Coded Pulse-Position Modulation for Free-Space Optical Communications
Bibliographic record
Abstract
Multilevel (Q-ary, Q > 2) pulse-position modulation (Q-PPM) with direct detection is a very popular transmission method for power-efficient free-space optical communication systems. The combination of Q-PPM with error-control coding is an effective means to further improve power efficiency. In this paper, we study the application of the multilevel coding (MLC) paradigm to Q-PPM transmission. In particular, we devise a powerful coded Q-PPM scheme which is a simplified version of MLC and which we refer to as reduced-level MLC (RL-MLC). We show how to design and optimize RL-MLC for Q-PPM when using constellation-constrained capacity as the pertinent figure of merit. Furthermore, we provide simulative evidence that RL- MLC with off-the-shelf low-density parity-check codes (LDPC) closely approaches its corresponding capacity limit. For 64-PPM, RL-MLC with only two levels achieves practically the same performance as that of bit-interleaved coded modulation with iterative decoding (BICM-ID), which involves a more difficult design procedure.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| 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".