Index Modulation Enhanced NOMA for Opportunistic Spectrum Access
Bibliographic record
Abstract
We propose a structured opportunistic spectrum access scheme, named ON-OFDM-IM, which employs non-orthogonal multiple access with orthogonal frequency division multiplexing and index modulation (OFDM-IM) to enable efficient spectrum reuse. The framework operates in two phases: an anchor transmission (AT) phase and a subsequent opportunistic access phase. During the first phase, anchor transmitters activate only a subset of subcarriers (SCs) and embed information through both the activation pattern and conventional constellation symbols to enhance energy efficiency. In the second phase, unlicensed devices opportunistically utilize the idle SCs left unused in the AT to support device-to-device communication. This article derives mathematical expressions for the spectral efficiency (SE) and bit error rate (BER) of ON-OFDM-IM. Analytical and simulation results confirm that the proposed scheme achieves a favorable trade-off between SE and BER, outperforming conventional benchmark systems.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".