Adaptive Message Prioritization: How to Prioritize VRU Awareness Messages in a Congested V2X Network

The safety of Vulnerable Road Users (VRUs) can be enhanced through the utilization of Vehicle-to-Everything (V2X) communication, enabling the exchange of the VRUs' position and kinematic data. In the European V2X system, the dissemination relies on a dedicated message type, the VRU Awareness Message (VAM), which integrates VRUs into the V2X network as active transceivers. However, in the long term, the high number of V2X nodes transmitting messages poses challenges in the wireless resource allocation, which may result in safety-critical situations. To mitigate this issue, the current standardization of VRU awareness services in Europe, considers clustering VRUs with similar kinematic pattern. Nevertheless, the VRU process for joining a cluster may encounter errors, resulting in high channel load due to multiple requests. In this paper, an adaptive message prioritization is proposed to reduce this impact. This method is triggered only under heavy network load and takes into account the number of potential V2X senders. Via simulations based on a crossing scenario, improvements in network performance are observed, as well as an increase in VRU awareness measured by vehicles, i.e. more VRUs being detected.