[hamner]

I imagine there would be some overhead (e.g. each user transmitting a certain user-specific pattern every 1/2 second, and each AP transmitting a certain AP-specific pattern every 1/2 second), to calibrate the location of each user in AP-space. Fundamentally I think all the calculations involved would be fast linear algebra operations that could be done in hardware on the order of microseconds.

[NathanKP]

This brings to mind a very interesting idea as well. If the changing physical location of the receiver is causing changes in the composite wireless signal the device is receiving, and the base stations are recalculating and refreshing this all the time very quickly it could potentially be a very reliable and accurate GPS as well.

[jerf]

Actually, I don't think so. This isn't finding your physical location, then computing the correct profile for that location; it empirically probes the performance your location is experiencing, then directly uses that performance information. While you could analyze the results and at least take a stab at the physical location, it's quite possible it will work no better than cell tower triangulation.

Even trying to empirically map certain performance profiles to certain spaces may be impractical if the client radios and antennae performances differ enough to throw off the profiles, which if I understand this properly and given our proclivities for making things as cheap as possible, probably means this won't work either.