New technique for indoor location based on RSSI method using UHF RFID systems

A new method for indoor location by RFID systems in the UHF band (frequency band from 902 MHz to 928 MHz) based on a conventional location technique is presented in this communication. A practical study on the signals involved and measured as well as the variable parameters of the reader-tag link has been performed to identify a location method considering both regulatory and pragmatic criteria. The proposed technique is based on measuring the reflected power from the target as in the RSSI (Received Signal Strength Indicator) method. The main originality of this approach consists in eliminating the effect due to the tag´s variable behavior, introducing an adaptive scale factor in the trilateration procedure. Areas for improvement are also considered: a dedicated architecture, multi-frequency aspects and adding a fourth reader. Simulation results are presented to validate the proposed approaches, show the robustness of solutions and quantify the obtained performances.