Research On O-OFDM Technology And System Simulaiton

Optical orthogonal frequency division multiplexing (O-OFDM) is a newcommunication technology.The basic idea is to apply OFDM technology into optical fibercommunication. We show that optical OFDM combines the merits of coherent and OFDMtechnologu.Thus,it can constructed high-speed, large capacity and low cost optical OFDMtransmission system. Compared with the traditional optical communication technology, thesystem has the stronger ability to resist dispersion and nonlinear effect of optical fiber.Besides,it is easier to upgrade and make expansion.So people pay attention to it in last foryears.First of all, the article has introduction of recent development of optical fibercomunincation,and the basic principle and OFDM application field are stated. Next, thetwo basic forms of O-OFDM are described: direct detection optical OFDM (DDO-OFDM)system and coherent optical OFDM (CO-OFDM) system. The system combinesMATLAB software with OptiSystem to construct simulation platforms for the two systems,and we analysis of the performance of the two systems deeply on the basis platforms.Firstly,theoretical analysis on mapping mode of DDO-OFDM system is presented.The mapping methods of DDO-OFDM ,which are linear mapping and nonlinear mappingare discussed respectively.Then, transmission performance and BER performance ofDDO-OFDM system are discussed by simulation platform.In other words,we research onconnection of bit error rate (BER), coupled optical power,transmission distance andoptical Signal to noise ratio.Secondly, it elaborates operating principle of CO-OFDM and the performance of eachmodule,and simulates the transmission performance and BER performance of CO-OFDMon different modulation.Thirdly,the key technologies of O-OFDM system are researched,and the method tocompensate phase offset is proposed. Compensation of phase shift is used to correct randomness phase noise due to dispersion effect. The randomness noise which is relatedwith signal frequency and the other random noise are discussed respectively.Thesimulation result confirms that the compensation method has good feasibility andeffectiveness.Forthly,Synchronization problem is studied.It is only to deliberate the affect causedby timing synchronization offset,on optical OFDM system,because it is a simulationsystem not a real system.Detailed discussion of the synchronizations are simulated onO-OFDM,which are Schmidl&Cox and Minn algorithm.The result shows that theperformance is improved.Finaly,the optical OFDM system adopts amplitude-limited to reduce PAPR ofoptical OFDM system.From output constellation figure,it can conclude that the methodimproves the signal quality,solves the disorder of QAM constellation and extend thetransmission distance.In a word,compared with the traditional optical communication technology,O-OFDM reduced the complexity of dispersion management and improved spectrumefficiency. The theoretical analysis and simulation results can show that O-OFDM systemhas obvious advantages and research value. Particularly,O-OFDM has the very goodapplication prospects for ultra long haul and the high speed optical fiber communications.