Vehicular Ad-hoc Networks (VANETs) have been widely recognized as one of the most promising technologies to deliver data between vehicles to support various vehicular applications. In environments of VANETs with the feature of frequent network dynamics due to high mobility of vehicles, geographic routing is considered as an attractive approach because it can send data to a destination vehicle by using only the location information of vehicles. However, mobility of destination vehicles brings about a very challenging issue for data delivery to them because they have frequent location changes due to their continuous movements. Fortunately, the trajectory and road map information provided by on-board navigation systems of vehicles can efficiently support data delivery to them. Thus, we propose an efficient data delivery protocol that uses the trajectory information of a destination vehicle on a road map in VANETs. The proposed protocol first decides an efficient reception point on the trajectory of the destination vehicle by providing an arithmetical model based on a road map information to achieve the cost-minimized data delivery. Next, to deliver data to the efficient reception point, the proposed protocol determines an efficient data route by considering both the moving direction of the destination vehicle and the forwarding direction of data. Last, the proposed protocol provides a trajectory-based forwarding and a redirection forwarding based on data caching to cope with trajectory changes of the destination vehicle due to its moving speed and direction changes, respectively. Simulation results conducted in various environments verify that the proposed protocol achieves more efficient data delivery performances than the existing protocols.

车载自组织网络（VANET）已被广泛认为是在车辆之间传送数据以支持各种车载应用的最有希望的技术之一。在由于车辆的高机动性而具有频繁的网络动态特性的VANET环境中，地理路由被认为是一种有吸引力的方法，因为它可以仅通过使用车辆的位置信息将数据发送到目标车辆。然而，目的地车辆的机动性给它们的数据传送带来了非常具有挑战性的问题，因为目的地车辆由于其连续运动而频繁地改变位置。幸运的是，由车辆的车载导航系统提供的轨迹和道路地图信息可以有效地支持向它们的数据传递。从而，我们提出了一种有效的数据传输协议，该协议在VANET的路线图上使用目标车辆的轨迹信息。所提出的协议首先通过提供基于道路地图信息的算术模型来实现目标车辆轨迹上的有效接收点，以实现成本最小的数据传递。接下来，为了将数据传递到有效接收点，提出的协议通过同时考虑目标车辆的移动方向和数据的转发方向来确定有效的数据路径。最后，所提出的协议提供了基于轨迹的转发和基于数据缓存的重定向转发，以分别应付目标车辆由于其移动速度和方向变化而引起的轨迹变化。