A wireless node location mechanism that employs a differential signal
strength metric to reduce the errors caused by variations in wireless
node transmit power, errors in signal strength detection, and/or
direction-dependent path loss. As opposed to using the absolute signal
strength or power of an RF signal transmitted by a wireless node,
implementations of the location mechanism compare the differences between
signal strength values detected at various pairs of radio receivers to
corresponding differences characterized in a model of the RF environment.
One implementation searches for the locations in the model between each
pair of radio receivers where their signal strength is different by an
observed amount.