In this paper, we present a demodulation structure suitable for a reader receiver in a passive Radio Frequency IDentification (RFID) environment. In a passive RFID configuration, undesirable DC-offset phenomenon may appear in the baseband of the reader receiver. As a result, this DC-offset phenomenon can severely degrade the performance of the extraction of valid information from a received signal in the reader receiver. To mitigate the DC-offset phenomenon, we propose a demodulation structure to reconstruct a corrupted signal with the DC-offset phenomenon, by extracting useful transition information from the corrupted signal. It is shown that the proposed method can successfully detect valid data from a received signal, even when the received baseband signal is distorted with the DC-offset phenomenon.
1. Finkenzeller, K., RFID Handbook — Fundamentals and Applications in Contactless Smart Cards and Identification, John Wiley & Sons Ltd, 2003.
2. Dobkin, D. M., The RF in RFID, Elsevier Inc., 2008.
3., "EPC radio-frequency identity protocols Class-1 Generation-2 UHF RFID protocol for communications at 860MHz ∼ 960MHz version 1.1.0,", EPCglobal, 2007.
4., "Radio-frequency identification for item management — Part 6: Parameters for air interface communications at 860 MHz to 960 MHz ,", ISO/IEC 18000-6C, 2007.
5. Fan, Z. G., S. Qiao, J. T. Huangfu, and L. X. Ran, "Signal descriptions and formulations for long range UHF RFID readers," Progress In Electromagnetics Research, PIER 71, 109-127, 2007.
6. Kim, D. Y., J. G. Yook, H. G. Yoon, and B. J. Jang, "Interference analysis of UHF RFID systems," Progress In Electromagnetics Research B, Vol. 4, 115-126, 2008. doi:10.2528/PIERB08010607
7. Shi, X. L., X. W. Shi, Q. L. Huang, and F. Wei, "An enhanced binary anti-collision algorithm of backtracking in RFID system," Progress In Electromagnetics Research B, Vol. 4, 263-271, 2008. doi:10.2528/PIERB08012304
8. Loo, C. H., et al., "Chip impedance matching for UHF RFID tag antenna design," Progress In Electromagnetics Research, PIER 81, 359-370, 2008.
9. Proakis, J. G., M. Salehi, and G. Bauch, Contemporary Communication Systems Using MATALB & Simulink, 2nd Ed., Thomson-Brooks/Cole, 2004.
10. Haykin, S., Communication Systems, 4th Ed., John Wiley & Sons, Inc., 2001.
11. Tan, A. and C. E. Saavedra, "A binary phase shift keying demodulator using pulse detection," IEEE International Conference on Electrical and Electronics Engineering, 2004.