V2I communications complement V2V safety applications by dealing with emergency situations such as crash scenarios that the V2V program cannot handle or that could be addressed more effectively. However, depending on the deployed infrastructure, we can distinguish between three situations regarding allowed communications: infrastructure-based, infrastructure-less and intermittent infrastructure. We will focus in vehicular networks with an intermittent connectivity, where the unavailability of direct communication with RSUs poses huge problems, especially when vehicles have to send safety-related messages to the infrastructure. In fact, a scattered vehicular infrastructure leads to non-homogeneous coverage, especially in highway scenarios extending over long distances; it is very expensive to set up an infrastructure across the whole road. Our objective is to address the challenges related to safety information forwarding towards the RSU in such networks by enabling vehicles to make an optimal forwarding decision based on contextual information relative to the infrastructure and the neighbourhood. In this work, we present HyRSIC (Hybrid Routing for Safety data with Intermittent V2I Connectivity), a routing approach, combining geographical and topological routing, proposed to deal with data forwarding in intermittent infrastructure-based networks. We conducted an in-depth evaluation from three different perspectives: scalability, reliability and efficiency. The results show that HyRSIC is able to scale quickly and adapt promptly to density and speed variations. Compared to GPSR and its variant ILTS+GPSR, HyRSIC offers the best packet delivery ratio for sparse networks, 12-27% higher, and the lowest End-to-End delivery delay, 25-50% less.

V2I 通信通过处理紧急情况来补充 V2V 安全应用程序，例如 V2V 程序无法处理或可以更有效地解决的崩溃情况。然而，根据部署的基础设施，我们可以区分三种关于允许通信的情况：基于基础设施、无基础设施和间歇性基础设施。我们将专注于具有间歇性连接的车辆网络，其中无法与 RSU 直接通信会带来巨大的问题，尤其是当车辆必须向基础设施发送与安全相关的消息时。事实上，分散的车辆基础设施会导致覆盖不均匀，尤其是在长距离延伸的高速公路场景中；在整条道路上建立基础设施非常昂贵。我们的目标是通过使车辆能够根据与基础设施和社区相关的上下文信息做出最佳转发决策，从而解决与此类网络中向 RSU 转发安全信息相关的挑战。在这项工作中，我们提出了 HyRSIC（具有间歇性 V2I 连接的安全数据混合路由），一种结合地理和拓扑路由的路由方法，用于处理基于间歇性基础设施的网络中的数据转发。我们从三个不同的角度进行了深入的评估：可扩展性、可靠性和效率。结果表明，HyRSIC 能够快速扩展并迅速适应密度和速度变化。与 GPSR 及其变体 ILTS+GPSR 相比，HyRSIC 为稀疏网络提供了最佳的数据包传输率，高出 12-27%，