Location of wireless nodes using signal strength weighting metric

A method for estimating the location of a wireless node relative to a plurality of radio receivers operative to detect the strength of RF signals, wherein a RF coverage map, corresponding to each of the radio receivers, characterizes the signal strength values for locations in a physical region, comprising

• collecting signal strength values, detected at a plurality of radio receivers, corresponding to signals transmitted by a wireless node;
• and
• computing the estimated location of the wireless node by comparing, for all unique pairs of radio receivers, the differences in the signal strength values detected by the plurality of radio receivers to corresponding differences in the signal strength values in the RF coverage maps associated with the plurality of radio receivers, wherein the comparison is weighted as a function of at least one of the signal strength values detected by each unique pair of radio receivers, and wherein the computing step comprises
• computing, for all unique pairs of radio receivers, the sum of the squares of the difference between the signal strength values detected by a pair of radio receivers less the difference between the signal strength values in the RF coverage mans associated with the pair of radio receivers;
• weighting each of the computed sums based on the lower of the two signal strength values detected by the corresponding pair of radio receivers;
• combining the weighted sums to create a differential error surface;
• and
• finding the minimum of the differential error surface.

A wireless node location mechanism operating in association with a wireless network environment comprising a plurality of radio receivers operative to detect the signal strength of signals transmitted by wireless nodes, wherein a RF coverage map, corresponding to each of the radio receivers, includes signal strength values for locations in a physical region, comprising:

• a wireless node location module operative to
• receive, from at least some of the plurality of radio receivers, the detected signal strength of RF signals transmitted by a wireless node;
• and
• compute the estimated location of the wireless node by comparing, for all unique pairs of radio receivers, the differences in the signal strength values detected by the plurality of radio receivers to corresponding differences in the signal strength values in the RF coverage maps associated with the plurality of radio receivers, wherein the comparison is weighted as a function of at least one of the signal strength values detected by each unique pair of radio receivers, and wherein the compute step comprises
• compute, for all unique pairs of radio receivers, the sum of the squares of the difference between the signal strength values detected by a pair of radio receivers less the difference between the signal strength values in the RF coverage maps associated with the pair of radio receivers;
• weight each of the computed sums based on the lower of the two signal strength values detected by the corresponding pair of radio receivers;
• combine the weighted sums to create a differential error surface;
• and
• find the minimum of the differential error surface.