Intelligent Spectrum Sensing: An Unsupervised Learning Approach Based on Dimensionality Reduction
Bibliographic record
Abstract
In Cognitive radio (CR), users take advantage of vacant licensed bands to transmit their data as they become available. Cognitive users employ an autonomous perception-action decision cycle that starts with sensing the activity of licensed users. By using machine learning techniques, CR users can attain their full cognitive potential and smartly detect empty frequency bands. Learning-based CR systems that utilize supervised learning for spectrum sensing require labeled data for model training. Having readily accessible labeled data is a challenging task for CR networks, since it necessitates cooperation between licensed and unlicensed users. In interweave CR networks, such cooperation is not feasible and imposes a significant communication overhead. Motivated by the above, we address the practical limitation of labeled data scarcity in learning-based CR networks by designing a novel unsupervised learning framework for cooperative spectrum sensing based on a Gaussian mixture model (GMM) and principal component analysis (PCA) that uses a small amount of unlabeled data for training and requires no prior knowledge of the radio environment. The system is mathematically simulated, and its performance is evaluated based on various detection performance metrics. According to our findings, our proposed approach outperforms the GMM algorithm and is on par with supervised learning algorithms such as SVM, RF, and DT. Furthermore, the proposed approach is shown to be robust to low SNRs.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".