Performance Optimization in Vehicular Ad Hoc Networks using a Secure Two-Tier Clustering Framework

Abstract

VANETs are an essential part of Intelligent Transportation Systems (ITS) that allows for efficient Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) communications for traffic management and road safety applications. However, due to high mobility of vehicles, frequent topology change, unstable formation of clusters, continuous election of cluster-heads, increased routing overhead, communication delay and security vulnerabilities occur which deteriorate the network performance. To overcome these challenges, this paper proposes a secure two-tier clustering framework that consists of a Primary Cluster Head (PCH) and a Secondary Cluster Head (SCH) to improve the stability of clusters and reduce the overhead of cluster-head re-election. The Secondary Cluster Head is a backup that takes over leadership immediately if the Primary Cluster Head is unavailable, providing continued communication and better routing efficiency. The framework also utilizes a Certification Authority (CA), Demilitarized Zone (DMZ) and Diffie-Hellman key exchange protocol to enhance communication security, to enable the authenticated access and establishment of secure session keys, and to exclude unauthorized vehicles. The proposed framework was implemented and evaluated under NS-2 simulator using Manhattan mobility model for different vehicle densities. Simulation results demonstrate that the proposed approach obtains better throughput, packet delivery ratio and cluster stability, while lower end-to-end delay, packet loss and routing overhead than conventional single cluster-head clustering schemes. The utilization of secure authentication and proactive cluster management provides a scalable and efficient solution for reliable communication in dynamic VANET environments and makes the proposed framework suitable for next-generation intelligent transportation systems and connected vehicular networks.