R²Com: Reliable and Resilient Communication in Duty-Cycled SDN-Based WSN for Urban Traffic Monitoring in Intelligent Transportation Systems

Wireless sensor networks (WSNs) are vital for addressing vehicle-related challenges information management, congestion, and safety in Intelligent Transportation Systems (ITS). Ensuring reliable communication is critical, particularly in urban environments where real-time data from roadside infrastructure enhances traffic flow efficiency and safety. This paper proposes R2Com, a reliable and resilient communication protocol for duty-cycled Software-Defined Wireless Sensor Networks (SDWSNs), specifically designed for urban traffic monitoring. By integrating reliable routing and adaptive duty cycling, R2Com ensures low-latency, energy-efficient data exchange between vehicle detection units and traffic control centers. The protocol leverages four attributes: direct trust, recommended trust, signal-to-interference noise ratio, and residual energy, considering their probability distributions to ensure reliability and resilience in the data plane communication. Secondly, the SDN controller calculates these attributes alongside the Expected Duty Cycled Wake-ups (EDC), enhancing reliability through flexible management and low latency. It then assigns communication strategies to each node through reliable nodes and limits the number of forwarding nodes per node to reduce packet duplication. Simulation results demonstrate that the proposed protocol significantly outperforms existing protocols in terms of average energy consumption, packet delivery ratio, average latency, network lifetime, communication overhead, packet success ratio, reliable coverage degree, coverage percentage, traffic density estimation accuracy, and intersection congestion levels.