Wi-Fi and RFID Convergence

We're seeing another trend emerge - the convergence of active RFID
and Wi-Fi.Active RFID involves tags with an energy source (batteries)
that emit a signal to readers some distance away.It's provides almost
precise location of tags by coordinates within a particular physical
space,but designed for use inside or in neighboring open spaces,such as
parking lots or courtyards.

http://flying-rugs.com/wi-fi-and-rfid/