6G-Enabled Vehicle-to-Everything Communications: Current Research Trends and Open Challenges

With the developments on Advanced Driver-Assistance Systems (ADAS), autonomous driving and purely unmanned vehicles, such as the Unmanned Aerial Vehicles (UAVs), the pressure on the requirements for Vehicle-to-Everything (V2X) communications has drastically increased during the last few years. However, a new and appealing horizon is open for V2X applications with the advent of the Sixth Generation (6G) of mobile communications. In this paper, we present a review of V2X standards to offer a holistic perspective on the evolution of this technology toward 6G. Then, the key technological enablers for the 6G V2X are identified, namely(a)Non-Terrestrial Networks (NTNs),(b)Ultra Reliable Low Latency Communications (URLLC),(c)Artificial Intelligence (AI),(d)Integrated Sensing And Communications (ISAC) and(e)propagation channel modeling. For each of these technological enablers, the most recent proposals are thoroughly studied and the open challenges and opportunities identified. Our paper intends to serve as a timely roadmap for the development of future 6G V2X networks.