Effects of Various Factors on RSSI from Positioning Point of View with Wearables

Abstract

Continuous improvement and availability of low-cost commercial off-the-shelf (COTS) sensors with low form factor and low power consumption have recently increased the use of wearable applications dramatically. For most of the cases, spatiotemporal data is crucial for the information acquired by a wearable device, to be meaningful. Received signal strength (RSS) fingerprints based indoor positioning methods have gained intense focus due to their advantages over the other methods. However, RSS-based indoor localization methods are prone to lower accuracies due to the disturbance caused by various factors that affect the signal link quality. Proper knowledge and well understanding of RSS behaviors with different factors can assist in achieving higher accuracy in position estimation. Nevertheless, most of the existing studies overlooked this important aspect. This study demonstrates the effects of several parameters like antenna polarization, sensor placement height, device diversity and presence of the human body on signal RSS value from positioning point of view with wearables. Experiments are conducted using IEEE 802.15.4 based 2.4 GHz radio modules. Analysis of collected data shows that the considered parameters have significant impacts on RSSI that should be taken into account to improve positioning accuracy.