By the advantages of small size, low cost and easy deployment, passive Ultra High Frequency Radio Frequency Identification (UHF RFID) technology has become one of the most popular indoor localization technologies. As the most common measurement information, Received Signal Strength Indicator (RSSI) is severely affected by the complex indoor environments, like multipath propagation, Non-Line-of-Sight propagation, noise, etc. It eventually reduces location estimation accuracy. To improve the accuracy of RSSI-based algorithms, pattern matching algorithms are utilized with extra reference tags at fixed and known locations. One of the typical pattern matching algorithms is k-Nearest Neighbor (k-NN) algorithm. There is a problem for pattern matching algorithms utilized into real applications. That is the usually utilized RFID antenna is directional in industries while the algorithms are tested with omnidirectional antennas in experimental tests during research. In this paper, we take k-NN as an example to further analyze the performance difference between these two kinds of antennas. Experimental results show that the localization performance of k-NN algorithms with directional antennas utilized is worse than the results with omnidirectional antennas. But the performance is no significant difference.
['Yang Zhao', 'Zheng Gao', 'Yongtao Ma', 'Kaihua Liu', 'Jianfu Teng']
Localization Performance Analysis for Passive UHF RFID Technology Employing Directional Antennas and Omnidirectional Antennas