Soft-decision decoding of differential 16-QAM
US9203558B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 11, 2013 |
| Grant date | Dec 1, 2015 |
| Priority date | — |
| Expiry date | Sep 11, 2033 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/38
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
Methods, systems, and devices are described for soft-decision decoding of data received from optical signals and encoded using a forward error correction (FED) code. A first reliability information is determined for a subset of the bits corresponding to each symbol transmitted using differentially-encoded 16 Quadrature Amplitude Modulation (16-Qam). A second reliability information is determined for a remaining subset of the bits. The first reliability information is based on log likelihood ration (LLR) calculations used for soft-decision FEC decoding of data transmitted using differentially-encoded Quadrature Phase-Shift Keying (QPSK), while the second reliability information is based on LLR calculations used for soft-decision FEC decoding of data transmitted using coherently-encoded 16-QAM. The second reliability information may be pre-calculated and accessed from a lookup table based on a location of the respective symbol in a complex in-phase and quadrature plane. They symbols are then decoded using the two sets of reliability information.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.