Trackio: Tracking First Responders Inside-Out

First responders, a critical lifeline of any society, often find themselves in precarious situations. The ability to track them real-time in unknown indoor environments, would significantly contributes to the success of their mission as well as their safety. In this work, we present the design, implementation and evaluation of TrackIO-a system capable of accurately localizing and tracking mobile responders real-time in large indoor environments. TrackIO leverages the mobile virtual infrastructure offered by unmanned aerial vehicles (UAVs), coupled with the balanced penetration-accuracy tradeoff offered by ultra-wideband (UWB), to accomplish this objective directly from outside, without relying on access to any indoor infrastructure. Towards a practical system, TrackIO incorporates four novel mechanisms in its design that address key challenges to enable tracking responders (i) who are mobile with potentially non-uniform velocities (e.g. during turns), (ii) deep indoors with challenged reachability, (iii) in real-time even for a large network, and (iv) with high accuracy even when impacted by UAV's position error. TrackIO's real-world performance reveals that it can track static nodes with a median accuracy of about 1-1.5m and mobile (even running) nodes with a median accuracy of 2-2.5m in large buildings in real-time.