Liu Tao, Djordjevic Ivan B
Opt Express. 2014 Dec 29;22(26):32188-98. doi: 10.1364/OE.22.032188.
In this paper, we first describe an optimal signal constellation design algorithm suitable for the coherent optical channels dominated by the linear phase noise. Then, we modify this algorithm to be suitable for the nonlinear phase noise dominated channels. In optimization procedure, the proposed algorithm uses the cumulative log-likelihood function instead of the Euclidian distance. Further, an LDPC coded modulation scheme is proposed to be used in combination with signal constellations obtained by proposed algorithm. Monte Carlo simulations indicate that the LDPC-coded modulation schemes employing the new constellation sets, obtained by our new signal constellation design algorithm, outperform corresponding QAM constellations significantly in terms of transmission distance and have better nonlinearity tolerance.
在本文中，我们首先描述了一种适用于由线性相位噪声主导的相干光信道的最优信号星座设计算法。然后，我们对该算法进行修改，使其适用于由非线性相位噪声主导的信道。在优化过程中，所提出的算法使用累积对数似然函数而非欧几里得距离。此外，还提出了一种低密度奇偶校验（LDPC）编码调制方案，以便与通过所提出算法获得的信号星座相结合使用。蒙特卡罗模拟表明，采用我们新的信号星座设计算法获得的新星座集的LDPC编码调制方案，在传输距离方面显著优于相应的正交幅度调制（QAM）星座，并且具有更好的非线性容忍度。
