A hybrid ensembling and autoencoder scheme for improving sensing reliability in cognitive radio networks

This paper proposes a hybrid ensemble classifier with denoising autoencoder (ECDAE) framework to address reliability and robustness challenges in cooperative spectrum sensing (CSS) for cognitive radio networks (CRNs). The proposed framework first employs an ensemble classifier (EC) to dynamically reconfigure the sensing time, optimizing performance while minimizing cost. The EC accurately estimates the sensing samples based on target detection probabilities, false alarm rates, and channel conditions. Subsequently, a denoising autoencoder (DAE) eliminates soft-combined energies from false-sensing users (FSUs) before soft fusion. The results show that EC surpasses other methods, including random forest (RFC), neural networks (NN), decision trees (DT), k-nearest neighbors (KNN), Gaussian naive Bayes (GNB), RUSBoost and XGBoost, achieving an F1 score of 99.23%, an accuracy of 99.78%, and a Matthews correlation coefficient (MCC) of 99.6%. Furthermore, optimized sensing time through EC is combined with DAE reconstruction delivers superior sensing performance at the fusion center (FC) producing low error probabilities compared to traditional schemes such as identical gain combination (IGS), highest gain combination (HGS), particle swarm optimization (PSO), differential evolution-based machine learning (DE-ML) and convolutional neural networks (CNN). On average, the ECDAE framework achieves a 99.4% and 98.1% reduction in error probability compared to traditional schemes (IGS, HGS) and a 92.7% to 97.2% reduction compared to advanced methods (PSO, DE-ML, CNN), across all tested SNR conditions and false-sensing attack scenarios. The framework maintains robustness across four distinct false-sensing scenarios: (1) no false sensing (NFS) reporting an low-energy signals, (2) yes false sensing (YFS) reporting consistently an always high-energy signals, (3) opposite false sensing (OFS) reporting an always invert decisions to the true energy states, and (4) yes/no false sensing (YNFS) where FSU randomly alternates between YFS and NFS - ensuring minimal error probabilities in global decisions.