Self-supervised Learning for Clustering of Wireless Spectrum Activity
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In recent years, much work has been done on processing of wireless spectral data involving machine learning techniques in domain-related problems for cognitive radio networks, such as anomaly detection, modulation classification, technology classification and device fingerprinting. Most of the solutions are based on labeled data, created in a controlled manner and processed with supervised learning approaches. Labeling spectral data is a laborious and expensive process, being one of the main drawbacks of using supervised approaches. In this paper, we introduce self-supervised learning for exploring spectral activities using real-world, unlabeled data. We show that the proposed model achieves superior performance regarding the quality of extracted features and clustering performance. We achieve reduction of the feature vectors size by 2 orders of magnitude (from 3601 to 20), while improving performance by 2 to 2.5 times across the evaluation metrics, supported by visual assessment. Using 15 days of continuous narrowband spectrum sensing data, we found that 17 the spectrogram slices contain no or very weak transmissions, 36 mostly IEEE 802.15.4, 26 proprietary activity, 12 contain only dotted activity, representing LoRA and proprietary transmissions.
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