Abstract
Pilot-tone assisted log-likelihood ratio (PT-LLR) is derived for low-density parity-check coded, coherent optical orthogonal frequency division multiplexing systems in the presence of linear phase noise. The knowledge of common phase error (CPE) obtained from the pilot-tone is incorporated into the new LLR metric, which eliminates the need for prior CPE estimation and compensation. We compare our metric with the conventional LLR (C-LLR) through extensive simulation using their approximate versions (APT-LLR, AC-LLR). APT-LLR has the same order of complexity as AC-LLR while it outperforms AC-LLR for higher order modulation formats (16-QAM, 64-QAM) at smaller pilot-tone-to-signal power ratios. In addition, we show that with the help of time-domain blind intercarrier interference mitigation, both metrics perform better in the presence of larger laser linewidth.
| Original language | English |
|---|---|
| Article number | 6826532 |
| Pages (from-to) | 1577-1580 |
| Number of pages | 4 |
| Journal | IEEE Photonics Technology Letters |
| Volume | 26 |
| Issue number | 15 |
| DOIs | |
| Publication status | Published - 1 Aug 2014 |
| Externally published | Yes |
Keywords
- common phase error
- LDPC coded OFDM
- linear phase noise
- log-likelihood ratio
- Pilot-tone assisted
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Electrical and Electronic Engineering