Signal and array processing techniques for RFID readers

Jing Wang; Moeness Amin; Yimin Zhang

doi:10.1117/12.666712

12 May 2006 Signal and array processing techniques for RFID readers

Jing Wang, Moeness Amin, Yimin Zhang

Proceedings Volume 6248, Wireless Sensing and Processing; 624807 (2006) https://doi.org/10.1117/12.666712
Event: Defense and Security Symposium, 2006, Orlando (Kissimmee), Florida, United States

Abstract

Radio Frequency Identification (RFID) has recently attracted much attention in both the technical and business communities. It has found wide applications in, for example, toll collection, supply-chain management, access control, localization tracking, real-time monitoring, and object identification. Situations may arise where the movement directions of the tagged RFID items through a portal is of interest and must be determined. Doppler estimation may prove complicated or impractical to perform by RFID readers. Several alternative approaches, including the use of an array of sensors with arbitrary geometry, can be applied. In this paper, we consider direction-of-arrival (DOA) estimation techniques for application to near-field narrowband RFID problems. Particularly, we examine the use of a pair of RFID antennas to track moving RFID tagged items through a portal. With two antennas, the near-field DOA estimation problem can be simplified to a far-field problem, yielding a simple way for identifying the direction of the tag movement, where only one parameter, the angle, needs to be considered. In this case, tracking of the moving direction of the tag simply amounts to computing the spatial cross-correlation between the data samples received at the two antennas. It is pointed out that the radiation patterns of the reader and tag antennas, particularly their phase characteristics, have a significant effect on the performance of DOA estimation. Indoor experiments are conducted in the Radar Imaging and RFID Labs at Villanova University for validating the proposed technique for target movement direction estimations.

Citation Download Citation

Jing Wang, Moeness Amin, and Yimin Zhang "Signal and array processing techniques for RFID readers", Proc. SPIE 6248, Wireless Sensing and Processing, 624807 (12 May 2006); https://doi.org/10.1117/12.666712

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