Prefetching-based content download for highway vehicular ad hoc networks

The development of wireless communication technology enables high-speed vehicles to download data from road-side units (RSUs). However, due to the high mobility of vehicles and the dark areas resulting from sparse deployment of RSUs, the amount of data that can be downloaded by individual vehicle is quite limited. To tackle this problem, in this paper, we exploit the combination of both prefetching and carry-and-forward scheme to facilitate data download of individual vehicle in dark areas. When a tagged vehicle requests to download data, it first informs multiple selected RSUs to prefetch the data, then we select reverse vehicles to form into linear clusters to cooperatively download the prefetched data from the selected RSUs. When the tagged vehicle leaves the coverage of a RSU, it will continue to download data from cooperative clusters encountered in dark area, which indirectly extends the access time from the tagged vehicle to RSUs, and accordingly facilitates the data download process significantly. Based on the proposed cooperative communication scheme, the process of data download and achievable throughput are derived and analysed theoretically. Finally, we conduct extensive simulations to verify the performance of the proposed strategy. The results show the significant benefits of the proposed scheme in terms of increasing data download volume and throughput.