Ensuring the safety of Vulnerable Road Users (VRUs) is a critical concern in transportation, demanding significant attention from researchers and engineers. Recent advancements in Vehicle-to-Everything (V2X) technology offer promising solutions to enhance VRU safety. Notably, VRUs often travel in groups, exhibiting similar movement patterns that facilitate the formation of clusters. The standardized Collective Perception Message (CPM) and VRU Awareness Message in ETSI's Release 2 consider this clustering behavior, allowing for the description of VRU clusters. Given the constraints of narrow channel bandwidth, the selection of an appropriate geometric shape for representing a VRU cluster becomes crucial for efficient data transmission. In our study we conduct a comprehensive evaluation of different geometric shapes used to describe VRU clusters. We introduce two metrics: Cluster Accuracy (CA) and Comprehensive Area Density Information (CADI), to assess the precision and efficiency of each shape. Beyond comparing predefined shapes, we propose an adaptive algorithm that selects the preferred shape for cluster description, prioritizing accuracy while maintaining a high level of efficiency. The study culminates by demonstrating the benefits of clustering on data transmission rates. We simulate VRU movement using real-world data and the transmission of CPMs by a roadside unit. The results reveal that broadcasting cluster information, as opposed to individual object data, can reduce the data transmission volume by two-thirds on average. This finding underscores the potential of clustering in V2X communications to enhance VRU safety while optimizing network resources.

翻译：确保弱势道路使用者（VRU）的安全是交通运输中的关键问题，需要研究人员和工程师的高度关注。近期车联网（V2X）技术的进步为提升VRU安全提供了有前景的解决方案。值得注意的是，VRU通常结群出行，表现出相似的运动模式，这有利于形成聚类。ETSI Release 2中标准化的集体感知消息（CPM）和VRU感知消息考虑了这一聚类行为，允许对VRU聚类进行描述。鉴于信道带宽狭窄的限制，选择适当的几何形状来表示VRU聚类对高效数据传输至关重要。本研究对不同几何形状在描述VRU聚类时的效果进行了全面评估。我们引入两个指标：聚类精度（CA）和综合区域密度信息（CADI），以评估每种形状的精确度和效率。除了比较预定义形状外，我们提出了一种自适应算法，可在保持高水平效率的同时优先选择精度最优的聚类描述形状。研究最终展示了聚类对数据传输速率的提升作用。我们使用真实世界数据模拟VRU运动，以及路侧单元对CPM的传输过程。结果表明，与传输单个对象数据相比，广播聚类信息平均可使数据传输量减少三分之二。这一发现凸显了V2X通信中聚类技术在提升VRU安全的同时优化网络资源的潜力。