SMCRP-IOT: SECURE MULTI-METRIC COOPERATIVE ROUTING PROTOCOL FOR LOW-POWER INTERNET OF THINGS NETWORKS

Abstract

The rapid expansion of low-power Internet of Things (IoT) deployments has intensified the need for secure and energy-efficient routing mechanisms capable of operating under constrained resources. Conventional RPL-based routing methods rely on single or limited metrics, making them vulnerable to energy imbalance, congestion, and selective-forwarding attacks. To address these limitations, this paper proposes SMCRP-IoT, a Secure Multi-Metric Cooperative Routing Protocol that integrates cooperative forwarding with a lightweight security mechanism. The protocol evaluates candidate parent nodes using a composite cost function derived from Expected Transmission Count (ETX), Residual Energy, Hop Count, Queue Occupancy, and Link Stability. A cooperative relay is engaged whenever primary links degrade or when node energy falls below threshold limits, ensuring balanced load distribution. A lightweight symmetric-key integrity check protects routing control messages from tampering without imposing noticeable overhead. SMCRP-IoT is implemented and evaluated in the Cooja simulator across networks of varying sizes. Simulation results demonstrate improved Packet Delivery Ratio, reduced delay, balanced energy consumption, and enhanced network lifetime compared to standard RPL. The findings indicate that incorporating multi-metric decision-making and controlled cooperation significantly strengthens the reliability and resilience of low-power IoT networks.