With the exponential growth in technologies for the vehicular Internet of things applications and high demands for autonomous road vehicles, future transportation systems are projected to be revolutionized on a global scale. This new landscape requires a stable, flexible, and business-friendly base of connectivity, networking, and computing technology, in which Unmanned Aerial Vehicles (UAVs) can play an important role. A UAV-enabled Intelligent Transportation System (ITS) can provide a cost-effective communication solution to improve the safety and efficiency of the transportation system, particularly if the data traffic is nonhomogeneous and nonstationary. Typically, wireless is the communication medium between vehicles and UAVs in an ITS setting, which is based on the IEEE802.11p MAC protocol adopted by car manufactures. However, the IEEE 802.11p MAC protocol is modified solely for omnidirectional antennas, which restricts network coverage, delay, and throughput. In comparison, the directional antenna has greater network coverage, spatial reuse, and bandwidth. In addition, a multiaccess edge computing (MEC) facility at the backhaul link will provide ultralow latency and high bandwidth services to meet the increasingly growing demand for latency-sensitive vehicle applications such as vehicular video data analytics, autonomous driving, and intelligent navigation. Therefore, this article aims to propose a novel dual-mode MAC protocol that can work in two antenna modes, i.e., directional and omnidirectional. For modeling and simulation purposes, we use the Optimized Network Engineering Tool (OPNET) and aim to seek an evaluation with respect to throughput, media access delay, and retransmission attempts. The results obtained demonstrate the effectiveness of the proposed scheme.

中文翻译：

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支持无人机的智能运输系统的双模式媒体访问控制机制

随着车载物联网应用技术的指数级增长以及对自动驾驶道路车辆的高要求，预计未来的交通运输系统将在全球范围内发生革命性的变化。这种新形势要求连接，网络和计算技术具有稳定，灵活和对业务友好的基础，其中无人机可以在其中发挥重要作用。启用了无人机的智能运输系统（ITS）可以提供一种具有成本效益的通信解决方案，以提高运输系统的安全性和效率，尤其是在数据流量不均匀且不稳定的情况下。通常，无线是ITS设置中车辆与UAV之间的通信介质，它基于汽车制造商采用的IEEE802.11p MAC协议。但是，IEEE 802。11p MAC协议仅针对全向天线进行了修改，这限制了网络覆盖范围，延迟和吞吐量。相比之下，定向天线具有更大的网络覆盖范围，空间重用性和带宽。此外，回程链路上的多访问边缘计算（MEC）设施将提供超低延迟和高带宽服务，以满足对延迟敏感的车辆应用（如车载视频数据分析，自动驾驶和智能导航）日益增长的需求。因此，本文旨在提出一种新颖的双模式MAC协议，该协议可以在两种天线模式下工作，即定向和全向。为了进行建模和仿真，我们使用优化的网络工程工具（OPNET），旨在寻求有关吞吐量，媒体访问延迟，和重传尝试。获得的结果证明了该方案的有效性。