Analysis of Effects of Micro-Metal on Ranging Error Using Finite Difference Time Domain Methods

The concept of indoor localization has attracted considerable attention in the field of positioning. It has been reported that time-of-arrival based localization techniques perform superior compared to received signal strength techniques or angle-of-arrival techniques. However, the accuracy of such systems is limited mainly due to unexpected large ranging errors observed in indoor environment which are mainly caused by obstruction of the direct path by a metallic object. The analysis of effects of the micro-metallic objects on the accuracy of the range estimates are shown to be a very challenging problem. In this paper we discuss some full-wave EM methods to analyze the effects of micro-metallic objects on the accuracy of the range estimates. The results of electromagnetic simulation via FDTD are compared to the channel profiles obtained from a real-time frequency-domain measurement to analyze the accuracy of a 2D approximation used. The measurements were conducted with the bandwidth of 500 MHz centered around 1 GHz. The FDTD simulation was carried out using our MATLAB FDTD Suite.