Roadcast: A Popularity Aware Content Sharing Scheme in VANETs

Content sharing through vehicle-to-vehicle communication can help people find their interested content on the road. In VANETs, due to limited contact duration and unreliable wireless connection, a vehicle can get the useful data only when it meets another vehicle and the encountered vehicle has the exactly matched data. However, the probability of such case is very low. To improve the performance of content sharing in intermittently connected VANETs, we propose a novel P2P content sharing scheme called Roadcast. Roadcast ensures popular data is more likely to be shared with other vehicles so that the overall query delay and the query hit ratio can be improved. Roadcast consists of two components called popularity aware content retrieval and popularity aware data replacement. The popularity aware content retrieval scheme makes use of Information Retrieval (IR) techniques to find the most relevant and popular data towards user's query. The popularity aware data replacement algorithm ensures that the density of different data is proportional to their popularity in the system steady state, which firmly obeys the optimal "square-root" replication rule. Results based on real city map and real traffic model show that Roadcast outperforms other content sharing schemes in VANETs.