相干光NFDM通信系统中的理论和性能分析

Theoretical and Performance Analysis for Coherent Optical NFDM Systems

由于长距离光传输系统中常使用的线性复用技术,常将非线性视为一种干扰因素。非线性频分复用(Nonlinear Frequency Division Multiplexing,NFDM)近年来受到广泛关注,这种技术在非线性傅立叶域中对数据进行调制,被视为克服克尔非线性的一种潜在方法。本文详细介绍了相干光NFDM的理论推导和传输过程,并描述了b系数调制的概念和优化设计。在本文中,使用训练序列来实现基于b系数调制的NFDM系统的信道估计,并通过蒙特卡洛仿真进行验证。基于改进后的b系数调制方法相比于传统b系数调制方法具有更低的误码率并且可以传输更远的距离。此外,它的性能明显优于传统的调制反射系数的方法。

Since the linear multiplexing technology is always adopted in long distance optical transmission systems,the nonlinearity is treated as an interference factor.Nonlinear Frequency Division Multiplexing(NFDM)system in that the data are modulated in the nonlinear Fourier domain has received extensive attentions in recent years,and is seen as a potential method to overcome the fiber Kerr nonlinearity.In this paper,theoretical derivation and transmission process of the coherent optical NFDM are described in detail,and the concept and optimal design of the b-coefficient-modulation are presented.Training sequence is adopted to realize the channel estimation of the b-coefficient-modulation-based NFDM system and the effectiveness is verified by Monte Carlo simulations.Simulation results indicate that using the modified b-coefficient-modulation method could achieve a lower bit error rate and a longer transmission distance than the traditional b-coefficient-modulation method.In addition,the performance of the modified b-coefficient-modulation method has an obvious improvement over the traditional methods of modulating the reflection coefficient.