# 5G Beyond 3 GPP Release 15 for Connected Automated Mobility in Cross-Border Contexts
## 1 Introduction  
Automation Levels 4 and 5 (L4 and L5), defined by Society of Automotive Engineers (SAE), will not require someone to take over driving. Such automation levels are expected to be first introduced in highways, as the technical complexity on those roads is lower and the investment profitability prospects are higher compared with urban roads. Cross-border corridors are particularly interesting, as they fit in the highway road type, and they constitute an essential backbone for road transport between countries. However, achieving seamless connectivity that satisfies the needs of connected and automated mobility (CAM) is very challenging in cross-border contexts. The main challenges include roaming and handover latencies, uninterrupted access to required communications and computing resources, data interoperability and accurate geo-positioning. The vehicle-to-everything (V2X) communication systems can integrate different communication technologies, including cellular systems in centimetre wave (cm-wave) and millimetre wave (mmWave), dedicated short range spectrum (DSRC) and vehicular visible light communications (VVLC). Currently, the automotive industry is putting its effort into cellular systems and DSRC implementations [1]. The 3 rd Generation Partnership Project (3 GPP) defined the first set of cellular standards for V2X communication under the name long-term evolution (LTE)-V2X in 3 GPP Release 14 (Rel-14). LTE-V2X is evolving to 5G, providing the main radio interface to support cellular V2X communication [2]. On the other hand, DSRC vehicular communication technology uses Wi-Fi based physical layer (PHY) and medium access control (MAC) layer protocols following the IEEE802.11p standard. The adaptation of the widely-used IEEE 802.11 standard for Wi-Fi is being implemented in Europe under the name ITS-G5. As a readily-available, internationally-recognised standard which does not require licensed spectrum, it seems that DSRC technology is well placed. Moreover, some experimental works have already demonstrated its suitability for some specific autonomous driving operations [3]. However, it has a shorter range (few 100 metres), lower data rate, worse spectrum efficiency and more limited quality of service (QoS) management capabilities than 5G [4]. Regardless of the adoption of 5G for CAM, its deployment for consumer electronics is going to be done in any case, fostering new business opportunities for many actors at different levels and sectors [5; 6; 7], including small and medium-sized enterprises (SMEs) working on data exploitation at cloud level, which is another big incentive for adopting 5G in CAM instead or in combination with DSRC. There are already some works studying the features to be added and the potential of 6G [8; 9]; however, the application of 5G technology in different verticals is still in the experimental stage and needs more research. In 2017, the European Union agreed to establish 5G cross-border corridors with the ambition of having the biggest experimental area in 5G technology. The European Commission, coordinated with public and private actors, is currently focused on these corridors to run CAM projects and to devise digital policies and regulations. Stemming from the work done in one of these ongoing projects, 5G-MOBIX [10], the present article aims to shed some light on the roadmap for deploying SAE L4 and L5 CAM in cross-border roads employing 5G technologies.