SIMO UHF RFID Reader Using Sensor Fusion for Tag Localization in a Selected Environment

This paper presents an ultra high frequency (UHF) radio frequency identification (RFID) reader for transponder (tag) localization in a selected environment—an AVL engine test bed. The choice of the UHF RFID reader hardware components is based on the evaluation of radio channel measurements in the engine test bed. The presented method of the channel measurement based implementation of an RFID reader can be favorably applied to realize reliable custom-built UHF RFID systems in any selected environment. The core of the implemented UHF RFID reader is a software defined radio (SDR) that enables rapid prototyping and thus a fast verification of localization techniques. The localization is realized by a single input multiple output (SIMO) antenna configuration and the exploitation of phase difference of arrival (PDoA) techniques. The implemented PDoA techniques allow to estimate the direction and the range of a tag. A sensor fusion of direction and range estimates enables a two dimensional tag localization. The functionality of the reader hardware implementation and the implemented PDoA techniques have been verified in an anechoic chamber reaching a localization accuracy of 15 cm.