Transmission and reception of duobinary multilevel pulse-amplitude-modulated optical signals using subsequence-based encoder
US6445476B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 29, 2001 |
| Grant date | Sep 3, 2002 |
| Priority date | — |
| Expiry date | Mar 24, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B10/524
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Methods and apparatus to transmit and receive information bits encoded in duobinary, multilevel pulse-amplitude-modulated (PAM) optical signals are described. The transmitted optical signal has a narrow optical spectrum and a low symbol rate. Information bits are encoded in a M-ary PAM symbol sequence, where M≧3. The subsequence-based encoder decomposes the PAM symbol sequence into M1 subsequences, precodes each subsequence, performs duobinary filtering on each precoded subsequence, and forms a weighted sum of the duobinary precoded subsequences. The weighted sum of duobinary precoded subsequences is lowpass filtered and modulated onto an optical electric field. The receiver processes a received optical electric field to obtain an electrical signal proportional to the received optical intensity, and performs M-ary symbol-by-symbol decisions to recover the transmitted information bits, without potential error propagation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.