Adaptive Boundaries Scheme for Cycle-Slip Mitigation in C-mQAM Coherent Systems

Author

Rodrigo Navarro, Jaime ; Pang, Xiaodan ; Kakkar, Aditya ; Ozolins, Oskars ; Schatz, Richard ; Jacobsen, Gunnar ; Popov, Sergei

Author_Institution

Network and Transmission Laboratory, Acreo Swedish ICT AB, Kista, Sweden

Volume

27

Issue

20

fYear

2015

Firstpage

2154

Lastpage

2157

Abstract

We propose a method for cycle-slip mitigation in circular multilevel quadrature amplitude modulation (C-mQAM) coherent optical systems, with constellation rotational asymmetry, based on an adaptive boundaries approach. The impact of cycle-slips in C-mQAM coming from Viterbi–Viterbi algorithm limits the phase noise tolerance. By introducing adaptive boundaries and a differential coding scheme, the ambiguity of asymmetrical rotation of constellation can be effectively removed. Performance of the proposed method is evaluated for a C-16QAM and C-64QAM for various laser linewidths. Results show a noticeable improvement in linewidth symbol duration product ( $\\Delta \\nu \\cdot T_{S})$ tolerance compared with the previous studies on C-mQAM and mQAM constellations. The $\\Delta \\nu \\cdot T_{S}$ tolerance reaches $4 \\times 10^{-4}$ and $1.1 \\times 10^{-4}$ for C-16QAM and C-64QAM, respectively, for 1 dB penalty at a symbol error rate of $10^{-3}$ .

Keywords

Decoding; Encoding; Optical noise; Phase noise; Phase shift keying; Quadrature amplitude modulation; Signal to noise ratio; Carrier phase estimation; circular quadrature amplitude modulation; coherent optical communications; differential decoding;

fLanguage

English

Journal_Title

Photonics Technology Letters, IEEE

Publisher

ieee

ISSN

1041-1135

Type

jour

DOI

10.1109/LPT.2015.2455234

Filename

7155520