# 5G-V2X Communications and Networking for Connected and Autonomous Vehicles
###### Abstract  
In the last decade, there has been a surge in interest in connected and automated vehicles (CAVs) and related enabling technologies in the fields of communication, automation, computing, sensing, and positioning. Indeed, CAVs are expected to revolutionize future transportation and quality of life. By leveraging novel efficient air interfaces, a combination of different radio access technologies, and disruptive network softwarization techniques and edge/cloud computing solutions, fifth generation (5G) positions itself to guarantee the ultra-low latency, the ultra-high reliability, and the high-data-rate vehicle-to-everything (V2X) connectivity demanded by CAV applications. The complexity and uniqueness of the vehicular ecosystem, the variety of involved stakeholders and standards-developing organizations, the evolving nature of envisioned CAV applications, and the numerous activities engaging the research community in 5G-enabled V2X are among the main motivations of this Special Issue aimed at collecting the most recent achievements in this vibrant field. The papers included in this Special Issue of the _Future Internet_ journal provide a comprehensive overview of the emerging topics in the field of 5G V2X communications and networking. In more detail, they cover aspects ranging from the Third Generation Partnership Project (3 GPP) 5G and V2X architectural enhancements to physical layer coding techniques and radio access technologies, while considering issues associated with network orchestration and localization. Some of them also report achievements from recently concluded and ongoing collaborative research projects. Moreover, the collected papers are heterogeneous in nature, which is one of the main strengths of the Special Issue: they range from technically sound theoretical analysis and timely architectural design contributions to algorithmic design and practical contributions. In particular, a total of six excellent original research papers, with authors from both industry and academia, have been accepted that address many of the aforementioned challenges, following a rigorous review process involving expert reviewers in the respective areas. The first paper [1] dissects the main challenges associated with cross-border and multi-operator V2X deployment focusing on three representative Cooperative, Connected, and Automated Mobility (CCAM) services: Tele-Operated Driving, High-Definition map generation and distribution for autonomous vehicles, and Anticipated Cooperative Collision Avoidance. Enhancements of roaming schemes, inter-edge-cloud coordination mechanisms, network slice selection, and Quality of Service(QoS) prediction are presented as solutions conceived within 5 GCroCo, which is a Horizon 2020 EU project in which 5G technologies will be trialed for CCAM in cross-border scenarios. The achievements of a further Horizon 2020 project, 5G Communication Automotive Research and innovation (5 GCAR), are reported in the second paper [2]. The authors present the enhancements--e.g., in terms of network orchestration and management, edge computing, and multi-connectivity cooperation--conceived by 5 GCAR for the 5G system level architecture proposed by the 3 GPP to support V2X use cases. By focusing on the 3 GPP architecture for V2X communications, the third paper [3] focuses on the networking aspects and describes the potential for leveraging Information-Centric Networking, and Named Data Networking (NDN) in particular, for data exchange in V2X contexts. The goal of the paper is to analyze the specific design aspects and enhancements in the 3 GPP V2X architecture to enable NDN-based data exchange and relevant features (e.g., in-network caching and the aggregation of named requests) and to assess the achieved improvements over traditional host-centric IP networking.