Wi-Fi, GPS alternative?

In the concrete canyons of city centres, GPS satellite positioning systems often fail because high buildings block the signals they rely on. But an unlikely back-up for GPS is emerging: Wi-Fi.

A Wi-Fi based positioning system developed in the US and the UK works best where GPS fails: in cities and inside cavernous complexes like shopping malls. And because cheap Wi-Fi technology is already appearing on a raft of gadgets like PDAs, cellphones and laptops faster than more expensive GPS receivers are, the developers predict that Wi-Fi could become central to new location-based applications. They say emergency services in particular could find the system an essential back-up.

At the moment, the new system, called Place Lab, is not as precise as GPS. It can provide accuracy to within 20 to 30 metres, whereas the GPS average is 8 to 10 metres.

click to navigate to a new web page.