Radio resource management for vehicular communication via cellular device to device links: review and challenges The vehicletoeverything (V2X) communications, as enabled by cellular devicetodevice (D2D) links, has recently gained greater attention owing to the remarkable capacity it displays in enhancing traffic safety, effectiveness, and comfort. It is in this context that the present paper can be set, whereby a new technology is advanced, relating to the fifth generation (5G) associated D2D based vehicular communication, as lately approved by the 3GPP standardization community. In effect, V2X communication appears to raise a number of critical issues that are closely interrelated, mainly, those attached to stringent latency and reliability requirements. In this respect, an exhaustive investigation of the state of the art is put forward D2D based vehicular communication is detailed, throughout the scope of the present work. In the first place, a thorough examination of the D2D associated works, treating such a study area from different perspectives, is displayed. In a second place, the major reason lying behind the application of the D2D communication for vehicular service purposes, involving the possibilities it provides, along with the expected prospective potentials, it could offer, are investigated. In addition, a special emphasis is laid on the particular restrictions associated with the implementation of the V2X Radio Resource Management problem formulation. In a last step, and on reviewing a number of papers dealing with the area of D2D based vehicular communication, some disciplines that do not see to have been satisfactorily and exhaustively elaborated are depicted, while highlighting potential work associated challenges, mainly concerning the D2D effective integration for vehicular communication purposes.

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.