A new perspective on the impact of diffraction in proximity of micro-metals for indoor geolocation

The indoor localization has received considerable attention in the field of positioning. It has been reported that time-of-arrival (ToA) based localization performs superior in comparison to the received-signal-strength (RSS) and the angle-of-arrival (AoA) based techniques in line-of-sight (LOS) condition. However, the accuracy of such systems is limited mainly due to unexpected large ranging errors observed in indoor environment, which are primarily caused by obstruction of the direct path and the effect of diffraction of the radio waves around the edges of micro-metallic objects. It is known that the analysis of effects of the micro-metallic objects on the accuracy of the range estimates could be indeed a challenging problem. In this paper, we investigate both simulation and analytical approaches based on applicability of electromagnetic (EM) methods to analyze the effects of micro-metallic objects on the accuracy of the range estimates. According to the first approach, the results of MATLAB based 2D finite-difference-time-domain (FDTD) simulation are compared to the 500 MHz bandwidth channel profiles obtained from a real-time frequency-domain measurement to analyze the accuracy of 2D simulation. Subsequently, we compare the achieved results of our analytical calculations to that of 3GHz channel profile measurements. Our studies reveal the fact that the presented simulation and analytical results are in close agreement with the results attained from the measurement campaign.