WDM系统中偏振复用信号的均衡与频谱整形技术的研究

发布时间：2018-06-03 17:05

本文选题：WDM + 自适应均衡　；参考：《电子科技大学》2017年硕士论文

【摘要】：为了满足数据流量爆炸式的增长对通信系统的需求,现有的商用100G以太网逐渐地会被淘汰,400G以太网就是在这个背景下提出的下一代骨干网传输技术。目前正在商用的112Gbps偏振复用-正交相移键控(Polarization Division Multiplexing-Quadrature Phase Shift Keying,PDM-QPSK)传输系统结合了偏振复用以及高阶调制技术,具有集成度高、频谱资源利用率高等特点。在此基础上,本文在研究400G组网技术时采用的是四载波4×112G的波分复用(Wavelength Division Multiplexing,WDM)实现方案,此方案继承了100G网络的优点。此外随着传输速率的提高以及传输距离的增加,光信号中的色散以及非线性效应将会逐渐累积,如果不采取相应的信号补偿技术,将会大大限制光纤通信系统的传输容量。本文首先研究了光纤通信系统中的色散补偿算法。为了补偿光信号中的色散效应,通常在接收端使用自适应时域均衡器的方法进行补偿。然而目前的数字信号处理(Digital Signal Processing,DSP)芯片处理能力无法处理高速率的400G信号,因此流水线结构的均衡器在高速率光纤通信系统中被大量使用。但是与此同时也给自适应均衡器带来了时延,从而影响了均衡器的性能。为了研究反馈时延对自适应时域均衡器的影响,本文提出了采用数理统计在理论上对均衡器的性能进行分析的新方法。首先对均衡器的权值建立数学模型,然后得到均衡器抽头系数的统计数据,进而对均衡器的性能进行分析。本文在此基础上对常用的两种自适应时域均衡算法即最小均方误差以及恒模算法分别进行了分析与比较,研究内容既包括在不同的反馈时延下各种均衡器的收敛速度的比较,还包括对均衡器稳定性的分析。另一方面,针对信道中的非线性效应,本文提出了结合高速数模转换(Digitalto-Analog Converter,DAC)以及模数转换(Analog-to-Digital Converter,ADC)技术研究频谱整形技术对光纤通信系统中非线性效应容忍性的方法。本文使用时域有限脉冲响应(Finite Impulse Response,FIR)滤波器的实现方式,研究并比较了Nyquist,根升余弦脉冲(Root Raised Cosine,RRC),根M型脉冲(Root M-Shaped Pulse,RMP)以及多项式脉冲(Root Polynomial Pulse,RPP)四种不同的频谱整形技术在统一的400G光纤传输系统中对非线性效应的容忍性。最后从DAC量化精度、DAC量化带宽以及ADC采样速率三个方面,开展了DAC和ADC限制对频谱整形技术性能影响的分析。
[Abstract]:In order to meet the demand of communication system due to the explosive growth of data traffic, the existing commercial 100G Ethernet will be eliminated gradually, which is the next generation backbone network transmission technology proposed under this background. The 112Gbps polarization-multiplexing Division Multiplexing-Quadrature Phase Shift keying PDM-QPSK transmission system, which is now commercially available, combines polarization multiplexing and high-order modulation techniques, and has the advantages of high integration and high spectral resource utilization. On this basis, the implementation scheme of wavelength division multiplexing Division multiplexing WDM with four carriers 4 脳 112G is adopted in this paper, which inherits the advantages of 100G network. In addition, with the increase of transmission rate and transmission distance, the dispersion and nonlinear effects in optical signal will gradually accumulate. If the corresponding signal compensation technology is not adopted, the transmission capacity of optical fiber communication system will be greatly limited. In this paper, the dispersion compensation algorithm in optical fiber communication systems is studied. In order to compensate the dispersion effect in optical signals, adaptive time domain equalizer is usually used in the receiver. However, the current digital signal processing (DSP) chip can not process 400G signals at high speed, so pipelined equalizers are widely used in high rate optical fiber communication systems. But at the same time, it also brings time delay to the adaptive equalizer, which affects the performance of the equalizer. In order to study the effect of feedback delay on adaptive time domain equalizer, a new method is proposed to analyze the performance of the equalizer theoretically using mathematical statistics. First, the mathematical model of the equalizer's weight is established, then the statistical data of the equalizer's tap coefficient are obtained, and the performance of the equalizer is analyzed. In this paper, two kinds of adaptive time domain equalization algorithms, minimum mean square error (MSE) and constant modulus algorithm (CMA), are analyzed and compared respectively. The research includes the comparison of convergence rates of various equalizers under different feedback delay. An analysis of the stability of the equalizer is also included. On the other hand, in view of the nonlinear effect in the channel, this paper proposes a method to study the tolerance of spectrum shaping technology to nonlinear effects in optical fiber communication systems by combining high speed digitalto-Analog convertor DAC and Analog-to-Digital conversion ADCtechnology. In this paper, the implementation of finite Impulse response filter in time domain is presented. The tolerance of four different spectral shaping techniques, Nyquist, Root Raised Cosine Raised, Root M-Shaped Pulseus, and polynomial Pulse Root Polynomial RPP, to nonlinear effects in a unified 400G optical fiber transmission system is studied and compared. Finally, from three aspects of DAC quantization precision, quantization bandwidth and ADC sampling rate, the influence of DAC and ADC constraints on the performance of spectrum shaping technology is analyzed.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.11

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