新型ldpc算法在高速长距离co-ofdm中应用-application of new ldpc algorithm in high speed and long distance co - ofdm.docxVIP

AbstractWith the rapid development of optical communication technology, the optical Communion-cation of high speed and long distance is becoming the main target of development. But due to the accumulation of noise, the performance of optical communication system will become worse and worse, So FEC(Forward Error Correction) technology has become a very important technology. The research of a low complexity and high performance of FEC code becoming a hot spot in the field of optical communication. The main research of this paper is as follows:First, the author has studied the channel characteristics and noise feature of optical communication, analysis the characteristics and development trend of long distance optical communication system. The noise in optical communications can approximately equivalent to the gaussian white noise. At last ,the author also builds optical communication channel model by VPI, which can be used to simulate the performance of decoding algorithm.Second, The author has studied the performance of common FEC, and introduce the RS (Reed-Solomon codes)coder, BCH(Bose、Ray-Chaudfroid、Hocquenghem ) coder and theRS/BCH cascade code. And simulated these FEC in the optical communication channel of VPI, through the simulation results, the author has proved that the traditional FEC encoding and decoding technology cannot fit to the long distance optical communication system.Third, The author has studied the performance of Turbo and LDPC(Low Density Parity Check Code ） encoding and decoding in optical communication system Respectively.Compared the difference between the LDPC code constructed by Dayan sequence and the LDPC code constructed by Mac kay method. Through the simulation results, the performance of Dayan sequence is better than Mac kay method, But in the long distance optical communication channel of VPI, these two FEC can not make a better performance.Fourth, The author has designed a new LDPC coder without Circle6 based on the Dayan seq