Abstract: Vehicular Ad-hoc networks (VANETs) are promising information-sharing technologies for modern intelligent transportation systems (ITS)，in which information can be disseminated and shared among a group of moving vehicles through wireless communication devices. Previous data dissemination schemes for VANETs arc unable to meet the rectuirements of effective and efficient data dissemination in VANETs due to the dynamic nature of the framework such as the intermittent connection between vehicles. An Adaptive Copy and Spread (ACS) data dissemination algorithm was proposed for opportunistic VANETs to adaptively adjust the dissemination strategics. Through making use of the moving parameters of vehicles (e. g. dircction,vclocity)，ACS can dynamically calculate the number of message copies to be broadcasted so that vehicles can intelligently start or stop a message spread stage. In addition, ACS was designed to keep the message located at the effective area's boundary, inform the entering vehicles as soon as possible. Our simulation resups show that ACS outperforms traditional Random Choice (RC) algorithm and Epidemic spreading (ED) algorithm with less network resource consumption in broad scenarios.

Key words: Vehicular Ad-hoc networks, Opportunistic networks, Data dissemination, Epidemic sprcading