Title :
Differential Phase-Based Frequency Offset Estimation for 16-QAM Coherent Optical Systems
Author :
Yumin Liu ; Yunfeng Peng ; Yuhong Zhang ; Yuhan Liu ; Zhizhong Zhang
Author_Institution :
Beijing Eng. & Technol. Res. Center for Convergence Networks & Ubiquitous Services, Univ. of Sci. & Technol. Beijing, Beijing, China
Abstract :
This letter presents a novel differential phase-based frequency offset estimation algorithm for square 16-ary quadrature amplitude modulation coherent optical systems. Different from the existing algorithm using only consecutive Class I symbols (CCIS), all the constellation points (i.e., both Class I and Class II symbols) are used here to estimate frequency offset. By considering the compatibility of symbols in different Class, eighth power operation is implemented to remove the modulated data phase, before which rotating by π/8 is needed for Class II symbols. Simulation results show that the proposed algorithm leads to 0.7-dB signal-to-noise ratio per symbol improvement at bit-error rate of 10-3 due to its high estimation accuracy compared with the conventional CCIS scheme.
Keywords :
error statistics; optical receivers; quadrature amplitude modulation; 16-QAM coherent optical systems; Class II symbols; bit-error rate; consecutive Class I symbols; constellation points; conventional CCIS scheme; differential phase-based frequency offset estimation algorithm; estimation accuracy; modulated data phase; noise figure -0.7 dB; power operation; signal-to-noise ratio; square 16-ary quadrature amplitude modulation coherent optical systems; symbol compatibility; symbol improvement; Accuracy; Bit error rate; Educational institutions; Estimation; Frequency estimation; Optical receivers; Signal to noise ratio; Coherent optical receiver; differential phase; frequency offset estimation; quadrature amplitude modulationdifferential phase;
Journal_Title :
Photonics Technology Letters, IEEE
DOI :
10.1109/LPT.2014.2359178
