Enabling Efficient WiFi-Based Vehicular Content Distribution

For better road safety and driving experience, content distribution for vehicle users through roadside Access Points (APs) becomes an important and promising complement to 3G and other cellular networks. In this paper, we introduce Cooperative Content Distribution System for Vehicles (CCDSV) which operates upon a network of infrastructure APs to collaboratively distribute contents to moving vehicles. CCDSV solves several important issues in a practical system, like the robustness to mobility prediction errors, limited resources of APs and the shared content distribution. Our system organizes the cooperative APs into a novel structure, namely, the contact map which is based on the vehicular contact patterns observed by APs. To fully utilize the wireless bandwidth provided by APs, we propose a representative-based prefetching mechanism, in which a set of representative APs are carefully selected and then share their prefetched data with others. The selection process explicitly takes into account the AP's storage capacity, storage status, inter-APs bandwidth and traffic loads on the backhaul links. We apply network coding in CCDSV to augment the distribution of shared contents. The selection of shared contents to be prefetched on an AP is based on the storage status of neighboring APs in the contact map in order to increase the information utility of each prefetched data piece. Through extensive simulations, CCDSV proves its effectiveness in vehicular content distribution under various scenarios.