Less is More: Efficient RFID-Based 3D Localization

Radio-Frequency Identification (RFID) technology has successfully proven its potential for locating objects in a 3-dimensional (3D) space. Current RFID-based 3D localization is built on the ethos of striving for accuracy. This paper takes the first step toward efficient localization with high time efficiency and energy efficiency, which are important for accelerating positioning operation and prolonging system lifetime. To this end, we propose leveraging known locations of deployed reference readers and reference tags to probe as a few reference tags as sufficient for localization. Counter-intuitively, localization using fewer reference tags promises rather higher efficiency yet without necessarily sacrificing accuracy. We design efficient passive scheme and efficient active scheme for both typical RFID-based 3D localization scenarios, locating a target tag using reference readers/tags and locating a target reader using reference tags. We evaluate their performance through quantitative analysis and extensive simulation. The results show that the proposed schemes outperform existing schemes in time efficiency and energy efficiency by over 95% on average.