Selective bit mapping for Chinese DTMB LDPC coded QAM modulation scheme
Bibliographic record
Abstract
In this paper, we introduce selective-bit mapping to improve the performance of the LDPC coded QAM modulation scheme for Chinese Digital Terrestrial Television Broadcasting (DTMB) system. The threshold of message-passing decoding can be lowered by matching the binary components of LDPC codeword to the positions in the m-tuples to be mapped into 2mQAM symbols. By our approach, the pattern of mapping is described by bit-mapping polynomials, based on which density evolution using Gaussian approximation can be applied. We optimize the bit mapping polynomials for the LDPC codes of the Chinese DTMB standard. Numerical results illustrate that by the proposed approach the decoding threshold can be lowered by 0.05dB to 0.499dB by different combinations of code rate and order of QAM modulations. Simulation results show that the actual BER improvement varies from 0.09dB to 0.6dB in single-carrier and OFDM modes.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| 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".