Leveraging Power of Transmission for Range-Free Localization of Tiny Sensors

Modern environmental monitoring systems are being envisioned as constellations of tiny smart sensors, densely deployed on the territory to be monitored. Data provided by such sensors is meaningless if it is not equipped with information about the context to which it refers. Such a context is mainly related to the location of sensors, which allows to manage collected data by means of Geographic Information Systems. Due to scarce resources of tiny sensors characteristics, localization services are usually range-free and based on simple measurements provided by the majority of radio chips, such as the Received Signal Strength Indicator (RSSI). However, existing solutions suffer of inaccuracy issues, due to the unreliability of the adopted indicators. This article proposes a range-free localization algorithm based on data fusion, which combines the RSSI with the Power of Transmission (PoT), by estimating the RSSI at different PoT levels. We show, through experimentation on real tiny devices, how this simple solution allows reducing the localization error to about 16% with respect to state-of-art algorithms.