Towards Privacy-Preserving Wi-Fi Monitoring for Road Traffic Analysis

The penetration of Wi-Fi enabled personal mobile internet devices has dramatically increased over the last few years. Consequentially, the presence of those devices within driving vehicles has also skyrocketed recently. The majority of these devices periodically emit short Wi-Fi frames in order to speed up the scanning process for available networks when changing location. We investigate the feasibility to use these transmissions for road traffic analysis. After having conducted two real-world measurement campaigns we can conclude that the number of probe requests emitted on Austrian motorways today is sufficiently high in order to re-identify in-vehicle-devices traveling between two locations. This allows to detect changes of the current traffic condition between observation points. The results we show indicate that by proper post-processing of measurement data, meaningful travel time information for the respective highway segment can be derived.