Optical Fiber Communication Dispersion Electronic Compensation Base On The Structure Of MLSE Equalizer

Optical fiber communication system has become the main part of moderncommunication network because of its far distance transfer. high channel capacity andhigh transfer rate. As the transfer rate increase from10Gb/s to40Gb/s, even to100Gb/s,the dispersion problem, which is ignored in low transfer rate system is becoming seriously,even become the primary problem to the Fiber Communication system.In high rate fibercommunication system,dispersion will make the transmissive pulse more wide, which willproduce inter-symbol interference(ISI),which will form the bit error and degrade theperformance of system.How to eliminate or minish the dispersion become the keypoint toadvance the transmission rate. Compensate the dispersion become Important Significanceto Optical fiber communication system.Electronic equalization technology with the very board application prospects because ofadvantage of high integrated, low cost, adaptive and flexibility in the future optical fibercommunication.Research about EDC technology include two parts:technologe of linearcompensation and nonlinear compensation. Because of the obvious nonlinear character ofdispersion which exist in the optical fiber comminication system,the Article present anequalizer architecture base on the Volterra series and maximum-likelihood sequenceestimation algorithm in the study of optical fiber dispersion effect and equalizationtechnology.In equalizer,we use Volterra series and LMS adaptive algorithm as an channelestimator,which will get the the parameters of optical channel and pass them to the MLSEparts as the the decision princple for maximum-likelihood branch metric and accumulativebranch metric,then,we use Viterbi algorithm to search the trellis to find the survived routeand then traceback to get the output of equalization.We did the simulation experiment to the equlizer which we mentioned above by thesoftware of Matlab and Optisystem, anlysis the eyediagram and bit error rate before andafter equalization,the results Indicate that the equlizer that we present in the article had agood performance to eliminate the nonlinear dispersion effect in the40Gb/s optical fibercommunication model with the parameter as follow:CD:12ps/nm/km,PMD:0.5ps/km1/2,distance:200km.we anlysis the effect of CD and PMD to the result of equalization andthe affect of different distance at the same time.We found the as the CD and PMDincreased and the distance extend,the effect of the equlizor we present will be affect, that’sbecause the channel estimator we made in MLSE equalizer is based on second orderVolterra series which is inadequate to equalise the accumulative dispersin and high orderresidual dispersion.