基于四维非线性串扰模型的单跨无中继光传输多维调制设计

Multi-Dimensional Modulation Designing Based on Four-Dimensional Nonlinear Interference Model for Single-Span Optical Transmission System

随着光通信速率需求的不断提高,光纤中的非线性效应成为了限制信道容量增长的主要因素.针对该问题,本文基于四维(Four-Dimensional,4D)非线性串扰模型和几何整形,提出了抗非线性4D调制设计方法.通过在加性高斯白噪声信道(Additive White Gaussian Noise,AWGN)和单跨无中继光纤传输系统中的仿真,详细比较了四类不同调制格式(包括分别针对AWGN信道和光纤信道设计的2D和4D调制格式)的传输性能.数值仿真结果表明,基于4D非线性串扰模型和4D空间联合优化的调制格式不仅有较高的线性整形增益还具有较好的非线性容忍性.以5通道的波分复用传输系统为例,优化得到的NL-4D-1024调制与传统正交幅度调制(QAM)和2D整形调制相比,可以分别减少0.8 dB和0.4 dB的发射功率.

With the increasing demand of optical communication data rate,the nonlinear effect in optical fiber has be⁃come the main factor limiting the growth of channel capacity.To solve this problem,this paper proposed a nonlinearity-tol⁃erant geometrically-shaped(GS)four-dimensional(4D)modulation optimization method is proposed based on the 4D non⁃linear interference(NLI)model.The transmission performance of four different modulation formats(including the 2D and 4D modulation formats designed for additive white Gaussian noise(AWGN)channel and optical fiber channel,respective⁃ly)are compared in detail via the simulation in the AWGN channel and single-span optical fiber transmission systems.The numerical results show that the constellation shaping based on the joint optimization of 4D NLI model and 4D space can not only achieve higher linear shaping gain but also provide better nonlinear tolerance.Taking the 5-channel wavelength divi⁃sion multiplexing transmission system as an example,the optimized NL-4D-1024 format can reduce the transmitted power by 0.8 dB and 0.4 dB compared with the traditional quadrature amplitude modulation(QAM)and 2D-GS modulation,re⁃spectively.