# 5G Cross-Border Operation for Connected and Automated Mobility: Challenges and Solutions
## 1 Introduction  
Both the telecom and the automotive industries are going through profound transformations [1]. The development of emerging 5G technologies is a clear exemplification of this new revolutionary trend [2]. The telecom industry is moving beyond voice and mobile broadband, the two core services that have powered the industry until today. The two novel opportunities for future telecom services focus on the \"massive\" connection of machine-type objects as well as on \"ultra-reliable and low-latency\" connectivity services. This new service provision entails a transition from a \"horizontal\" service delivery model, where services have been defined independently from their consumers, towards a \"vertical\" delivery model, where the services provided are tailored to specific needs of industry sectors and verticals. 5G is regarded as the key technology that will empower this transition [3]. In its turn, the automotive industry is evolving towards a vision where cars are becoming more and more automated and wirelessly connected to cooperate with each other for safer and more efficient driving. Today, the majority of safety and efficiency features in vehicles are supported by the on-board sensors, which are limited to visual line-of-sight. Connectivity offers a good complement to the on-board sensors by extending vision and detection ranges even when visual line-of-sight is not available. In addition, connectivity is key to cooperative functions. Both would be required to achieve higher automated driving (AD) levels. Moreover, the business models for the automotive industry are drastically changing in the coming years and the real revolution is about to arrive. For the success of such a revolution, it is necessary that both the telecom and the automotive industry cooperate to shape the future by addressing all the challenges that connected, cooperative and automated mobility (CCAM) poses for the innovation arena. Europe is playing a pivotal role in this revolution. As dictated in its 5G strategic action plan [4], 5G aims at becoming a reality by the end of this decade, ensuring large-scale commercialization by the end of his decade at the latest. One of the objectives of this action plan is to promote pan-European multi-stake holder trials to act as catalysts to turn technological innovation into business potentials. This becomes particularly interesting, and indeed necessary, when it comes to testing 5G technologies for CCAM, especially when cross-border operation needs to be guaranteed. CCAM can offer a variety of services that can have a profound impact into economy and society. It will lead to higher road safety and thus fewer fatalities or serious injuries, more traffic efficiency and less environmental pollution. New business opportunities can evolve in areas such as logistics, thus enabling economic growth and sustainability of well-being. Among others, the possibility to enable automated transportation paths along highways crossing a continent is of high interest. However, ensuring that vehicle-to-everything (V2X) services, i.e., those enabled by communication between vehicles to anything (X), can operate along different countries, when crossing borders, is challenging. When operating in cross-border settings, services based on V2X communications have some unique properties, which pose a challenge and specific new requirements in the design and deployment of the information and communications technology (ICT) infrastructure. A first unique property is that many V2X applications have a limited area of interest. Information is often only needed close to the source where it was generated; for example, an alert of a traffic jam or accident may be needed to be informed only to the other vehicles close to the location of the event. For a typical mobile radio network offering services like voice and data communication, it does not matter that peering points between mobile network operators (MNOs), vehicular clouds, and public data networks are located far from the \"edge\".