| With the continuous development of emerging technologies and services such as 5G,artificial intelligence,and big data,global Internet traffic has exploded.As a modern communication backbone network,the optical transmission network is facing increasing pressure on the transmission channel capacity,and the demand for large-capacity and long-distance optical fiber transmission systems is increasing.Nowadays,PM-QPSK and PM-16QAM are mainly used in commercial single-wave 100G and 400G optical fiber transmission networks.For single-wave 800G or T bits,higher-order modulation formats such as 64QAM are required to increase spectrum efficiency,but the transmission distance will be limited.Therefore,in order to solve the contradiction between transmission distance and transmission capacity,multi-dimensional modulation technology is proposed.By introducing multiple degrees of freedom(such as polarization,time domain,orthogonal mode,wavelength,etc.)to jointly modulate the signal,construct a multi-dimensional constellation to maximize the minimum Euclidean distance between signal points,and optimize the relationship between spectrum efficiency and asymptotic power efficiency.In the future,optical communication systems will tend to combine multiple transmission rates and multiple modulation formats.The recognition technology of modulation formats has received more and more attention in the field of optical communications.As a new type of optical modulation technology,multi-dimensional modulation format needs further research in modulation format recognition.This article mainly focuses on the research about the new multi-dimensional modulation format and recognition of multi-dimensional modulation format.A new multi-dimensional modulation format based on subset switch is proposed,and it is applied in 8PSK,16QAM,and multi-dimensional trellis coding modulation.As for modulation format recognition,a multi-dimensional modulation recognition method combining stokes space mapping and clustering algorithm is proposed,and a recognition method for multi-dimensional diversity modulation format is mainly carried out.This article mainly carried out the following works:This article mainly focuses on the research on the new multi-dimensional modulation format and the recognition of the multi-dimensional modulation format.The following work is mainly carried out:(1)A multi-dimensional modulation method based on subset switch is proposed.This method continuously transmits multiple subset points of the same type in the signal coding and modulation process,so that the minimum Euclidean distance between signal subsets is increased,and the asymptotic power efficiency is improved.The simulation results show that the transmission performance of 8PSK and 16QAM is obviously improved after using the subset switch modulation,and the coding gain of 3?6dB is obtained.In addition,the combination of subset switch modulation and multi-dimensional trellis coding modulation is used to simulate the transmission performance of 6D-TCM-8PSK signals based on subset switch modulation.The results show that compared with the unused subset switch modulation format,this method achieves 1.8dB coding gain.(2)Through a modulation format identification method combining stokes space with subtractive clustering,three common two-dimensional modulation formats QPSK,8PSK,16QAM and two multi-dimensional modulation formats PS-QPSK and 6Pol-QPSK are recognized.The simulation results show that under the condition of a signal-to-noise ratio greater than the corresponding threshold of the FEC correction error rate,the recognition accuracy can reach 100%.(3)A recognition method for multi-dimensional modulation format with set-partitioning is proposed.This method recognizes the multi-dimensional signal of the known basic constellation,and obtains its subset number by mapping the signal point to the position on the constellation.The characteristic value of the corresponding multi-dimensional modulation format with set-partitioning is extracted from the arrangement rule of the subset numbers in a group of signal points,which realizes the recognition of multi-dimensional SP-QAM and multi-dimensional TCM modulation formats. |
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