## 5 V2X Technology in the Context of SAE Levels of Autonomy
### Mapping of V2X Capabilities to the SAE Levels of Autonomy  
In this paper, we propose a mapping of V2X capabilities to the SAE levels of autonomy by utilizing the features provided by communication protocols, integrated into automation levels. * LoA 0--No automation. At Level 0, V2X technology refers to the communication and exchange of information between vehicles and the surrounding infrastructure, including other vehicles, pedestrians, traffic signals and road infrastructure. It enables vehicles to share real-time data such as speed, position and intentions with other connected entities, allowing for enhanced situational awareness [46]. At this level, V2X technology plays a crucial role in providing important safety-related information to the human driver, e.g., warnings about hazardous road conditions, traffic congestion or the presence of emergency vehicles. By transmitting this information, both situational awareness and decision making capabilities are significantly improved. * LoA 1--Driver assistance. The human driver remains engaged and responsible for the driving task, V2X can augment the existing driver assistance features by enabling real-time communication between the vehicles, the infrastructure, and the other entities. In practice, this includes data on the speed and trajectory of nearby vehicles, enabling the automated system to maintain a safe distance and adapt the speed accordingly. At this level, V2X can support cooperative maneuvers and interactions between vehicles, such as cooperative merging or platooning. By exchanging information about trajectory or acceleration, the system can aid the human drivers to coordinate their movements more efficiently and smoothly. * LoA 2--Partial driving automation. V2X communication enables cooperative perception and motion control between the vehicles and the surrounding environment. At this level, the automated system assumes control over both longitudinal and lateral motions, where V2X facilitates the exchange of sensor data between the vehicles. By sharing information about their own sensor readings, such as radar, LIDAR or camera data, vehicles can collectively improve their perception of the surrounding environment, enhancing the object detection, the tracking and the situational awareness, allowing the system to engage in more complex driving scenarios. LoA 2+ systems can also benefit from communicating the intentions of maneuvering functions, such as lane changes, overtaking or merging, to nearby vehicles, enabling smoother and more coordinated movements. This cooperative behavior can enhance safety, reduce the risk of collisions and optimize traffic flow. * LoA 3--Conditional automation. The automated system is responsible for controlling the vehicle and executing the driving task under certain conditions, while the human driver acts as a fallback and is required to intervene when prompted by the system. At this level, vehicle requires data from traffic infrastructure, such as the traffic lights or the road signs, and the other connected entities, including other vehicles and pedestrians, which are traditionally provided by the onboard sensor system. This information can assist the automated system in making informed decisions, adjusting its behavior and enhance the overall situational awareness of the automated system by providing advanced warnings and alerts. V2X communication can support the seamless transition of control between the automated system and the human driver. In case conditions exceed the capabilities of the automated system or require human intervention in the given ODD, V2X technology can facilitate the handover process. * LoA 4--High automation. The automated system is capable of performing all dynamic driving tasks within a specific ODD without requiring human intervention. V2X technology contributes to this high automation level by facilitating the exchange of critical information between the vehicles and the infrastructure, enabling them to share real-time data about intentions, trajectories and sensor readings.