Roadcast

Abstract

Content sharing through vehicle-to-vehicle communication can help people find their interested content on the road. In VANETs, due to limited contact duration time and the unreliable wireless connection, a vehicle can only get the useful data when it meets the vehicle which has the exactly matching data. However, the probability of such cases 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 relaxes user's query requirement a little bit so that each user can have more chances to get the requested content quickly. Furthermore, Roadcast ensures popular data is more likely to be shared with other vehicles so that the performance of overall query delay 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 data towards user's query, but significantly different from IR techniques by taking the data popularity factor into consideration. The popularity aware data replacement algorithm ensures that the density of different data is proportional to the square-root of their popularity in the system steady state, which firmly obeys the optimal "square-root" replication rule [6]. Results based on real city map and real traffic model show that Roadcast outperforms other content sharing schemes in VANETs.