Intercontact time between moving vehicles is one of the key metrics in vehicular ad hoc networks (VANETs) and central toforwarding algorithms and the end-to-end delay. Due to prohibitive costs, little work has conducted experimental study on intercontacttime in urban vehicular environments. In this paper, we carry out an extensive experiment involving thousands of operational taxies inShanghai city. Studying the taxi trace data on the frequency and duration of transfer opportunities between taxies, we observe that thetail distribution of the intercontact time, that is, the time gap separating two contacts of the same pair of taxies, exhibits an exponentialdecay, over a large range of timescale. This observation is in sharp contrast to recent empirical data studies based on human mobility,in which the distribution of the intercontact time obeys a power law. By analyzing a simplified mobility model that captures the effect ofhot areas in the city, we rigorously prove that common traffic influxes, where large volume of traffic converges, play a major role ingenerating the exponential tail of the intercontact time. Our results thus provide fundamental guidelines on design of new vehicularmobility models in urban scenarios, new data forwarding protocols and their performance analysis.

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