Patent ID: 7433696

Claim:
A method for estimating a location of a wireless node relative to a plurality of radio receivers operative to detect the strength of RF signals, comprising collecting signal strength values, detected at the plurality of radio receivers, corresponding to signals transmitted by a wireless node wherein RF coverage maps, associated with corresponding ones of the radio receivers, each comprise an origin location, and a coverage map region defined by a matrix having elements containing signal strength values for corresponding locations in a physical region out to a threshold signal strength level; selecting at least two of the coverage maps of the radio receivers that detected signals transmitted by the wireless node; defining a search region by determining, based on the origin locations and coverage map regions of the selected coverage maps, an intersection of the RF coverage maps; and computing, within the defined search region, the estimated location of the wireless node based on the collected signal strength values and the selected RF coverage maps corresponding to the plurality of radio receivers, wherein the computing step comprises computing, for each radio receiver, an individual error surface based on the RF coverage map associated with the radio receiver and the signal strength detected by the radio receiver; aggregating the individual error surfaces to create a total error surface; and assessing, within the search region, the total error at each location in the total error surface.