Research On Key Technologies In Multi-band Fiber Transmission System

With the vigorous development of 4K video,virtual reality,artificial intelligence and other emerging technologies,the network traffic is growing rapidly,which puts forward higher requirements for the bandwidth and capacity of the communication system.As the main transmission medium of the current communication system,optical fiber communication is also developing towards the direction of large capacity and long distance.At present,single-mode optical fiber communication mainly uses C+L-band,and its transmission capacity has approached the Shannon limit,which can not support the future traffic growth.Multi-band fiber transmission extends the commonly used C+L-band to O to L-band,which can use the existing laid optical fiber to multiply the communication capacity.Therefore,it is of great significance to study the key technologies in multi-band fiber transmission system.This paper studies the key technologies in multi-band fiber transmission system.Firstly,the theoretical model of multi-band fiber transmission system is established,and the influencing factors of optical communication are analyzed.Then,the adaptive coding and modulation method of multi-band fiber transmission system is proposed,and the channel equalization algorithm in multi-band fiber transmission system is explored and studied.The main research work is as follows:(1)The theoretical model of multi-band fiber transmission system is established.Optical signal transmission in optical fiber will be affected by attenuation,dispersion and nonlinearity,and the channel parameters in different bands are different,resulting in different signal distortion;Raman effect will transfer the power of short wavelength to long wavelength,resulting in the power tilt of the spectrum of the whole multi-band system.The transmission models of different bands are established by solving the nonlinear Schrodinger equation.The Runge Kutta method is used to solve the ordinary differential equation of Raman response,and then the influence of Raman effect on the whole band is studied.The simulation results show that in the multi-band fiber transmission system,the BER of O-band is the worst,the transmission performance of C+L-band is better,and there will be large power transfer between S-band and L-band due to Raman effect.(2)An adaptive coding modulation method in multi-band fiber transmission system is proposed.In multi-band fiber multi-carrier transmission system,the difference of damage factors leads to the difference of transmission performance of different channels.In order to alleviate the problem of unbalanced signal transmission,this paper carries out adaptive coding and modulation for different channels,and compares different bit power allocation algorithms.The simulation results show that when the spectral efficiency of the whole system remains unchanged,compared with the traditional design the designed adaptive coding and modulation method will have a SNR gain of 5 dB in O-band and E-band and 2 dB in S-band.(3)The channel equalization algorithm of multi-band fiber multicarrier transmission system is studied,and the MMSE algorithm based on K-means and SVD is proposed.Simulation results show that the proposed algorithm has a SNR gain of 0.5 dB compared with the MMSE algorithm based on SVD.