Techniques for determining a position of a mobile device are provided. An example of these techniques is a method that includes performing a passive scan for wireless transceivers proximate to the mobile device to generate passive scan results, generating a first wireless transceiver list, comprising a first set of wireless transceivers, transmitting a request to at least one wireless transceiver from the first wireless transceiver list requesting that the at least one wireless transceiver perform a scan, generating a second wireless transceiver list comprising identifying information for a second set of wireless transceivers, proximate to the at least one wireless transceiver, measuring signals received from wireless transceivers selected from at least one of the first wireless transceiver list and the second wireless transceiver list, and determining the position of the mobile device based at least in part on the signals measured.