Error rates of Nyquist-shaped QPSK in cochannel interference and fading
Bibliographic record
Abstract
The use of linear modulation schemes such as quaternary phase shift keying (QPSK) in wireless communication systems has recently received much attention. This is mainly because linear modulation schemes are more spectrally efficient than constant envelope modulation schemes such as Gaussian minimum shift keying modulation (GMSK). The increasing demand for spectrum resources has also motivated interest in using coherent demodulation. We analyze the performance of QPSK in the presence of cochannel interference. Three approaches that can be used for analysing the cochannel interference are investigated. These are a precise method based on the average probability of error, a sum of sinusoids (sinusoidal) model, and a Gaussian interference model. The system performance is assessed in terms of the average bit error rate. The examples consider the outdoor microcellular fading environment. In this environment, the fading experienced by the interfering signals may be represented by a Rayleigh fading model while the fading experienced by the desired signal may be represented by a Ricean or a Nakagami fading model.>
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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 | 0.005 | 0.028 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.002 |
| 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".