3G-assisted routing in vehicular networks

Efficient data delivery in vehicular ad hoc networks (VANETs) is particularly challenging due to the unique characteristics of VANETs, such as fast topology change, frequent disruptions and rare contact opportunities. We observe through empirical study that a considerable amount of packets cannot be delivered within time-to-live (TTL). The wide use of third generation (3G) networks inspires us to make the first attempt to exploit the 3G to assist data forwarding in VANETs. In this paper, we explore the problem of packet delivery in VANETs with a budget constraint for 3G traffic. The objective of 3G-assisted packet delivery in VANETs is to maximize delivery ratio while reducing delivery delay. There is an intrinsic tradeoff, however, between delivery ratio and delivery delay when using the 3G. We propose an algorithm for 3G-assisted data delivery. The main idea is to select those packets less probably delivered through the VANET and to spread 3G packets selection decisions over the course of packet delivery. As a result, the cost-free inter-vehicle routing can be exploited as much as possible and the limited 3G traffic can be better utilized. We carry out extensive simulations based on real vehicular GPS traces, and the results demonstrate that our proposed algorithm significantly improve the performance of delivery delivery compared with other algorithms.