Research On Transmission Performance Of GFDM Based On Signal Shaping In High-Speed Optical Communication System

Online education,real-time video and other applications and various types of network equipment are appear frequently,and the demand for IP is rising.The higher and higher requirements accelerate the development of various signal processing technologies and channel processing technologies in high-speed optical communication.How to control or even reduce the possibility of signal error while improving communication capacity is an urgent research topic at present and for a long time in the future.Compared with orthogonal frequency division multiplexing(OFDM)in 4G,generalized frequency division multiplexing(GFDM)in 5G has the advantages of lower Out-of-Band leakage,which makes it a key candidate technology for communication development,but its anti-interference ability and signal transmission accuracy need to be improved.This thesis studies the key principles of GFDM modulation and demodulation signals.On this basis,in order to reduce the bit error rate and improve the generalized mutual information,the GFDM scheme based on PS and LDPC coding modulation,the GFDM scheme based on signal pair optimization and shaping,and the signal clustering scheme for fiber receiving GFDM and PS-GFDM are emphatically studied.The main innovations and work contents of this thesis are as follows:(1)A generalized frequency division multiplexing scheme based on PS and LDPC coding is proposed.In this scheme,the signal is PS and a novel 16QAM symbol mapping scheme is designed.Furthermore,the signal modulated by GFDM is preprocessed by LDPC coding.It solves the problem of low bit error performance caused by non-orthogonality of GFDM technology.The transmission performance under different optical signal-to-noise ratios(osnrs)in the optical communication system is simulated and researched.The results show that the proposed scheme has advantages in anti-interference ability and power.Compared with the traditional GFDM scheme,the proposed scheme can save about 3dB/(rad/sample)of power.When the transmission distance is 40km,the signal-to-noise ratio gain is as high as about 4.97dB at the bit error rate of 3.8 ×10-3.(2)A generalized frequency division multiplexing scheme based on parity optical-probablistic shaping(POPS)is proposed.This scheme optimizes the GFDM modulation scheme by studying the pairwise optimization algorithm for PS signals,which solves the performance limitation of the traditional fixed square QAM constellation on GFDM modulation signals and reduces the OOB radiation of GFDM to a certain extent.The performance of coherent optical communication under different transmission distances and different signal-to-noise ratios is simulated.The results show that the OOB leakage of the proposed POPS-GFDM scheme is reduced by about 4dBm compared with the original scheme,The transmission distance of the proposed scheme is increased by 75km compared with the traditional GFDM scheme when the GMI value is 3.2bits/symbol.(3)A clustering scheme based on GFDM and PS-GFDM signals at the receiving end of optical fiber transmission is proposed.In this scheme,the clustering performance of K-means and GMM algorithms is researched,and a clustering scheme is proposed to optimize the starting point of PS signal,and to cluster GFDM signal and PS-GFDM signal at fiber receiving end.In a way,it resists the bit error rate problem of signal nonlinearity caused by optical fiber Kerr effect.The BER performance under different fiber input powers is simulated,compared to the GFDM without clustering,the BER performance of the other two schemes which are the uniform GFDM scheme and PS-GFDM scheme with receiving clustering is better.PS-GFDM has better performance than ordinary clustering when using starting point optimization clustering.