Practical OFDM signalling for visible light communications using spatial summation
Bibliographic record
Abstract
Visible light communication (VLC) channels leverage solid-state illumination devices to provide a dual role as high-speed communication links. These channels are bandwidth-limited and can have high SNRs. Bandwidth-efficient intensity-modulated/direct-detection (IM/DD) orthogonal frequency-division multiplexing (OFDM) has been considered for VLC systems. Key drawbacks of OFDM in IM/DD channels are its high peak-to-average power ratio (PAPR) as well as the difficulty of implementing power efficient, high current, wideband drivers. In this paper, we propose a new form of IM/DD OFDM termed spatial optical OFDM (SO-OFDM) in which multiple narrowband OFDM signals are transmitted simultaneously from different LEDs and allowed to sum in space. In this way, a conventional OFDM receiver can be employed while having a series of lower power transmitters, each with improved PAPR. Simulation results show that in comparison with conventional IM/DD OFDM, SO-OFDM is more robust to amplifier nonlinearities and can be implemented with more efficient line driver topologies.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
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".