DAE-IDS: A Domain-Aware Ensemble Intrusion Detection System with Explainable AI for Industrial IoT Networks

The widespread deployment of Industrial Internet of Things (IIoT) devices creates an urgent need for effective intrusion detection systems (IDS). However, two critical challenges limit current approaches: severe class imbalance in network traffic data that hampers detection of rare attacks, and the “black-box” nature of machine learning models that undermines trust in security-critical applications. This study presents a Domain-Aware Ensemble Intrusion Detection System (DAE-IDS) equipped with explainable AI, addressing both challenges through frequency-aware ensemble learning and computationally efficient interpretability mechanisms. Using the Edge-IIoTset dataset containing 80 features across 12 classes, attacks were categorized into three frequency groups: majority attacks (5 classes), middle-frequency attacks (4 classes), and minority attacks (3 classes). Specialized Random Forest models (50 trees each with class weighting) tailored to each frequency group, then developed a domain-aware ensemble that routes traffic to the most appropriate specialized model based on attack frequency patterns. To enhance interpretability, SHAP explanations added using an optimized approach that combines interventional TreeExplainer with instance subsampling (300 samples per model) and top-k feature prioritization. This optimization reduced SHAP computation time by 60% while maintaining full interpretability. The domain-aware ensemble achieved superior performance with a macro-F1 score of 1.00, demonstrating significant improvements in rare-attack detection compared to traditional approaches. SHAP analysis revealed attack-specific discriminative features, providing action-able insights for security analysts. This framework successfully bridges the accuracy-interpretability trade-off in IIoT security applications, enabling trustworthy intrusion detection suitable for resource-constrained edge environments. The attack-frequency specialization approach offers a practical solution for handling class imbalance while maintaining model transparency through efficient explainability mechanisms.