TFD-CAD: Collaborative time-frequency dual-branch framework for time series anomaly detection
摘要
Unsupervised anomaly detection in multivariate time series is critical for the reliability of the Industrial Internet of Things (IIoT) and IT operations. However, existing reconstruction-based approaches struggle with anomaly contamination, complex dependency modeling, and non-stationary interference. To address these challenges, this paper proposes TFD-CAD, a novel Collaborative Time-Frequency Dual-Branch Anomaly Detection framework. Distinct from methods that process domains in isolation, TFD-CAD introduces a collaborative masking mechanism where temporal features explicitly guide high-frequency masking to purify representations against contamination. To capture intricate dependencies, a multi-scale fusion module is designed within the frequency branch to model intra-band details and inter-band harmonic correlations simultaneously. Furthermore, non-stationarity is addressed via a residual-focused reconstruction strategy. By leveraging time-series decomposition and static memory-guided attention entropy regularization, the model effectively disentangles legitimate macro-trends from anomalies. Extensive experiments on multiple real-world benchmark datasets demonstrate that TFD-CAD achieves state-of-the-art performance, significantly outperforming existing baselines in terms of detection accuracy and robustness.