Abstract
This work studies the three-dimensional (3D) identification performance of UHF RFID systems with commodity hardware. Detailed three-dimensional propagation modeling is developed, with ray-tracing that allows examination of tagas well as reader-antenna diversity. It is shown that multipath can enhance identification performance compared to free-space conditions. Furthermore, it is found that tag diversity can enhance identification performance on the order of 10%. Reader-antenna diversity becomes beneficial only when special attention is given to controlling the destructive summation of the transmitted fields and simple, general antenna-installation rules are provided. Performance can be further enhanced with the introduction of a phase shifter or appropriate transmission scheduling, and various examples are discussed. Measurements inside a room with a dense three-dimensional grid of passive RFID tags confirmed the results. Finally, a method to perform power-measurements with commodity RFID hardware that exploits the sensitivity-during-read threshold of each tag is put forth.
Original language | English |
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Pages (from-to) | 175-194 |
Number of pages | 20 |
Journal | IEEE Antennas and Propagation Magazine |
Volume | 53 |
Issue number | 1 |
Publication status | Published - Feb 2011 |
Keywords
- Electromagnetic measurements
- Multipath channels
- Radiofrequency identification
- Ray tracing
- RFID tags
- UHF propagation