Performance Of Nonlinear Frequency Division Multiplexed Path-averaged Solitons Transmission Systems

With the development of communication industry,and the wide application of high-definition video calls and cloud computing,network bandwidth requirements grow explosively.Therefore,we should improve the capacity of data communication as soon as possible.Coherent optical communication has attracted more and more attention for its high transmission rate and high sensitivity.However,fiber nonlinearity has become the limiting factor of optical communication capacity.Recently,people proposed a new transmission scheme named Nonlinear Frequency Division Multiplexing(NFDM),which is based on Nonlinear Fourier Transform(NFT).This scheme,which combines with the soliton theory,is found to be immue to fiber nonlinearity.It can potentially replace the traditional WDM system and improve the communication capacity.The traditional NFDM transmission system applies Raman amplifier,which results in strong nonlinearity.Therefore,we remove the Raman amplifier and propose a new method called path-averaged soliton to keep the same performance.Firstly,we briefly review the history of optical coherent communication,and the impact of fiber nonlinearity on optical communication capacity.Then,we proposed NFDM transmission system,and emphasize the importance of the scheme based on its advantages.In order to overcome the disadvantage of the traditional NFDM transmission system,we mention the necessity to improve the system.Secondly,the nonlinear Fourier transform is defined.We analyze the performance of receiver eigenvalues in traditional NFDM systems with Raman amplifier.Compared with the traditional scheme,we propose a new method named path-averaged soliton,which removes the Raman amplifier and improves the input signal power.Then we analyze the performance of receiver eigenvalues.We also study the relationship between bit error rate and sampling value with different algorithms of the NFT signal.Finally,simulations are performed to analyze the impact of frequency offset and laser phase noise on NFDM system.Simulation results show that the system is robust to both factors.Then,we modulate two eigenvalues in the improved system with QPSK.This generates two kinds of waveforms to detect.Meanwhile,we modulate one single eigenvalue in the phase modulation system,and analyze the impact of the signal power fluctuation and the line width.