Feed-forward frequency offset estimation for 32-QAM optical coherent detection.
Feed-forward frequency offset estimation for 32-QAM optical coherent detection.
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DOI：
10.1364/oe.25.008828
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发表时间：
2017-04
期刊：
影响因子：
3.8
通讯作者：
Fei Xiao;Jianing Lu;S. Fu;Chenhui Xie;M. Tang;J. Tian;Deming Liu
中科院分区：
文献类型：
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作者：
Fei Xiao;Jianing Lu;S. Fu;Chenhui Xie;M. Tang;J. Tian;Deming Liu
由于星座点的非矩形分布，传统的基于快速傅里叶变换的频偏估计（FFT-FOE）不再适用于32-QAM信号。在这里，我们报告了一种改进的FFT-FOE技术，通过选择和数字放大后的32-QAM的内部QPSK环的自适应均衡，这被定义为QPSK选择辅助FFT-FOE。仿真结果表明，没有FOE错误发生的FFT大小只有512个符号，当信噪比（SNR）是17.5 dB以上，使用我们提出的FOE技术。然而，对于32-QAM，传统的FFT-FOE方案总是不能容忍错误概率。最后，在B2B传输的情况下，我们提出的FOE方案对于10 Gbaud的双极化（DP）-32-QAM信号能够很好地达到20%的前向纠错（FEC）门限BER=2×10-2。
Due to the non-rectangular distribution of the constellation points, traditional fast Fourier transform based frequency offset estimation (FFT-FOE) is no longer suitable for 32-QAM signal. Here, we report a modified FFT-FOE technique by selecting and digitally amplifying the inner QPSK ring of 32-QAM after the adaptive equalization, which is defined as QPSK-selection assisted FFT-FOE. Simulation results show that no FOE error occurs with a FFT size of only 512 symbols, when the signal-to-noise ratio (SNR) is above 17.5 dB using our proposed FOE technique. However, the error probability of traditional FFT-FOE scheme for 32-QAM is always intolerant. Finally, our proposed FOE scheme functions well for 10 Gbaud dual polarization (DP)-32-QAM signal to reach 20% forward error correction (FEC) threshold of BER=2×10-2, under the scenario of back-to-back (B2B) transmission.