Abstract: A localization method and system, including determining phases of a plurality of response signals at a plurality of frequencies received from a radio frequency identification (RFID) tag in response to interrogation signals by a reader at the plurality of frequencies; calculating a first distance estimate of a distance between the RFID tag and the reader based on a signal strength measured from a first response signal of the plurality of response signals; based on the phases and the first distance estimate, calculating a phase slope; and determining a second distance estimate of the distance based upon the phase slope.

Abstract: A localization method and system, including determining at least two phases associated with at least two response signals transmitted by a radio frequency identification (RFID) tag at different frequencies in response to a plurality of interrogation signals transmitted by a reader; determining a first distance estimate of a distance between the RFID tag and the reader based on a signal strength measured from a first response signal of the at least two response signals; based upon the first distance estimate, generating a set of phase data points that follows a substantially periodic function over a range of frequencies; and determining a second distance estimate of the distance based upon the at least two phases and the periodic function.

Abstract: A localization method and system, including calculating a first distance estimate of a distance between a radio frequency identification (RFID) tag and a reader based on information associated with at least one of a plurality of response signals received from the RFID tag in response to interrogation signals by the reader at a plurality frequencies, measuring a signal strength of each of the received plurality of response signals to create a received signal strength indicator (RSSI) signature, predicting an error in the first distance estimate using the RSSI signature, and determining a final distance estimate of the distance by modifying the first distance estimate based on the predicted error.