Indoor Positioning system. I

t uses a network of strategically placed beacons around a building to create an indoor map, and can narrow down your position to within just 30cm using localised triangulation. The potential for such systems is huge. In a shopping complex, for instance, you could deliver localised special offers from shops as you walk past them, or you could give pin-point directions to your seat in a big stadium. The possibilities are nearly endless, and as the Nokia High Accuracy Indoor Positioning system shows, Nokia is shining the light for others to follow.