Design Of Metropolitan Area Optical System With Direct Modulation And Direct Detection Based On Turbo Coding Technology

With the increasing demand for optical communication services,the metropolitan area network plays a vital role in the field of telecommunications.Metropolitan area network's efficiency,security and strong support for various businesses enable it to undertake traditional communication business and to deal with various new complex businesses flexibly,so people pay more and more attention from backbone network to metropolitan area network.Turbo code has excellent ability of error correcting.It is almost close to the decoding performance of Shannon's theoretical limit and it's input sequence has random characteristics under the influence of the interleaver.These features make Turbo codes widely used in metropolitan optical communication systems.It can be seen that the design of a high performance optical metropolitan area system based on Turbo coding technology is of great significance to the development of metropolitan optical communication.Based on the research of the basic theory of metropolitan area network and the traditional Turbo encoding and decoding mode,this paper focuses on the improvement of Turbo code,the combination of Turbo codes and multiple modulation modes,and the signal damage compensation in metro optical communication.The main research work of this paper is as follows:1.Proposed a new matching scheme with low complexity encoding Turbo code weight judgment based on the results of the study show that this method simplifies the design of interleaver complexity,change the Turbo codeword weight distribution,and increase the ability of output code weight and enhance its anti interference.2.The direct modulation and direct detection optical metropolitan area system based on Turbo coding technology is designed,and the Turbo code based on the code weight decision is combined with many kinds of modulation.By comparing the simulation of the system without Turbo code,the combination of traditional Turbo code with modulation and the new Turbo code with modulation system,we can get the conclusion that the performance of the new Turbo code with modulation will improve the performance of the system.3.Signal damage processing is added to optical metropolitan area system,including dispersion compensation and static equalization,polarization related damage compensation.Simulation results show that adding appropriate compensation and equalization algorithm can optimize the performance of optical transmission system.