OFDM-PON系统性能优化研究

发布时间：2018-02-26 21:46

本文关键词： 接入网 OFDM-PON LDPC 峰值平均功率比 SLM　出处：《兰州交通大学》2016年硕士论文　论文类型：学位论文

【摘要】：随着未来接入网高速率、大带宽和宽覆盖的迅速发展,正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)以其频谱利用率高,抗窄带干扰能力强以及能够克服信道的频率选择性衰落等优点被通信界认为是解决接入网业务多元化以及带宽受限等问题的可靠技术,在各大数字化通信领域、IEEE802.11无线局域网和4G移动通信系统中已经被广泛应用。为了满足光通信中急速增长的用户信息量以及多元化业务的要求,寻求下一代光接入网的新型技术也势在必行。在PON(Passive Optical Network,无源光网络)系统中加入OFDM技术已成为了光接入网NG-PON2的研究热点之一。相比于其他PON系统,把OFDM技术应用在PON系统中不仅综合了OFDM技术频谱效率高的优势,还使得系统带宽的调度分配方式更加灵活,抗色散能力更强。OFDM-PON系统被认为是解决未来光接入网带宽“最后一公里”瓶颈的主流方案。论文介绍了OFDM技术和OFDM-PON系统的发展历史及研究现状,以及其基本原理和相关技术,重点围绕OFDM-PON系统性能的优化进行了研究。首先把低密度奇偶校验(Low-Density Parity-Check,LDPC)码引入到OFDM-PON系统中,利用LDPC码的高编码增益对系统性能进行优化。通过仿真对OFDM-PON系统中下行传输经未编码、背靠背未编码,以及采用LDPC-OFDM编码调制的性能进行对比,结果显示在20km的单模光纤上LDPC码对OFDM-PON系统的性能有了明显改善。文章中还通过对比研究分析了LDPC码的不同构造方式和不同译码算法对OFDM-PON系统性能的影响。其次论文通过分析OFDM信号产生的高峰值平均功率比(Peak-to-Average Power Ratio,PAPR),研究了光OFDM信号在传输过程中产生的高PAPR对光传输系统的影响。并在已有的峰均比抑制技术论述分析下,论文提出了一种经LDPC编码后的改进选择映射(SLM)法和限幅法联合的方法来抑制OFDM信号的高PAPR,达到抑制光OFDM信号峰均比的目的,实现OFDM-PON系统中发射机的信号的PAPR的抑制,进而通过提高光OFDM信号的质量来改善OFDM-PON系统的性能。通过仿真分析来验证联合改进法的OFDM-PON的下行传输性能,仿真结果显示OFDM-PON系统采用联合改进法能够很好的抑制OFDM信号的峰均比和降低光器件引发的非线性效应,而且改进后的联合法在降低OFDM的高PAPR的基础上,还降低了普通SLM技术引入的边带信息的影响,从而提升系统的性能。
[Abstract]:With the future access network high-speed, large bandwidth and wide coverage of the rapid development of orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexing, OFDM) with its high frequency spectrum utilization, anti interference ability and can overcome the advantages of frequency selective fading channel is considered reliable communication technology to solve the access network business diversification and bandwidth the limitation, in the digital communication field, IEEE802.11 wireless LAN and 4G mobile communication system has been widely used. In order to meet the amount of user information in optical communication and the rapid growth of demand diversification, to seek new technologies in the next generation optical access network is imperative. In PON (Passive Optical Network, passive in addition, OFDM optical network) technology has become one of the hot issues in the field of optical access network NG-PON2. Compared with other PON systems, the OFDM Technology Used in the PON system not only integrated OFDM technology has high spectrum efficiency advantages, also makes the allocation of the bandwidth of the system is more flexible, stronger anti dispersion capability of the.OFDM-PON system is considered to be the mainstream of future optical access network bandwidth scheme to solve the "last mile" bottleneck. This paper introduces the OFDM technology and OFDM-PON system development history and research, as well as its basic principle and related technologies were studied to optimize the focus on the performance of the OFDM-PON system. Firstly, the low density parity check (Low-Density Parity-Check LDPC) code into the OFDM-PON system, improve the performance of the system using high gain encoding of LDPC codes. The simulation of downlink OFDM-PON system by transmission without encoding, encoding are compared and not back-to-back, performance using LDPC-OFDM encoding and modulation. The results showed that in the 20km of the single-mode fiber LDPC code on OFDM-PON The performance of the system have been improved. The comparative study analyzes the influence of different construction methods of LDPC codes and different decoding algorithm on OFDM-PON system performance through the article. Secondly, through the analysis of the OFDM signal generated by the high peak to average power ratio (Peak-to-Average Power Ratio, PAPR), PAPR studied the effects of high light signal generated in OFDM in the transmission process of the optical transmission system. And on the base of the paprreduction techniques of discourse analysis, this paper puts forward an improved LDPC encoding after selective mapping (SLM) method combined with the high PAPR method and limiting method to inhibit OFDM signaling, light to suppress the PAPR of OFDM signals to suppress the signal transmitter in OFDM-PON system PAPR, and the performance by improving the quality of optical OFDM signal to improve the OFDM-PON system. Through the simulation analysis to verify the improvement method of OFDM-PON Downlink transmission performance, the simulation results show that the OFDM-PON system with improved method can suppress OFDM signal good PAPR reduction and nonlinear effect of optical devices caused, and combined with the improved method in reducing the OFDM high on the basis of PAPR, but also reduces the influence of introduction of common SLM technology of side information, thus to enhance the performance of the system.

【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN929.1

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