A method and apparatus are provided for estimating the location of a portable device. The method includes the steps of providing a plurality of location anchor transceivers and a plurality of enhanced location anchor transceivers within a region, each of the plurality of location anchor transceivers and enhanced location anchor transceivers operating from respective predetermined locations, a portable
transceiver within the region detecting and measuring a
signal parameter of a
signal from at least some of the plurality of location anchor transceivers and enhanced location anchor transceivers within the region, a location engine determining a location of the portable
transceiver based upon the
signal measurements of the portable
transceiver and the respective predetermined locations of the plurality of location anchor transceivers and enhanced location anchor transceivers within the region, each of the plurality of enhanced location anchor transceivers detecting and measuring a
signal parameter of a signal from at least some of the plurality of location anchor transceivers and other enhanced location anchor transceivers, the location engine receiving the measured signal parameters from each of the plurality of enhanced location anchor transceivers, the location engine calculating an estimated location for each of the plurality of enhanced location anchor transceivers from the measured signal parameters and the location engine calculating a location error for each of the plurality of enhanced location anchor transceivers based upon the estimated location and predetermined location of the enhanced location anchor transceiver.