WiFiTrace: Network-based Contact Tracing for Infectious Diseases Using Passive WiFi Sensing.

Contact tracing is a well-established and effective approach for containment of spread of infectious diseases. While bluetooth-based contact tracing method using phones have become popular recently, these approaches suffer from the need for a critical mass of adoption in order to be effective. In this paper, we present WifiTrace, a network-centric approach for contact tracing that relies on passive WiFi sensing with no client-side involvement. Our approach exploits WiFi network logs gathered by enterprise networks for performance and security monitoring and utilizes it for reconstructing device trajectories for contact tracing. Our approach is specifically designed to enhance the efficacy of traditional methods, rather than to supplant it with a new technology. We design an efficient graph algorithm to scale our approach to large networks with tens of thousands of users. We have implemented a full prototype of our system and deployed it on two large university campuses. We validate our approach and demonstrate its efficacy using case studies and detailed experiments using real-world WiFi datasets.