Reducing the phase cancellation effect in augmented RFID system

Abstract

This paper proposes to use the spatial diversity of dual-antenna to counter the phase cancellation effect in an augmented radio frequency identification (RFID) system, which is developed for accurate indoor localization. In the augmented RFID system, a tag-like semi-passive RFID component (referred as sensatag) senses the backscattering communication between standard ISO 18000-6C compliant RFID reader and passive tags within its proximity. However, due to the superposition of reader's carrier wave (CW), the amplitude difference in the tag's backscattering signal is significantly attenuated at the sensatag's antenna. We refer to such effect as phase cancellation.To counter the destructive phase cancellation effect, two techniques are proposed based on dual-antenna diversity. In the first one called simple combination technique, simple addition of signals from two antennas is performed; in the second one called receiving path selection technique, signals from both antennas are converted into baseband and then conduct the selection in digital domain. Then we demonstrate the performance of these two techniques in a newly developed Proximity-detection-based augmented RFID system simulator (PASS) framework. The result shows that dual-antenna-based implementations are better than the simple antenna implementation in reducing phase cancellation effect. Moreover, receiving path selection technique reduces the probability of phase cancellation significantly with higher hardware complexity compared with simple combination technique.

Indoor localization using augmented ultra-high-frequency radio frequency identification system for Internet of Things

“…Various techniques have been proposed to counter the phase cancellation by introducing space or modulation diversity. 19,20,30 It is demonstrated that with these techniques, the overall probability of phase cancellation is reduced to be negligible.…”

“…PASS is a time-domain systemlevel simulator, which is based on position-aware RFID system (PARIS) simulation framework. 31 20 Noteworthily, the Q selection algorithm in Gen2 protocol is not implemented in the simulator, since the simulation platform MATLAB is discommodious for scheduling algorithm and also slow for massive computation tasks. Having the whole system implemented in the simulator allows for much faster evaluation of the system and faster validation of the effectiveness of ideas.…”

“…We showed how to use ST in augmented ultra-highfrequency radio frequency identification system (AURIS) for indoor localization in Athalye et al 9 The probabilistic model of detecting a tag by ST is introduced as the function of the distance between the tag to ST. 18 However, through investigation of tag-to-tag backscattering communication link, it is demonstrated that the carrier wave (CW) from RFID reader has a major effect on ST-to-tag detection probability. [19][20][21] In this article, the probabilistic model is extended to be more realistic by integrating the distance and relative angle between the tag and the reader's antenna, and considering the interference of reader's CW on ST, the so-called phase cancellation effect. We propose a novel particle filter with autoregressive model and auxiliary input (PF-AA) as inference algorithm for AURIS indoor localization.…”