Frequency-Domain Blind Equalization for Long-Haul Coherent Pol-Mux 16-QAM System With CD Prediction and Dual-Mode Adaptive Algorithm

The combination of polarization-multiplexing (pol-mux) high-order quadrature-amplitude-modulation (QAM) format and non-data-aided (NDA) channel equalization largely enhances the spectral efficiency of the coherent optical systems. In this paper, we present a two-stage frequency-domain equalization method for long-haul coherent pol-mux NDA system with 16-QAM modulation format. Chromatic dispersion (CD) is blindly estimated and compensated in the first stage of the equalizer, while multimodulus-algorithm-assisted decision-directed multimodulus algorithm (MMA-DDMA) is designed for the second stage to further enhance the equalization performance. The proposed algorithms are experimentally demonstrated in a 80-Gb/s coherent 16-QAM system over 800-km fiber transmission and 30-ps mean differential group delay to achieve wide-range precise CD estimation and better equalization performance compared with conventional adaptive algorithms.

[1]  Changyuan Yu,et al.  Decision-Aided Carrier Phase Estimation for Coherent Optical Communications , 2010, Journal of Lightwave Technology.

[2]  Xiang Zhou,et al.  Ultra-High-Capacity DWDM transmission system for 100G and beyond , 2010, IEEE Communications Magazine.

[3]  M. Magarini,et al.  Spectrally Efficient Long-Haul Optical Networking Using 112-Gb/s Polarization-Multiplexed 16-QAM , 2010, Journal of Lightwave Technology.

[4]  S. Savory.  Digital Coherent Optical Receivers: Algorithms and Subsystems , 2010, IEEE Journal of Selected Topics in Quantum Electronics.

[5]  Chen Zhu,et al.  Two-stage frequency domain blind equalization for coherent pol-mux 16-QAM system with CD prediction and dual-mode adaptive algorithm , 2012, IEEE Photonics Conference 2012.

[6]  L.B. Milstein,et al.  A dual-mode algorithm for blind equalization of QAM signals: CADAMA , 1995, Conference Record of The Twenty-Ninth Asilomar Conference on Signals, Systems and Computers.

[7]  R. Kudo,et al.  Coherent Optical Single Carrier Transmission Using Overlap Frequency Domain Equalization for Long-Haul Optical Systems , 2009, Journal of Lightwave Technology.

[8]  Frequency domain multi-modulus blind equalization for coherent 16 QAM polarization-multiplexed system , 2012, 2012 17th Opto-Electronics and Communications Conference.

[9]  Jian Yang,et al.  The multimodulus blind equalization and its generalized algorithms , 2002, IEEE J. Sel. Areas Commun..

[10]  Kazuro Kikuchi,et al.  Adaptive frequency-domain equalization in digital coherent optical receivers. , 2011, Optics express.

[11]  João Cesar M. Mota,et al.  Decision directed adaptive blind equalization based on the constant modulus algorithm , 2007, Signal Image Video Process..

[12]  Chen Zhu,et al.  8$\,\times\,$40-Gb/s Optical Coherent Pol-Mux Single Carrier System With Frequency Domain Equalization and Training Sequences , 2012, IEEE Photonics Technology Letters.

[13]  S. Savory,et al.  Blind Equalization and Carrier Phase Recovery in a 16-QAM Optical Coherent System , 2009, Journal of Lightwave Technology.

[14]  F.N. Hauske,et al.  Precise, robust and least complexity CD estimation , 2011, 2011 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference.