IMU-Aided Dual-Frequency RFID Based Localization in LOS/NLOS Hybrid Environment

2017 ◽  
Author(s):  
Jie Wu ◽  
MingHua Zhu ◽  
Bo Xiao ◽  
Wei He
Keyword(s):  
Indoor Localization ◽  
Measurement Unit ◽  
Line Of Sight ◽  
Dual Frequency ◽  
Site Survey ◽  
Line Of Sight Propagation ◽  
The Mean ◽  
Position Precision ◽  
Rf Signal ◽  
Non Line Of Sight

The mitigation of NLOS (non-line-of-sight) propagation conditions is one of main challenges in wireless signals based indoor localization. When RFID localization technology is applied in applications, RSS fluctuates frequently due to the shade and multipath effect of RF signal, which could result in localization inaccuracy. In particularly, when tags carriers are walking in LOS (line-of-sight) and NLOS hybrid environment, great attenuation of RSS will happen, which would result in great location deviation. The paper proposes an IMU-assisted (Inertial Measurement Unit) RFID based indoor localization in LOS/NLOS hybrid environment. The proposed method includes three improvements over previous RSS based positioning methods: IMU aided RSS filtering, IMU aided LOS/NLOS distinguishing and IMU aided LOS/NLOS environment switching. Also, CRLB (Cramér-Rao Low Bound) is calculated to prove theoretically that indoor positioning accuracy for proposed method in LOS/NLOS mixed environment is higher than position precision of only use RSS information. Simulation and experiments are conducted to show that proposed method can reduce the mean positioning error to around 3 meters without site survey.

scholarly journals Indoor Off-Body Wireless Communication: Static Beamforming versus Space-Time Coding

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Patrick Van Torre ◽  
Maria Lucia Scarpello ◽  
Luigi Vallozzi ◽  
Hendrik Rogier ◽  
Marc Moeneclaey ◽  
...  
Keyword(s):  
Antenna Array ◽  
Base Station ◽  
Space Time ◽  
Error Rates ◽  
Line Of Sight ◽  
Receiver Diversity ◽  
Space Time Coding ◽  
Maximum Ratio Combining ◽  
Line Of Sight Propagation ◽  
Time Coding

The performance of beamforming versus space-time coding using a body-worn textile antenna array is experimentally evaluated for an indoor environment, where a walking rescue worker transmits data in the 2.45 GHz ISM band, relying on a vertical textile four-antenna array integrated into his garment. The two transmission scenarios considered are static beamforming at low-elevation angles and space-time code based transmit diversity. Signals are received by a base station equipped with a horizontal array of four dipole antennas providing spatial receive diversity through maximum-ratio combining. Signal-to-noise ratios, bit error rate characteristics, and signal correlation properties are assessed for both off-body transmission scenarios. Without receiver diversity, the performance of space-time coding is generally better. In case of fourth-order receiver diversity, beamforming is superior in line-of-sight conditions. For non-line-of-sight propagation, the space-time codes perform better as soon as bit error rates are low enough for a reliable data link.

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