Abstract
In the literature, future vehicle trajectories have been exploited to improve the performance of challenging infrastructure-to-vehicle (I2V) group message delivery over vehicular ad-hoc networks (VANETs). The existing trajectory-based I2V group message delivery protocols typically consist of two phases. Based on the reported vehicle trajectories, phase one identifies an appropriate rendezvous point of the group message and each of the member vehicles. Then, phase two composes a multicast tree to deliver the message to these selected rendezvous points. The message is kept at the rendezvous points for later last-hop delivery when the member vehicles pass through. However, separately handling the rendezvous point selection and the multicast tree construction may significantly restrict the overall message delivery performance. This paper designs a novel trajectorybased I2V groupmessage delivery protocol, i.e., eTGMD, for delaytolerant vehicular applications. eTGMD iteratively selects a promising rendezvous point and extends the currentmulticast tree to cover the selected rendezvous point. Our specific contributions include the following: 1)We prove the trajectory-based I2V group message delivery problem's NP-hardness, 2) we theoretically analyze the worst-case performance bound and time complexity of eTGMD, and 3) we conduct extensive simulation experiments to evaluate eTGMD's message delivery performance.