FM radio for indoor localization with spontaneous recalibration

Abstract

The position of mobile users has become highly important information in pervasive computing environments. Indoor localization systems based on WiFi signal strength fingerprinting techniques are widely used in office buildings with an existing WiFi infrastructure. Our previous work has proposed a solution based on exploitation of a FM signal to deal with environments not covered with WiFi signal or environments with only a single WiFi access point. However, a general problem of indoor wireless positioning systems pertains to signal degradation due to the environmental factors affecting signal propagation. Therefore, in order to maintain a desirable level of localization accuracy, it becomes necessary to perform periodic calibrations of the system, which is either time consuming or requires dedicated equipment and expert knowledge. In this paper, we present a comparison of FM versus WiFi positioning systems and a combination of both systems, exploiting their strengths for indoors positioning. We also address the problem of recalibration by introducing a novel concept of spontaneous recalibration and demonstrate it using the FM localization system. Finally, the results related to device orientation and localization accuracy are discussed. © 2010 Elsevier B.V. All rights reserved.