Low-Complexity Carrier Phase Recovery Based on Constellation Classification for M-ary Offset-QAM Signal

Low-complexity carrier phase recovery (CPR) for M-ary offset quadrature amplitude modulation (OQAM) formats is proposed and numerically verified, based on the technique of constellation classification. Although the OQAM signal has very poor tolerance to the laser linewidth due to the phase noise-induced crosstalk, we find that both even and odd samples of OQAM signal only have conventional constellation rotation with respect to phase noise. Through linear fitting of the classified constellation, carrier phase estimation can be derived from the slope of linear fitting function. Compared with our recently proposed modified blind phase search scheme, the computational complexity (CC) of proposed CPR does not increase much with the OQAM modulation level of M. Taking the CPR of 16-OQAM into account, we show that the CC can be significantly reduced by a factor of 8.47 (or 7.34) in the form of multipliers (or adders) with performance comparable to MBPS (B = 24) under the condition of Δf × TS = 5 × 10-6. In particular, a tolerance of linewidth and symbol duration product of 8 x 10-5, under the condition of CD = 300 ps/nm and DGD = 10 ps, can be secured for 16-OQAM, given 0.7-dB required-OSNR penalty.

[1]  Jessica Fickers,et al.  Multicarrier Offset-QAM for Long-Haul Coherent Optical Communications , 2014, Journal of Lightwave Technology.

[2]  Ming Tang,et al.  Feed-forward carrier phase recovery for offset-QAM Nyquist WDM transmission. , 2015, Optics express.

[3]  T Pfau,et al.  Phase-Noise-Tolerant Two-Stage Carrier Recovery Concept for Higher Order QAM Formats , 2010, IEEE Journal of Selected Topics in Quantum Electronics.

[4]  M. Seimetz Laser Linewidth Limitations for Optical Systems with High-Order Modulation Employing Feed Forward Digital Carrier Phase Estimation , 2008, OFC/NFOEC 2008 - 2008 Conference on Optical Fiber Communication/National Fiber Optic Engineers Conference.

[5]  Chao Li,et al.  Experimental demonstration of 110-Gb/s unsynchronized band-multiplexed superchannel coherent optical OFDM/OQAM system. , 2013, Optics express.

[6]  J. Kahn,et al.  Digital Equalization of Chromatic Dispersion and Polarization Mode Dispersion , 2007, Journal of Lightwave Technology.

[7]  S. Chandrasekhar,et al.  Study of multicarrier Offset-QAM for spectrally efficient coherent optical communications , 2011, 2011 37th European Conference and Exhibition on Optical Communication.

[8]  Yuefeng Ji,et al.  A Simplified Feedforward Carrier Recovery Algorithm for Coherent Optical QAM System , 2011, Journal of Lightwave Technology.

[9]  Ming Tang,et al.  Nyquist WDM superchannel using offset-16QAM and receiver-side digital spectral shaping. , 2014, Optics express.

[10]  J. Fickers,et al.  Multicarrier offset-QAM modulations for coherent optical communication systems , 2014, OFC 2014.

[11]  Jian Zhao,et al.  DFT-based offset-QAM OFDM for optical communications. , 2014, Optics express.

[12]  Bernhard Spinnler,et al.  Equalizer Design and Complexity for Digital Coherent Receivers , 2010, IEEE Journal of Selected Topics in Quantum Electronics.

[13]  J. Zhao,et al.  Offset-QAM based coherent WDM for spectral efficiency enhancement. , 2011, Optics express.

[14]  R. Noe,et al.  Hardware-Efficient Coherent Digital Receiver Concept With Feedforward Carrier Recovery for $M$ -QAM Constellations , 2009, Journal of Lightwave Technology.

[15]  S. Chandrasekhar,et al.  Generation of 224-Gb/s multicarrier offset-QAM using a real-time transmitter , 2012, OFC/NFOEC.

[16]  Zhuhong Zhang,et al.  Chromatic Dispersion Estimation in Digital Coherent Receivers , 2011, Journal of Lightwave Technology.

[17]  B. Lankl,et al.  Low complexity carrier recovery for coherent QAM using superscalar parallelization , 2010, 36th European Conference and Exhibition on Optical Communication.

[18]  Jian Zhao,et al.  Channel estimation in DFT-based offset-QAM OFDM systems. , 2014, Optics express.

[19]  S. Savory,et al.  Laser Linewidth Tolerance for 16-QAM Coherent Optical Systems Using QPSK Partitioning , 2010, IEEE Photonics Technology Letters.

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