Joint RSS and Ranging Fingerprint for LoRa Indoor Localization

In recent years, several of the latest communication technologies enable Round Trip Time (RTT) for positioning in addition to Received Signal Strength (RSS). It is expected to improve consistency of the observable locations. This approach has been gaining support from several companies such as Google, which introduced this feature in the Android system. As a result, RTT estimation is now available in several recent off-the-shelf devices, opening a wide range of new approaches for estimating location. RTT is most of the time associated with trilateration solutions. However, few works exist assessing the feasibility and accuracy of RTT as an input for fingerprinting based positioning. In this paper, we try to contribute to fill this gap by investigating the performance of ranging fingerprint indoor LoRa based localization solution in terms of accuracy and positioning errors compared to RSS. The ranging is estimated from RTT measurements. Results reveal RTT or ranging is an excellent input for fingerprinting solutions and its fusion with RSS achieve a very good accuracy in both Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) scenarios.