Research On Channel Equalization And Compensation Algorithm In Optical Communication System

The combination of digital signal processing(DSP)technology and coherent receiving technology can effectively realize the channel equalization of the electric domain and the huge demand for information transmission capacity can provide reliable guarantee for super-fast and large-capacity information system.So it is widely used in optical fiber communication.In dynamic optical network,the equalizer and equalization algorithm used in receiving end dispersion equalization becomes the key of the channel equalization.Since the performance of the transmission link is subject to the influence of various factors in the environment,the chromaticity dispersion(hereinafter referred to as dispersion)in the link is easily affected by the environmental impact.Thus,after we compensate dispersion in the transmission link by means of static dispersion compensation,it is still necessary to take the dynamic adaptive algorithm to effectively treat the redundant dispersion in order to achieve the final desired signal transmission quality.In this paper,compensation algorithms of dispersion in coherent communication system are studied.The main contents are as follows:(1)This paper use MATLAB software to build a simulation platform of 25GBaud QPSK and 16QAM coherent communication system to realize the generation,transmission,reception and recovery of signals.(2)The dynamic dispersion compensation algorithm based on the constant mode algorithm(CMA)was completed and the dispersion compensation performance and complexity analysis of the 25GBaud QPSK and 16QAM systems were performed.The results showed that under the light signal noise ratio of 6dB,8dB and 10dB,the compensation range of QPSK are ± 160ps/nm,± 640ps/nm and ± 1280ps/nm.Under the optical signal-to-noise ratio of 15dB,17dB,25dB,the compensation range of 16QAM are 0,±450ps/nm,±880ps/nm.In addition,the computational complexity of CMA was analyzed.Concluded in this paper,there was a positive correlation between the computational complexity of CMA and 2 times of tap length.(3)It is proposed an adaptive dynamic algorithm based on the time error analysis.And we realize the simulation of the dispersion compensation performance and complexity analysis of 25GBaud QPSK and 16QAM system,the analysis results show that under the light signal noise ratio of 6dB,8dB and 10dB,all of the compensation ranges of QPSK are ±320ps/nm.Under the light signal noise ratio of 15dB,17dB and 25dB,all of the compensation ranges of QPSK are ±320ps/nm.The simulation results verify that the algorithm is insensitive to the modulation format of the signal.And the computational complexity of the algorithm is calculated.It is proved that there was a positive correlation between the computational complexity of the proposed algorithm and logarithmic of the FFT block size.