An efficient data replication method for data access applications in vehicular ad-hoc networks

Due to the high vehicle mobility, the topology of vehicular ad hoc networks (VANETs) dynamically changes, and disconnections may frequently occur. When two vehicles are disconnected, they are not able to access data from each other. Data replication has been widely used to reduce the effect of intermittent connectivity and improve data access performance in distributed systems. However, many nodes in VANET may only have limited storage space, and thus cannot replicate all the data such as large music files or video clips. To address this problem, we propose an efficient data replication method for data access applications in VANETs. In this method the vehicles are grouped into a platoon and they contribute part of their buffers to replicate data for others in the same platoon and share data with them. When a vehicle leaves the platoon, it prefetches interested data and transfers its buffered data to other vehicles in advance so that they can still access the data after it leaves. We implement this algorithm in NS-2 and GrooveNet Simulators. The GroveNet Simulator is used to generate the vehicle mobility trace file, which is used in the ns-2 simulations. Extensive simulation results show that this method provides high data availability, low data access overhead, and low false alarm rate.