2-Way Localization of RFID Tags

Identification and localization of hospital equipment (op instruments) or blood bags improves cost-efficiency, safety and provides easy, direct access when needed. The system presented here combines different types of localization in addition to identification with RFID. It is based on passive UHF RFID tags that provide information about distance and angle by means of phase estimation (FD-PDOA and SD-PDOA). This 2-way localization is enhanced by an estimation of the motion within the room via TD-PDOA. This paper presents the discrete hardware setup, the measurement concept and a demonstrator. It shows a maximum measurement tolerance of 0.5 m in distance and 6° in angle estimation, as well as an accuracy of up to 89 % in distance difference under calibrated conditions.