【作者】 李潇；

【导师】 季伟；

【作者基本信息】 山东大学 ， 电磁场与微波技术， 2017， 硕士

【摘要】 根据下一代光接入网的发展方向:更高的接入带宽、更远的传输距离、更大的分光比以及带宽资源的灵活、动态分配,WDM-OFDMA-PON可以很好地满足这些发展要求。PON是光纤接入的主要网络结构,近年来发展的LR-PON(Long Reach-PON)符合接入网对更远传输距离的要求,以及接入网/城域网融合的发展趋势。WDM技术带来了更高的带宽。OFDM技术带来更灵活的多址方式和资源分配粒度,而灵活频谱技术则实现了网络带宽资源的动态、弹性分配。随着接入网与城域网的融合以及基于SDN技术实现动态灵活栅格的光网络的趋势,下一代光接入网中的高级调制格式,损伤补偿,网络生存性成为有待解决的关键问题。本论文在频谱灵活的WDM-OFDMA-PON网络的基础上,提出了高效的调制格式,光信号传输损伤感知的评价模型及采用DSP动态补偿机制,设计了低成本的光网络故障监测方案,并对以上设计进行全面、深入的研究分析及方案优化。其成果将为下一代光接入网中光信号传输与优化提供理论依据和技术支持。论文的主要工作与创新如下:(1)介绍了光网络的发展动态与下一代基于PON的光接入网的发展趋势:基于LR-PON的城域/接入融合网络,OFDM技术与PON技术的结合,SDN技术与PON技术的结合,DSP技术在光接入网中的广泛应用。在此基础上分析了下一代光接入网中为提高可靠性需要解决的关键问题。(2)介绍了 QPSK调制格式的基本原理,数学模型,并详细分析了PM-QPSK-ROF系统的工作原理,在此基础上,提出了改进后的PS-QPSK调制格式,通过仿真,对比了两种调制格式的性能:星座图,EVM与功率的关系,EVM/BER与IQ失衡的关系,证实所提出的PS-QPSK调制格式的抗IQ失衡与XPM的能力要比PM-QPSK 强。(3)介绍了OFDM调制格式的原理与数学表达以及IFFT/FFT实现,并分析了光通信中的两种OFDM系统的结构与各自优缺点。提出了改进后的RZ-QPSK-OFDM调制格式,并详细研究了其原理。通过把子载波分奇数偶数子载波分别进行IFFT运算处理,合成到一起后调制为光信号在光纤中传输。此外对RZ-OFDM-QPSK,NRZ-以及改进后的RZ-调制格式在ROF系统中进行了对比分析,通过仿真结果,验证了所提出的调制格式的频谱利用率与NRZ调制格式相当,是同等条件下RZ调制格式的2倍,且传输性能要好于NRZ调制格式。(4)对光信号传输过程中所造成的损伤包括:色度色散,偏振模色散,IQ失衡,相位噪声,以及非线性效应进行理论分析。并给出了优化后的关联式损伤感知评估模型,采用Q因子作为评价标准考虑了损伤之间的作用,不同损伤的权重以及性能余量的影响。对于主要的损伤,研究了补偿方案,并通过仿真验证了补偿机制的有效性。(5)在光网络生存性方面,在网状网加树的结构中,提出了低成本的光迹监测与光编码检测的联合检测算法,采用光编码技术检测环上链路与节点,然后用光迹监测算法监测网状网的内部链路,通过仿真结果验证了监测算法的有效性与可靠性,此外,还优化了光迹算法中的部分参数,使得启发式的MTA算法输出更小数目的光迹数目,从而进一步降低成本。更多还原

【Abstract】 According to the development direction of next-generation optical access network:higher access bandwidth,farther transmission distance,greater splitting ratio and flexible bandwidth resources allocation,the WDM-OFDMA-PON based on network survivability design can be a good to satisfy these development requirements.PON is the main network structure of fiber access network.In recent years,the development of LR-PON(Long Reach-PON)conforms to the requirements of the next-generation access network for farther transmission distance and the integration of metro-access network.WDM technology provides higher bandwidth.OFDM technology enables more flexible multiple access and finer resource allocation granularity,and flexible spectrum technology realizes the dynamic and flexible allocation of network bandwidth resources.With the integration of access network and metro network and the trend of optical network development based on SDN technology,the advanced modulation format,impairments awareness and compensation,and network survivability of next generation access network become key problems to be solved.Based on the WDM-OFDMA-PON network with flexible spectrum,the author proposed efficient modulation schemes,optical signal transmission impairments awareness and evaluation model,as well as dynamic compensation mechanism by DSP technology.A low-cost optical network fault monitoring scheme in the optical network is also designed,and the comprehensive and in-depth research analysis and the scheme optimization are carried out.The results will provide the theoretical basis and technical support for the optimization of signal transmission in the next generation optical access network.The main work and innovation of this thesis are as follows:(1)The thesis introduces the development optical network and the trend of next-generation PON-based optical access network:the metro-access network integration based on LR-PON,the combination of OFDM technology and PON technology,the combination of SDN technology and PON,and the wide application of DSP Technology in optical access network.On this basis,the author analyzed the key problems for improving reliability in the next generation optical access network.(2)The basic principle and mathematical model of QPSK modulation scheme are introduced,and the working principle of PM-QPSK-ROF system is analyzed.An improved PS-QPSK modulation scheme is proposed.The performance compares between the two modulation formats in terms of constellation,EVM versus power.EVM/BER versus IQ imbalance,and the simulation results confirm that the proposed PS-QPSK modulation format is more resistant to IQ mismatch and XPM than PM-QPSK.(3)The principle and mathematical expression of OFDM modulation format and IFFT/FFT implementation are introduced,and the advantages and disadvantages of two kinds of OFDM systems are analyzed.An improved RZ-QPSK-OFDM modulation scheme is proposed and its principle is studied in detail.The even subcarriers and odd subcarriers are processed by IFFT respectively,and then they are combined to be modulated into optical signals for transmission in the optical fiber.By sub-carrier sub-odd-numbered subcarriers,the subcarriers are processed together and then modulated into optical signals for transmission in optical fiber.In addition,the RZ-OFDM-QPSK,NRZ-and the improved RZ-modulation scheme are compared and analyzed in the ROF system.The simulation results show that the proposed scheme has similar spectrum utilization with the NRZ modulation,and it is 2 times of the parameter for RZ modulation format.Besides high spectrum utilization,the transmission performance is better than the NRZ modulation format.(4)The damage caused by optical signal transmission in the fiber including:chromatic dispersion,polarization mode dispersion,IQ imbalance,phase noise,and nonlinear effects are analyzed in theory.The optimized associated impairments awareness evaluation model using Q factor is shown.The influence of interaction among different impairments,different weight parameters and the network margin is considered.For the main damage,the compensation schemes are studied,and the effectiveness of the compensation mechanisms are verified by simulation.(5)In the aspect of optical network survivability,a joint low-cost monitoring algorithm combining monitoring trail scheme and optical coding scheme is proposed in the mesh and tree network.The link and node on the ring are monitored by optical coding scheme,and other optical links are monitored by m-trail scheme.The simulation results verify the good performance of the monitoring algorithm.In addition,the author optimized some parameters in the heuristic MTA algorithm.which enables less numbers of m-trails and reduces costs.更多还原