Distributing location-dependent data in VANETs by guiding data traffic to high vehicle density areas

It is useful to share location-dependent data items generated by vehicles such as a picture image of a traffic accident and the traffic condition around an intersection in vehicular ad hoc networks (VANETs) for improving the driver safety and comfort. In VANETs, due to the mobility of vehicles, it is difficult to reliably access data on other nodes. To improve the accessibility of data from a vehicle to a vehicle, it will be effective to distribute replicas of location-dependent data in a certain areas such as the area around the birthplace of the data item so that a request message geocasted to a location of interest can reache a vehicle that has the replica of the requested data item. In this paper, we propose an information-sharing scheme for location-dependent data items generated by vehicles using the push and pull approaches to balance the reliable message delivery and the traffic for the data dissemination called “assigning populated area as message storage area (APAM) scheme”. In the APAM scheme, request messages for location-dependent data are sent from each vehicle to locations along routes where there are many vehicles. Additionally, replicas of the data items are distributed around the birthplace and on the main streets where the vehicle density is high. These operations enable the request messages to encounter the vehicles that have the replica of the corresponding data item on the main streets. Simulation results showed that the proposed scheme improved the access success rate compared with the existing strategies that distribute replicas to vehicles near the birthplace of the original data items.