IEEE ACCESS, sa.1, ss.1-15, 2026 (SCI-Expanded, Scopus)
Epileptic EEG signals are inherently non-stationary and nonlinear,
requiring robust signal decomposition and discriminative feature
representations for reliable seizure analysis. Although Variational Mode
Decomposition has attracted growing interest in epileptic EEG studies,
most existing methods rely on fixed parameter settings and are limited
to binary classification, which restricts robustness and
generalizability. This study proposes a systematic, signal-driven
VMD-based EEG classification framework that emphasizes parameter
optimization, reference-guided feature design, and comprehensive
multi-class evaluation. Using the Bonn EEG dataset, the framework is
evaluated across all 26 possible class combinations, spanning binary to
five-class classification scenarios. The effects of key VMD parameters
(K and α) are systematically investigated through grid-based performance
analysis to identify optimal parameter ranges. In addition to
conventional time- and frequency-domain statistical features, novel
reference-based features are introduced by quantifying spectral
divergence and energy-related differences between decomposed signal
components and class-specific reference signals, enabling the capture of
relative and physiologically meaningful spectral characteristics. The
resulting feature sets are evaluated using k-NN, SVM and RF classifiers
under a strict 10-fold cross-validation protocol. Experimental results
show that the proposed reference-based features consistently improve
classification, accuracy and stability, particularly in higher-order
multi-class problems. Statistical analyses confirm that the observed
performance gains over baseline feature models are highly significant.
Notably, the RF classifier achieves an average accuracy of 99.46% across
all 26 class combinations, demonstrating strong generalization
capability. Overall, the proposed framework offers an interpretable,
computationally efficient and provides a promising framework for
epileptic EEG analysis, with potential applicability to biomedical and
wearable EEG systems.