Open AccessSub-symbol-rate sampling for PDM-QPSK signals in super-Nyquist WDM systems using quadrature poly-binary shaping
Author(s) -
Cheng Xu,
Guanjun Gao,
Sai Chen,
Jie Zhang,
Ming Luo,
Rong Hu,
Qi Yang
Publication year - 2016
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.24.026678
Subject(s) - phase shift keying , quadrature amplitude modulation , symbol rate , quadrature (astronomy) , polarization division multiplexing , optics , keying , computer science , electronic engineering , nyquist rate , sampling (signal processing) , multiplexing , amplitude and phase shift keying , channel spacing , wavelength division multiplexing , algorithm , bit error rate , physics , channel (broadcasting) , telecommunications , wavelength , engineering , detector
We compare the performance of sub-symbol-rate sampling for polarization-division-multiplexed quadrature-phase-shift-keying (PDM-QPSK) signals in super-Nyquist wavelength division multiplexing (WDM) system by using quadrature duo-binary (QDB) and quadrature four-level poly-binary (4PB) shaping together with maximum likelihood sequence estimation (MLSE). PDM-16QAM is adopted in the simulation to be compared with PDM-QPSK. The numerical simulations show that, for a software defined communication system, the level number of quadrature poly-binary modulation should be adjusted to achieve the optimal performance according to channel spacing, required OSNR and sampling rate restrictions of optics. In the experiment, we demonstrate 3-channel 12-Gbaud PDM-QPSK transmission with 10-GHz channel spacing and only 8.4-GSa/s ADC sampling rate at lowest. By using QDB or 4PB shaping with 3tap-MLSE, the sampling rate can be reduced to the signal baud rate (1 samples per symbol) without penalty.