Cho Junho, Xie Chongjin, Winzer Peter J
Bell Labs, Alcatel-Lucent, 1649 Sangam-Dong, Mapo-Gu, Seoul 121-904, South Korea.
Opt Express. 2012 Mar 26;20(7):7915-28. doi: 10.1364/OE.20.007915.
Soft-decision forward error correction (SD-FEC) schemes are typically designed for additive white Gaussian noise (AWGN) channels. In a fiber-optic communication system, noise may be neither circularly symmetric nor Gaussian, thus violating an important assumption underlying SD-FEC design. This paper quantifies the impact of non-AWGN noise on SD-FEC performance for such optical channels. We use a conditionally bivariate Gaussian noise model (CBGN) to analyze the impact of correlations among the signal's two quadrature components, and assess the effect of CBGN on SD-FEC performance using the density evolution of low-density parity-check (LDPC) codes. On a CBGN channel generating severely elliptic noise clouds, it is shown that more than 3 dB of coding gain are attainable by utilizing correlation information. Our analyses also give insights into potential improvements of the detection performance for fiber-optic transmission systems assisted by SD-FEC.
软判决前向纠错（SD-FEC）方案通常是为加性高斯白噪声（AWGN）信道设计的。在光纤通信系统中，噪声可能既不是循环对称的也不是高斯分布的，从而违反了SD-FEC设计所基于的一个重要假设。本文量化了这种非AWGN噪声对这种光信道上SD-FEC性能的影响。我们使用条件双变量高斯噪声模型（CBGN）来分析信号两个正交分量之间相关性的影响，并利用低密度奇偶校验（LDPC）码的密度演化来评估CBGN对SD-FEC性能的影响。在产生严重椭圆噪声云的CBGN信道上，结果表明，通过利用相关信息可获得超过3 dB的编码增益。我们的分析还深入探讨了由SD-FEC辅助的光纤传输系统检测性能的潜在改进。
