## 5 V2X Technology in the Context of SAE Levels of Autonomy
### V2X Aided Use Cases of Automated Driving  
Through the implementation of wireless communication infrastructure, various applications leveraging V2X technology for autonomous vehicles have been explored, demonstrating notable attributes such as reliability, efficiency and security. State-of-the-art literature highlights numerous specific V2X-enabled cooperative autonomous driving scenarios, among which automated valet parking, intersection control and cooperative platooning are the most commonly cited use cases [47]. These scenarios encompass common urban road situations like valet parking and intersections, as well as cooperative platooning primarily \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{No Automation} & Level 0 & Level 1 & Level 2 & Level 3 & Level 4 & Level 5 \\  & Driver & Partial driving & Conditional & High & & Full automation \\  & assistance & automation & automation & automation & automation & Full automation \\ \hline Smart infrastructure & ✗ & ✗ & ✗ & ✗ & ✓ & ✓ \\ \hline Driving strategy & ✗ & ✗ & ✗ & ✗ & ✓ & ✓ \\ \hline Decision making & ✗ & ✗ & ✗ & ✓ & ✓ & ✓ \\ \hline Collaborative driving & ✗ & ✗ & ✓ & ✓ & ✓ & ✓ \\ \hline Driver support & ✗ & ✓ & ✓ & ✗ & ✗ & ✗ \\ \hline Driver warning & ✓ & ✓ & ✓ & ✓ & ✗ & ✗ \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Applicability of V2X at various levels of automation based on system complexity. At lower levels of automation, the contribution of V2X technology manifests in driver assistance and raising situational awareness. As the contribution of the human driver decreases at higher levels beyond driver assistance, the focus of information sharing between the vehicle and the environment shifts towards more complex automated functionalities. Table legend: ✗ Applicable \(\star\) Optional \(\star\) Not applicable. considered on regular highways. Existing studies addressing different applications in this domain are typically categorized based on the target objects or locations, the maneuvers involved, and the associated algorithms employed. Automated Valet Parking (AVP) is an advanced parking assistance system that leverages V2X communication to provide a driver-free parking service. AVP integrates real-time information, such as the availability of parking slots, the bookings by other vehicles, and the route plans, to assist drivers through wireless networks. The AVP system takes over the vehicle and manages the entire parking procedure, including the route planning, the execution and the parking. When the driver requests their vehicle, the system autonomously returns it to the transfer place. Due to the properties of AVP listed above, these systems are generally categorized into SAE Level 4 high automation solutions. Regarding serving targets, AVP systems cater to automated vehicles or a combination of regular and automated vehicles. Parking management, coordination of multiple vehicles, and addressing conflicts pose an entry point for V2X communication. Additionally, this allows the exploration of mixed traffic parking garages equipped with AVP, considering the parking requests from vehicles with varying automation levels [48]. Cooperative platooning is another example of LoA 3/4 automated driving use cases, where a group of vehicles travel together in a coordinated manner, with one vehicle acting as the leader and the others as members. Common driving operations within a platoon include acceleration, deceleration and lane-changing to maintain a stable and safe distance between the vehicles. Cooperative platooning aims to enhance traffic efficiency, capacity, driver convenience and to reduce fuel consumption. In practice, driving functions cover various operations to form, maintain and split platoons, control maneuvers within platoons and the algorithms employed for these maneuvers. Cooperative platooning is particularly beneficial when assisted by V2X equipment, as human-driven vehicles can show high uncertainty and randomness.