Turbo码与RS-Turbo级联编码在光正交频分复用系统中的应用

发布时间：2018-01-10 14:10

本文关键词：Turbo码与RS-Turbo级联编码在光正交频分复用系统中的应用　出处：《天津理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：光正交频分复用技术(OOFDM)做为长距离、高速率、大容量光通信传输系统的一种关键技术成为了研究的热点。但是由于光纤非线性,信号的高峰均功率比(PAPR)以及光放大器的自发辐射噪声(ASE)等的存在,对系统的误码率性能产生了严重的影响。因此,本文通过理论分析和仿真对OOFDM系统进行了研究并提高系统的误码率(BER)性能。本文的主要内容如下:1.介绍OFDM、OOFDM以及编码等技术的发展情况和研究现状。2.介绍本文需要用到的基本原理。如OFDM原理、Turbo码和RS码的编解码原理。3.建立了一个采用Turbo编码的直接检测光正交频分复用系统,比较分析了编码系统与未编码系统的传输性能。在编码系统中采用了三种解码算法,分别为:Log-MAP,Max-Log-MAP和Threshold Max-Log-MAP。通过比较三种解码算法,发现使用Max-Log-MAP算法时,系统的误码率性能最好。在传输距离为240km时,传输速率为30Gb/s的未编码系统的误码率达到10-3数量级时,光信噪比要达到24dB,而传输速率为50Gb/s的Turbo编码系统,达到同样误码率性能时,光信噪比只需达到20dB。4.将RS-Turbo级联编码应用到相干光正交频分复用系统中。对于RS-Turbo级联码,采用了码率为1/2的Turbo码和RS(186,166,8)。Turbo码的解码算法采用了两种,分别是Max-Log-MAP算法和Log-MAP算法,RS码解码采用了迭代BM算法。仿真结果显示,采用RS-Turbo级联编码的CO-OFDM系统的误码率性能在高光信噪比时有明显改善,与采用Turbo编码的系统相比,迭代次数明显减少。另外,当Turbo码采用Max-Log-MAP算法解码时,采用RS-Turbo级联编码的CO-OFDM系统可以无差错传输400km,而采用Turbo编码的系统在误码率低于10-4数量级时只能传输240km。5.搭建了基于相干光正交频分复用和PDM(Polarization Division Multiplexing)的WDM(Wavalength Division Multiplexing)系统,并将Turbo码和RS-Turbo级联编码应用到系统中,仿真证明在光信噪比为22dB时,可以实现200Gb/s数据的无误码传输。
[Abstract]:Optical orthogonal frequency division multiplexing (OOFDM) technology for long distance, high rate, a key technology of large capacity optical communication system has become a hot research. But because the optical nonlinearity, signal peak to average power ratio (PAPR) and optical amplifier spontaneous emission noise (ASE) such as the existence of the a serious impact on the BER performance of the system. Therefore, this paper through theoretical analysis and Simulation of OOFDM system are researched and improved the system bit error rate (BER) performance. The main contents of this paper are as follows: 1. introduction of OFDM,.2. and the current situation of the development of OOFDM and encoding technology this paper introduces the basic principle to use such as OFDM. The principle of coding and decoding principle of.3. Turbo code and RS code is established using a Turbo encoding a direct detection optical orthogonal frequency division multiplexing system, a comparative analysis of the transmission performance of encoding system and encoding system. Not in the series The code system adopts three decoding algorithms, respectively: Log-MAP, Max-Log-MAP and Threshold Max-Log-MAP. by comparing the three kinds of decoding algorithm, using Max-Log-MAP algorithm, the BER performance of the system. In the best transmission distance is 240km, the transmission rate of 30Gb/s encoding system without bit error rate of 10-3 magnitude, reach the 24dB ratio of optical signal to noise, and the transmission rate of Turbo encoding 50Gb/s system, achieve the same BER performance, the optical signal-to-noise ratio only reaches 20dB.4. the RS-Turbo cascade encoding applied to coherent optical orthogonal frequency division multiplexing system. For the RS-Turbo concatenated code, the 1/2 code rate Turbo code and RS (186166,8) decoding algorithm of.Turbo codes with two, respectively Max-Log-MAP and Log-MAP algorithm, RS decoding using the iterative BM algorithm. The simulation results show that the CO-OFDM system with RS-Turbo cascade encoding error Rate performance at high optical SNR is improved obviously, compared with the system using Turbo encoding, the number of iterations was significantly reduced. In addition, when the Turbo code decoding using Max-Log-MAP algorithm, using CO-OFDM encoding system RS-Turbo cascade can be error free transmission of 400km, and the Turbo encoding system at a bit error rate of 10-4 level only transmission of 240km.5. to build a coherent optical orthogonal frequency division multiplexing and PDM (Polarization Division Multiplexing) based on WDM (Wavalength Division Multiplexing) system, and the Turbo code and RS-Turbo concatenated encoding is applied to the system, simulation results show that in the optical signal-to-noise ratio is 22dB, can achieve 200Gb/s data transmission without error.

【学位授予单位】：天津理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN911.22

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