基于车载通信实时交通信息的城市道路路径选择方法

为车辆出行规划最优路径是智能交通系统（ITS）的一个重要研究目标.本文根据有效的实时交通信息提出一种车辆路径选择机制，这种机制包括两个阶段.第一阶段，由有线或无线传输设备和车载通信设备组成的交通信息系统（TIS），收集用于车辆出行导航的实时交通信息数据，并将其存储至交通信息中心.第二阶段，利用有效的实时交通信息，提出两种基于Dijkstra 的路径选择算法，即一步路径选择和逐步路径选择.前者在整个车辆出行过程中，仅在其出行开始阶段单次计算通往目的地的最优路径.逐步路径选择在每个交叉口都实时更新并计算通往目的地的最优路径，并提出使用两种新优化方法以避免算法形成环路.利用NCTUns 6.0 进行路网仿真，结果表明两种算法都借助于实时交通信息，且逐步路径选择优于一步路径选择.

Transportation Routing in Urban Environments Using Updated Traffic Information Provided through Vehicular Communications

Finding optimal routes for vehicles to reach their destinations is deemed to be a significant challenge and that is an objective in Intelligent Transportation Systems (ITS). In this paper, we propose a mechanism for vehicle routing based on the availability of updated traffic information. The proposed mechanism includes two phases. In the first phase, we propose a TIS (Traffic Information System) which collects the updated traffic status and stores it in the traffic information center. The proposed TIS approach consists of wired or wireless infrastructure and ad hoc inter-vehicle communications. This information will be used for vehicle navigation when a vehicle intends to run some errands. In the second phase, through exercising the available updated traffic information; we propose two different Dijkstra- based vehicle route suggestion algorithms named one-step vehicle path suggestion and step-by-step vehicle path suggestion. In the former, the algorithm is invoked only once at the beginning of the trip in order to obtain the best route towards the destination. The obtained route is then used by the vehicle throughout the journey. Nevertheless, in step-by-step path suggestion algorithm the suggested route toward the destination is being updated and refreshed at each intersection. The proposed step- by- step algorithm is further enhanced by two novel methods for avoiding loop creation. Results of the extensive simulation study using NCTUns 6.0 network simulator shows that both of the routing algorithms use the updated traffic information while the step-by-step algorithm outperforms the one-step path suggestion algorithm.