# 5G Beyond 3 GPP Release 15 for Connected Automated Mobility in Cross-Border Contexts
## 3 Challenging Cross-Border Use Cases  
### Identification of Use Cases  
As noted in the introduction, cross-border contexts create challenging situations for CAM, specially regarding service continuity. In order to plan the infrastructure and technology required for operating 5G-enabled CAM in cross-border roads it is necessary to conduct some experiments. It is a common approach in engineering to define a set of use cases that represent the most significant interactions with the system under test. 3 GPP identified a set of V2X scenarios grouped into five categories [32]: advanced driving, vehicle platooning, extended sensors, remote driving and vehicle QoS support. Vehicle platooning aims at green driving by grouping a set of vehicles to travel together one after the other. The vehicles that are part of the platoon exchange periodic data to move in a cooperative way. Here, autonomous vehicles can automatically join and leave platoons. Autonomous platooning is expected to be adopted first by trucks, which are some of the main users of cross-border corridors. Platooning optimises transport by using roads more effectively, reducing traffic jams and consequently delivering goods faster. \"Extended sensors\" is focused on extending the perception obtained by the onboard sensors, with sensor data received from surrounding vehicles or road side units (RSUs). This way, vehicles generate an enhanced perception of the environment beyond what their own sensors can detect. High-resolution data streams produced by cameras and Lidars impose highly demanding communication requirements. Extended Sensors may require querying data from distant RSUs or vehicles. This could imply communicating with devices located in different countries in a cross-border scenario. Remote driving enables a remote driver or a V2X application to operate a remote vehicle. In this CAM use case, a remote operator takes control of the vehicle when a breakdown or complex environment impedes the autonomous vehicle's trajectory. The remote operator can be located in a different country from the vehicle position, so the constraints on a cross-border context may present operational limitations. Advanced driving implies complex manoeuvres such as overtaking or cooperative collision avoidance that require sharing the driving intentions with the vehicles in proximity. Poor performance of the communication pipeline in terms of latency or reliability may lead to a decrease in the level of automation and/or increase likelihood of accidents. Such a safety-critical use case needs to be tested in as many situations as possible, including roaming or supporting MECs when located in different countries. \begin{table}
\begin{tabular}{c c c} \hline \hline
**5G Technology** & **Reference** & **Added Value** \\ \hline Roaming & [11] & Service continuity in cross-border contexts. \\ Multi-Radio & [14] & Increased interoperability by supporting multiple RATs of cross-border networks. \\ Multi-SIM & [17] & Increased reliability while crossing the border based on SIM redundancy. \\ NR positioning & [19] & Increased positioning accuracy, complementing current sensors and mitigating the positioning error induced by roaming latency. \\ NR sidelink & [22] & Nearby device-to-device communication without the need of a base station. \\ Broadcast \& & [24] & Improved resource efficiency compared to unicast for transmitting common data of interest. \\ mmWave comm. & [27] & Expanded radio capacity. Gigabit-per-second transmission rates. \\ Slicing & [29] & Dedicated slice to support the requirements of a particular cross-border CAM service. \\ Edge & [11] & Offloading computing loads to vehicular edge computing nodes \\ Computing & & via vehicle-to-infrastructure links. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Added value brought by 5G technologies to cross-border connected automated mobility (CAM) services.