Continuous frequent contact detection over moving objects

With the outbreak of COVID-19 pandemic, contact tracing and social distance monitoring have been increasingly popular due to their capability of avoiding the spread of infectious diseases in communities. For the purpose, many studies investigate the contact events among moving objects (e.g., pedestrians, bicycles). In this light, we define the problem of Frequent Contact Detection (FCD) of moving objects on road networks. The FCD problem aims to find all frequent contact events among moving objects in a time period. We develop a two-phase solution, including contact search and frequent contact event discovery, to answer the FCD problem. For contact search, we develop the Search By Neighbor (SBN) framework and a pre-checking strategy to reduce the computation cost and further improve the efficiency of contact search. For frequent contact event discovery, we use categorized contact event set to find the objects that may form frequent contact events. Extensive experiments conducted on the two real datasets confirm the effectiveness and efficiency of our proposed solutions.