A Lightweight Mobile-Anchor-Based Multi-Target Outdoor Localization Scheme Using LoRa Communication

In recent years, multi-target localization has been identified as an essential technology for delivering on the promise of the Internet of Things (IoT). Multi-target localization has been well-studied and widely deployed in conventional communications systems, but the techniques used in such systems are largely unable to meet the power, cost, and accuracy requirements needed for IoT. In this article, we propose a lightweight Mobile Anchor multi-tarGet IoT loCalization system (MAGIC), which is capable of localizing multiple targets in a low-power and cost efficient manner. MAGIC utilizes a single mobile anchor consisting of a LoRa gateway and a commercial smartphone in order to localize multiple IoT devices embedded with LoRa tags. The anchor moves and communicates with the LoRa tags from multiple locations, greatly reducing the deployment cost compared to a more traditional system with multiple stationary anchors. We formulate the path planning optimization problem of the mobile anchor to minimize the path length while fully accounting for environmental uncertainties. To efficiently solve the optimization problem, we design an online moving strategy that generates the path in real-time as the anchor moves. Through simulation and experimental studies we demonstrate the effectiveness of the proposed scheme both in an empty baseline environment and in a complicated setting around the buildings. Results indicate that our scheme can significantly enhance the localization accuracy and reduce the required path length for the anchor. Compared to the existing outdoor localization systems, the proposed approach shows advantages not only in the localization accuracy but also the overall cost including device cost, spectrum usage and energy consumption.