An Efficient Cluster-Based Routing Protocol for Enhanced Data Delivery and Stability in VANETs: Cluster-Based Ant-Colony Routing With Adaptive Cluster Head

Abstract

Vehicular ad hoc networks (VANETs) are an essential enabler of intelligent transport systems (ITS), facilitating real-time communication among vehicles to enhance traffic safety and mobility. However, challenges such as high node mobility, frequent topology changes, and variable network density continue to impede the design of reliable and efficient routing protocols. This paper proposes CARAC (Cluster-based Ant-colony Routing with Adaptive Cluster Head), a hybrid routing protocol that integrates dynamic clustering using the K-medoids algorithm with Ant Colony Optimisation (ACO) to improve route stability, scalability, and data delivery performance. CARAC forms mobility-aware clusters by grouping vehicles based on spatial proximity and relative velocity. Each node periodically computes a local stability index to evaluate its membership within a cluster, allowing adaptive cluster maintenance. The protocol also incorporates ACO for optimal path selection and utilises Road Side Units (RSUs) as relays when direct communication between cluster heads is not feasible. Simulation experiments conducted in NS-3 with a vehicular network scenario demonstrate that CARAC consistently outperforms benchmark protocols such as AQRV, MetaLearn and CPB. It delivers higher route discovery success, better packet delivery performance, lower latency, and greater throughput. These results validate the advantages of combining clustering, bio-inspired optimisation, and adaptive stability evaluation in VANET routing, positioning CARAC as a robust and scalable solution for next-generation ITS applications.