Combined oversampling and undersampling method based on slow-start algorithm for imbalanced network traffic

Network traffic data basically comprise a major amount of normal traffic data and a minor amount of attack data. Such an imbalance problem in the amounts of the two types of data reduces prediction performance, such as by prediction bias of the minority data and miscalculation of normal data as outliers. To address the imbalance problem, representative sampling methods include various minority data synthesis models based on oversampling. However, as the oversampling method for resolving the imbalance problem involves repeatedly learning the same data, the classification model can overfit the learning data. Meanwhile, the undersampling methods proposed to address the imbalance problem can cause information loss because they remove data. To improve the performance of these oversampling and undersampling approaches, we propose an oversampling ensemble method based on the slow-start algorithm. The proposed combined oversampling and undersampling method based on the slow-start (COUSS) algorithm is based on the congestion control algorithm of the transmission control protocol. Therefore, an imbalanced dataset oversamples until overfitting occurs, based on a minimally applied undersampling dataset. The simulation results obtained using the KDD99 dataset show that the proposed COUSS method improves the F1 score by 8.639%, 6.858%, 5.003%, and 4.074% compared to synthetic minority oversampling technique (SMOTE), borderline-SMOTE, adaptive synthetic sampling, and generative adversarial network oversampling algorithms, respectively. Therefore, the COUSS method can be perceived as a practical solution in data analysis applications.