iLoc: A Low-Cost Low-Power Outdoor Localization System for Internet of Things

Node location information is very important to many novel applications of Internet of Things (IoT). Typically, IoT nodes are resource-constrained, and thus costly and energy-hungry localization techniques fall short. In this paper, we present iLoc, a low-cost, low-power and wide-area localization system for IoT applications. iLoc is built on the emerging LoRa technology and overcomes the disadvantage of many short-range localization techniques. Central to iLoc is a mobile anchor node comprising of a simplified LoRa gateway and a smartphone. To locate an IoT node, the anchor node moves around, during which the LoRa gateway receives its locations from the smartphone, and communicates with the IoT node for the information of time of flight (ToF) as well as received signal strength indication (RSSI). In order to obtain a better distance estimation, both RSSI and ToF are integrated in the regression analysis of distance between the anchor node and the IoT node. We further design an iterative localization algorithm by judiciously deciding the locations of the anchor node step by step. The LoRa gateway and tag we prototype cost less than 10 and 5 dollars, respectively. We conduct extensive experiments and the results demonstrate that iLoc achieves an average localization error of 1.33m and power consumption of 0.25mAh in an open environment.