Towards efficient multimedia publish/subscribe in urban VANETs

To facilitate the safe and comfortable driving, vehicular ad hoc networks (VANETs) will be flooded with plenty of multimedia files, such as images, music and video clips. However, due to the dynamic and transient contacts between moving vehicles, these multimedia files distribution over VANETs often involves transmission failure and terrible user experience. In this paper, we propose an efficient infrastructure-less multimedia publish/subscribe scheme for an urban area. In cities, there are lots of parked vehicles, presenting as parking clusters, owning the ability of calculation, storage and communication. Our scheme relies on these parking clusters to cache and distribute the multimedia files for moving users. For each subscription, the parking cluster distributes the file chunks to the subscriber during their contact time. For the remained content chunks, the parking cluster will distribute them to slave vehicles that have no downloading request. Then, the slave vehicles transfer the received file chunks to a parking cluster, where the subscriber can continue the unfinished downloading when it drives through. Theoretical results illustrate the effectiveness of our approach and extensive simulations results demonstrate that the proposed scheme achieves a higher downloading ratio with different file sizes, especially in sparse traffic and multiple subscribers conditions.