OwLL: Accurate LoRa Localization using the TV Whitespaces

LoRa is a popular Low-Power Wide-Area Networking (LPWAN) technology that allows devices powered by a ten year AA battery to connect to radio infrastructure miles away. One of the most promising features of LoRa is the ability to track the location of radios from a distance, enabling applications ranging from inventory tracking, smart infrastructure monitoring and structural health sensing. Yet, state-of-the-art LoRa localization systems experience errors of several tens or even hundreds of meters in location tracking, owing to the narrow bandwidth and limited battery life of LoRa devices. This paper presents OwLL, a LoRa localization system that limits location error to few meters with commodity LoRa clients in a wide-area network. Our key innovation is the development of a distributed base station network made of individually low-cost components that together span a wide bandwidth that encompasses the TV whitespaces and offers high aperture, crucial to localization accuracy. We demonstrate how this network can aggregate signal measurements made across multiple different narrowband channels of a LoRa client to triangulate it at fine accuracy. We implement and evaluate OwLL on a testbed spanning a large university campus centered in a major U.S. city and demonstrate a 9 m (across line-of-sight and non-line-of-sight) median error in localization.