Communication device and a method for localization

An RFID reader comprising a radio frequency (RF) module and a baseband (BB) module, wherein the RF module is configured to:

• measure a phase of a signal received from an RFID tag, the signal having a first frequency;
• measure a phase of at least one other signal received from the RFID tag;
• the at least one other signal having a second frequency;
• and
• wherein the BB module is configured to:
• determine a phase pattern of a measured phase versus frequency based on the measured phase of the signal and the measured phase of the at least one other signal including identifying a relationship between the measured phase and frequency by applying extrapolation to estimate phase values for missing frequencies of a series of measure phase versus frequency values before determining a phase difference between consecutive values of a series of measured phase versus frequency values to estimate a fitting curve of the series of measured phase versus frequency values;
• pattern matching the phase pattern with a reference phase pattern of a plurality of pre-determined reference phase patterns, wherein the reference phase pattern is associated with a distance between RFID tag and RFID reader;
• and
• determine the distance between RFID tag and RFID reader based on the pattern matching.

A method for localizing a device, the method performed in a communication device, the method comprising:

• measuring a phase of a first signal received by the communication device from the device, the first signal having a first frequency;
• measuring a phase of a second signal received by the communication device from the device;
• the second signal having a second frequency;
• determining a phase pattern of the measured phase of the first signal and the measured phase of the second signal versus frequency;
• measuring a phase of a first reference signal received by the communication device from at least one reference device of a known location or distance from the communication device, the first reference signal having a first frequency;
• measuring a phase of a second reference signal received by the communication device from the at least one reference device;
• the second reference signal having a second frequency;
• determining a reference phase pattern of the measured phase of the first reference signal and the measured phase of the second reference signal versus frequency including identifying a relationship between the measured phase and frequency by applying extrapolation to estimate phase values for missing frequencies of a series of measure phase versus frequency values before determining a phase difference between consecutive values of a series of measured phase versus frequency values to estimate a fitting curve of the series of measured phase versus frequency values;
• and
• pattern matching the phase pattern with the reference phase pattern, and determining the distance between the communication device and the device or the location of the device based on the pattern matching.