Research On Modulation Format Identification Technology Of Intelligent Optical Network Physical Layer

Unlike the modulation recognition technology in the wireless communication network,the development technology is relatively mature.Although the modulation recognition technology in the field of optical fiber communication has just started,it causes more and more attention due to its potential research value and great application prospects.In order to analyze the intelligent optical network physical layer optical transmission system in theory,the networking scheme of ASON + DWDM is adopted in this paper,and uncompensated optical transmission system(UT)model based on dense wavelength division multiplexing(DWDM),and the derivation of the model is discussed in detail.The study of the pattern recognition algorithm based on the DWDM-UT system model in this paper.The study involves four types of 18 kinds of modulation signals,namely,the amplitude modulation signal(MASK),the phase modulation signal(MPSK),the phase and amplitude modulation signal(MQAM and MAPSK).The modulation format identification(MFI)proposed in this paper is based on the eigenvalue parameters of the high order cumulant(HOC)of the modulated signal,and the classification decision algorithm is used to classify the different modulation signals.Based on the thresholds used in the classification decision algorithm,taking into account the fact that the eigenvalue parameters of different modulation signals change with the change of signal-to-noise ratio,a real-time training sequence threshold optimization(RTTSTO)algorithm is proposed creatively.It is found that the algorithm can effectively guarantee the accuracy of the threshold and greatly improves the recognition effect of different modulation signals.Considering the influence of dispersion(D),nonlinear effect(?)and transmission distance(L_tot)on the DWDM-UT system of intelligent optical network,we study the influence of these factors on the performance of format identification,and the tool matlab gives the corresponding simulation results.At the same time,in order to further verify the validity of the proposed MFI algorithm,we have also discussed the high-speed Nyquist WDM based on PM-QPSK modulation which has been widely put into use.By VPI and Matlab,the results show that the system even after ultra-long distance transmission,modulation signal recognition rate of PM-QPSK can reach 96.5% or more.These results provide a theoretical basis for the future implementation of intelligent optical network physical link.