TriLoc: Toward Accurate Indoor Localization With Assistance of Microwave Reflections

With the development of the Internet of Things (IoT), indoor localization technology plays a vital role in smart factories, smart cities, and other fields. When using the network infrastructures such as Wi-Fi, some conventional localization technologies usually need multiple access points (APs), which involve time and data synchronizations. As a result, those drawbacks hinder the deployment of those localization technologies. In this article, we propose TriLoc, a single AP-based indoor localization system with the assistance of microwave reflections, which has the minimum overheads compared to the existing schemes. The insight is that the reflection paths and the direct path experience the same phase errors, and thus, it can be used for locating the user device using only a single AP. In the system, we first estimate the angle of arrivals (AoA) and time of flight (ToF) of propagation paths and then use the multipath triangle that consists of one first-order reflection path and the direct path to locate the user device. Finally, we construct the prototype using software-defined radio and evaluate it in various indoor environments. The experimental results show that TriLoc can achieve submeter localization accuracy using only a single AP.