Precision of RSS-based indoor geolocation in IoT applications

With the emergence of the Internet-of-Things (IoT), a number of low-power RF devices with diversified power levels will be deployed in the smart buildings. The radiated Received-Signal-Strength (RSS) from these devices can be used to improve the precision of the commonly used RSS-based Wi-Fi localization. In this paper, we introduce an analytical framework for calculation of the Cramer-Rao Lower Bound (CRLB) in an environment with variable radiated powers from sensors to complement the Wi-Fi localization. Since the existing CRLB calculation for the RSS-Based localization uses the differential value of the RSS which eliminates the effect of the transmitted power from the sources, we also introduce the concept of Probability-of-Coverage (PoC), by using which, the transmitted power can be combined with the CRLB and provides more accurate performance evaluation. Experiments and simulations are conducted on the third floor of the Atwater Kent Laboratory at Worcester Polytechnic Institue, where scenarios are designed with deployment of both Wi-Fi and variety of low-power devices. Experimental results show that how different number, power level, and deployment of the low-power devices affect the localization performance and confirm that reasonable precision can be achieved in the dense IoT environment.