1. ABSTRACT…………………………………………………………2
2. INTRODUCTION………………………...…………………………3
3. THEORY…………….………………………………………………6 3.1. LINK BUDGET…………………………………………………6 3.2. NEAR FIELD COUPLING BETWEEN TAGS………………...8 3.3. MODULATION DEPTH………………………………………..9 3.4. SIMULATION…………………………………………………11
4. IMPLEMENTATION………………………………………………12 4.1. SYSTEM…………………………………………………….....12 4.2. READER TAG………………………………………………...13
5. EXPERIMENTS……………………………………………………16 5.1. VERIFYING HFSS SIMULATION OF COUPLED DIPOLE..16 5.2. MEASURING TAG TO TAG DISTANCE…………………...18
6. CONCLUSION……………………………………………………..23
7. REFERENCE………………………………………………………24
CHAPTER 1 ABSTACT
we describe a novel passive RFID system and deal with direct tag-to-tag communication using RFID technology in the presence of external radio frequency field. Tags talk by modulating the external field and thus backscattering the commands to each other. We present the system concept and show its hardware implementation based on TI MSP430 microcontroller. We also provide the theoretical model for modulation depth vs. distance which agrees with experimental results (maximum tag-to-tag communication distance). Finally, we discuss possible applications and outline future work.
CHAPTER 2
INTRODUCTION
Over the past decade, UHF RFID has progressed significantly. Passive UHF RFID tags are emerging in use for many applications, such as tracking apparel and vehicles. The sensitivity for RFID tag ASICs have improved from -8dBm to -18 dBm [1-2] resulting in a three-fold read range improvement. And lastly, ISO 18000-6C (also known as “Gen2”) has been largely adopted as the UHF RFID protocol standard. Despite this progress, transacting with UHF RFID tags still requires a relatively expensive and power hungry RFID reader whose radio contains an active transmitter and a receiver with full-quadrature (IQ) demodulation.
In this paper, we demonstrate
References: [3] “Stochastic communication protocol method and system for RFID tags based on coalition formation, such as for tag-to-tag communication”, US patent application 20080252424, filed Sep. 21, 2006 [4] P [5] J.-S. Park et al., “Extending the Interrogation Range of a Passive UHF RFID System With an External Continuous Wave Transmitter”, IEEE Trans. on Instr. and Measurement, vol. 59, no. 8, 2010, pp. 2191 – 2197 [6] Ettus USRP software radio [Online] [9] A. Sample et al., “Design of an RFID-Based Battery-Free Programmable Sensing Platform”, IEEE Transactions on Instrumentation and Measurement, vol. 57, no. 11, 2008, pp. 2608 – 2615 [10] H.-C [11] M. Todd, W. Burleson, R. Tessier, “The design and assessment of a secure passive RFID sensor system”, IEEE New Circuits and Systems Conference (NEWCAS), 2011 , pp. 494 - 497 [12] M [13] M. Feldhofer at al., ”Semi-passive RFID development platform for implementing and attacking security tags”, International Conference on Internet Technology and Secured Transactions, 2010 , pp. 1 – 6 [14] D [15] U. Muehlmann et al., “Modeling and Performance Characterization of UHF RFID Portal Applications”, IEEE Transactions on Microwave Theory and Techniques, vol. 57, no. 7, July 2009, pp. 1700 – 1706 [16] R RFID Systems: Research Trends and Challenges, chap. 9, Wiley, 2010. [21] P [22] P. V. Nikitin, K. V. S. Rao, and S. Lazar, “An overview of near field UHF RFID”, IEEE RFID conference, 2007, pp. 167-174 [23] A section”, IEEE Antennas and Propagation Society International Symposium, Jul. 1997, vol. 2, pp. 1172 - 1175 [26] L [29] X. Qing, C. K. Goh, Z. N. Chen, “Segmented loop antenna for UHF near-field RFID applications”, Electronics Letters, vol. 45 , no. 17, 2009 [30] L [31] Y. Tanaka et al., ” Change of read range for UHF passive RFID tags in close proximity“, IEEE RFID conference, 2009, pp. 338-345 [32] L [33] H. Yojima et al., “Analysis of read range for UHF passive RFID tags in close proximity with dynamic impedance measurement of tag ICs”, IEEE Radio and Wireless Symposium, 2011 , pp. 110 - 113 [34] G [37] P. V. Nikitin and K. V. S. Rao, “LabVIEW-based UHF RFID tag test and measurement system”, IEEE Transactions on Industrial Electronics, vol. 56, no. 7, pp. 2374-2381, July 2009 [38] Voyantic Tagformance system [Online]