The widespread adoption of end-to-end encryption in 5G networks limits the effectiveness of traditional intrusion detection systems that rely on payload inspection. This challenge is particularly critical for detecting Advanced Persistent Threats (APTs), which employ low-rate, long-duration, and stealthy communication strategies to evade conventional defenses. This study presents a privacy-preserving intrusion detection framework that operates exclusively on flow-level traffic metadata without deep packet inspection. Network packets are aggregated into bidirectional flows, from which temporal, statistical, and directional features are extracted to characterize behavioral patterns. A Transformer-based model with self-attention is employed to capture long-range dependencies across encrypted traffic sequences and identify subtle, temporally dispersed attack indicators. The framework is evaluated on a large-scale 5G-relevant dataset containing over one million flow records and compared against classical machine learning, ensemble, CNN, and LSTM models. Results demonstrate high recall and strong F1-score in distinguishing APT from benign traffic. Attention-based and feature-level explanations further reveal that prolonged communication, irregular timing gaps, and directional asymmetry significantly influence detection decisions. The findings support the practicality of explainable Transformer models for secure and scalable APT detection in encrypted 5G environments.
Efficient cell association remains a fundamental challenge in fifth-generation (5G) vehicle-to-everything (V2X) systems due to rapid topology changes, heterogeneous deployments, and stringent latency requirements. Conventional learning-based approaches often rely on shallow representations or independent optimization strategies, limiting their adaptability in dense and highly dynamic environments. To address these issues, this study introduces a multi-level graph representation framework that models interactions between vehicles and base stations across hierarchical spatial structures. The proposed approach integrates contextual node embedding with attention-driven graph learning to capture mobility patterns, signal characteristics, and network load dependencies. Additionally, a training-stage optimization mechanism is incorporated to refine attention parameters, improving convergence behavior without increasing inference complexity. The framework is evaluated using a real-world vehicular mobility dataset, demonstrating consistent improvements in association stability, handover reliability, and overall network performance compared with existing deep learning and graph-based methods. Experimental results show gains in accuracy (94.17%) and F1-score (93.93%), indicating enhanced decision robustness under dynamic conditions. Although validation is conducted on an urban dataset, the proposed architecture provides a scalable foundation for adaptive cell selection in next-generation intelligent transportation systems.
E. Krishna, Kamaraj Kanagaraj, N. Reddy et al.· Scientific Reports· 0 citations