Inertial measurement unit–aided dual-frequency radio frequency identification localization in line-of-sight and non-line-of-sight hybrid environment

Jie Wu,Bo Xiao,Minghua Zhu,Wei He

doi:10.1177/1550147718762033

Abstract

The mitigation of non-line-of-sight propagation conditions is one of main challenges in wireless signal–based indoor localization. When radio frequency identification localization technology is applied in applications, the received signal strength fluctuates frequently due to the shade and multipath effect of radio frequency signal, which could result in localization inaccuracy. In particular, when tag carriers are walking in line-of-sight and non-line-of-sight hybrid environment, great attenuation of received signal strength will happen, which would result in great positioning deviation. The article puts forward a dual-frequency radio frequency identification–based indoor localization approach in line-of-sight–non-line-of-sight hybrid environment with the help of inertial measurement unit. Dual-frequency radio frequency identification includes passive radio frequency identification and active radio frequency identification. Passive radio frequency identification is used to assist in determining the tag initial location with passive reader. Active radio frequency identification is used to locate the tag and send the sensor information to active radio frequency identification readers. The proposed method includes three improvements over previous received signal strength–based positioning methods: inertial measurement unit–aided received signal strength filtering, inertial measurement unit–aided line-of-sight/non-line-of-sight distinguishing, and inertial measurement unit–aided line-of-sight/non-line-of-sight environment switching. Also, Cramér–Rao low bound is calculated to prove theoretically that indoor positioning accuracy for the proposed method in line-of-sight and non-line-of-sight mixed environment is higher than position precision using only received signal strength information. Experiments are conducted to show that the proposed method can reduce the mean positioning error to around 3 m without site survey.

Highlights

The radio frequency identification (RFID) technology has attracted considerable attentions over the past decades due to its advantages of non-touch, low cost, high accuracy, and long-distance communication
This article puts forward an inertial measurement unit (IMU)–aided indoor positioning method in LOS and NLOS mixed environment based on dualfrequency RFID technology
The simulation about the proposed method is performed in section ‘‘Cramer–Rao low bound (CRLB) calculation,’’ and the experiments are conducted in section ‘‘Experiment.’’ Conclusions and discussion are made in the final section

Summary

Introduction

The radio frequency identification (RFID) technology has attracted considerable attentions over the past decades due to its advantages of non-touch, low cost, high accuracy, and long-distance communication. The second solution is the fingerprint-based indoor localization method.[5,6,7,8] Before the location measurement, the location of tags and the corresponding RSS are recorded as the fingerprint of the environment. The environment is so complex which includes both LOS and NLOS signal propagation that it is difficult to establish an accurate model to work on this problem.[9,10,11,12] A lot of articles proposed different kinds of method. This article puts forward an inertial measurement unit (IMU)–aided indoor positioning method in LOS and NLOS mixed environment based on dualfrequency RFID technology. In addition to filtering the Gauss noise for RSS, the RSS fluctuation caused by NLOS environment is mitigated with the help of IMU in this article. The simulation about the proposed method is performed in section ‘‘CRLB calculation,’’ and the experiments are conducted in section ‘‘Experiment.’’ Conclusions and discussion are made in the final section

Related work

Materials and methods

Findings

Discussions and conclusion