面向高密度车联网的可靠柔性广播关键技术研究

Reliable broadcasting based on vehicle-to-vehicle communications is the key technique to enable VANET-based driving safety applications. However, realizing reliable broadcasting in VANET settings is very challenging due to three major reasons: 1) the available wireless spectrum is very limited (e.g., FCC in the United States locates only 75MHz bandwidth for DSRC) for the tremendous amount of beacon messages posed by safety-related applications when the node density is high in the network; 2) the network topology is highly dynamic due to the high mobility of vehicles, which makes collision-free media access control very difficult; 3) the quality of the underlying wireless links is very unstable, making reliable broadcasting even more challenging. This project will develop a new set of solutions for reliable broadcasting in VANETs, via three following research thrusts. First, we will investigate flexible broadcasting schemes for safety-related applications, where limited available bandwidth is allocated among vehicles so that the safety utility of the whole network is maximized. Second, we will study distributed media access control schemes in 2D dynamic network topologies. With these schemes, vehicles with different mobility patterns can negotiate with neighboring vehicles and access the media with no collision. Third, we will study network-cost-efficient relay schemes where a sender is aware of the quality of wireless links between itself and its neighbors, and selects the optimal set of neighbors as relay nodes to help forward messages. The goal of these schemes is to guarantee messages successfully received by all neighboring nodes of interest and to minimize the introduced network overhead at the same time. Finally, we will implement a reliable broadcasting prototype and verify the feasibility of all proposed scheme in Shanghai city. The research outcomes will make a significant contribution to the development of VANET-based safety-related applications and will provide the industry with critical knowledge for driving the deployment of intelligent transportation systems.

基于车车通信的可靠消息广播是实现车联网行车安全应用的关键。在高密度车联网环境实现可靠消息广播面临无线带宽缺乏、网络拓扑高度动态、底层无线链路十分不可靠等挑战。针对以上挑战，本课题开展：1）面向行车安全应用的柔性广播技术研究，实现安全效用最大化的拥塞控制；2）针对二维动态拓扑的分布式无冲突媒体访问控制协议研究，实现不同移动特性的自治节点通过分布式协商完成可用无线带宽资源的最优分配和访问；3）链路质量感知的广播转发技术研究，实现在保障广播消息可靠性的同时最小化引入的网络开销。本课题将设计并实现车联网可靠广播原型系统，并在上海城市环境验证各项技术。本课题研究的成功开展将为车联网技术在行车安全应用领域提供关键技术支持，并为推动车联网示范应用和产业化、实现安全交通零事故这一最终目标做出积极的贡献。

基于车车通信的可靠消息广播是实现车联网行车安全应用的关键。在高密度车联网环境实现可靠消息广播面临无线带宽缺乏、网络拓扑高度动态、底层无线链路十分不可靠等挑战。针对以上挑战，本课题开展：1）面向行车安全应用的柔性广播技术研究，提出了安全感知的广播频率适配方案ABC，每辆车会实时估计自己的危险系数同时通过信标交互收集相邻车辆的危险系数，根据每辆车被追尾的风险程度自适应地调整车辆广播频率实现安全效用最大化的拥塞控制；2）针对二维动态拓扑的分布式无冲突媒体访问控制协议研究，设计了一个移动感知的时分MAC协议命名为MoMAC，根据底层道路拓扑结构和道路上的车道分布来动态分配时槽以控制信道访问，实现不同移动特性的自治节点通过分布式协商完成可用无线带宽资源的最优分配和访问；3）链路质量感知的广播转发技术研究，分析了大量真实数据集来刻画城市环境下车辆通信特征，设计了一种链路质量感知的可靠广播机制即CoBe，实现在保障广播消息可靠性的同时最小化引入的网络开销。此外，本课题还开展了多项移动感知技术研究，包括基于自适应压缩感知的邻近节点分布估计方法PeerProbe、基于稀疏GPS数据的危险驾驶行为识别方法APP、基于短基线双目摄像头的测距方法HyperSight、基于短基线双麦克风的音源定位技术研究HyperEar、保护移动感知数据隐私的盲回归建模及更新方法、智能终端安全语音交互方法SeVI、基于连续相互验证的移动设备在线防丢检测方法CoSafe、无需相机外参的单目3D目标检测框架MonoEF、在线时序点云语义分割框架TempNet。本课题设计并实现了车联网可靠广播原型系统，并在上海城市环境验证了各项技术。本课题研究的成功开展将为车联网技术在行车安全应用领域提供关键技术支持，并为推动车联网示范应用和产业化、降低安全交通事故这一最终目标做出积极的贡献。