Advances in low-power wireless communications and microelectronics make a great impact on a transportation system and pervasive deployment of roadside units (RSUs) is promising to provide drive-thru Internet to vehicular users anytime and anywhere. Downloading data packets from the RSU, however, is not always reliable because of high mobility of vehicles and high contention among vehicular users. Using intervehicle communication, cooperative downloading can maximize the amount of data packets downloaded per user request. In this paper, we focus on effective data downloading for real-time applications (e.g., video streaming and online game) where each user request is prioritized by the delivery deadline. We propose a cooperative downloading algorithm, namely, max-throughput and min-delay cooperative downloading (MMCD), which minimizes an average delivery delay of each user request while maximizing the amount of data packets downloaded from the RSU. The performance of MMCD is evaluated by extensive simulations and results demonstrate that our algorithm can reduce mean delivery delay while gaining downloading throughput as high as that of a state-of-the-art method although vehicles highly compete for access to the RSU in a conventional highway scenario.

PDF