Internet of Vehicles Vehicular communication networks have emerged to enable numerous vehicular data services and applications. Conventional vehicular  ad hoc  networks (VANETs) are often operated in the  ad hoc  mode and mainly focus on road safety applications based on the connection between vehicles and roadside units (RSUs). To support vehicular communications, dedicated shortrange communication (DSRC) and cartocar communication consortium (C2CCC) have been initiated in the United States and Europe, respectively. With the new era of the Internet of Things (IoT), the conventional VANETs have evolved to the Internet of Vehicles (IoV). In IoV, each vehicle is envisioned as an intelligent object, equipped with sensing platforms, computing facilities, control units, and storages and is connected to any entity (other vehicles, RSUs, charginggas stations, cloud, and so on) via vehicletoeverything (V2X) communications. Intelligent vehicles can take different roles, i.e., being both a client and a server, taking and providing big data services, leading to numerous new IoV applications, from assistedautonomous driving and platooning, secure information sharing and learning to traffic control and optimization.

Evolutionary V2X Technologies Toward the Internet of Vehicles: Challenges and Opportunities To enable largescale and ubiquitous automotive network access, traditional vehicletoeverything (V2X) technologies are evolving to the Internet of Vehicles (IoV) for increasing demands on emerging advanced vehicular applications, such as intelligent transportation systems (ITS) and autonomous vehicles. In recent years, IoV technologies have been developed and achieved significant progress. However, it is still unclear what is the evolution path and what are the challenges and opportunities brought by IoV. For the aforementioned considerations, this article provides a thorough survey on the historical process and status quo of V2X technologies, as well as demonstration of emerging technology developing directions toward IoV. We first review the early stage when the dedicated shortrange communications (DSRC) was issued as an important initial beginning and compared the cellular V2X with IEEE 802.11 V2X communications in terms of both the pros and cons. In addition, considering the advent of big data and cloudedge regime, we highlight the key technical challenges and pinpoint the opportunities toward the big datadriven IoV and cloudbased IoV, respectively. We believe our comprehensive survey on evolutionary V2X technologies toward IoV can provide beneficial insights and inspirations for both academia and the IoV industry.