Study Of High-Dimensional Modulation Mapping Technology Based On Subset Selection

In recent years,with the rapid development of the Internet industry,emerging technologies such as cloud computing and big data have been popularized,and many high-capacity data services such as high-definition video,cloud storage,and live video are increasing.Such a fast-growing traffic demand brings huge traffic carrying pressure to the optical transport network.In order to alleviate the pressure,the optical transmission network will be developed in the direction of ultra-high speed and large capacity.Then,one of the main problems that the current fiber-optic communication system faced with is how to upgrade the present transmission network without additional trunk line rebuilding cost.Utilizing high-order modulation formats is one of the most effective means of capacity enlargement.However,the spectral efficiency and the power efficiency is a pair of contradiction.For higher order modulation formats,the spectrum efficiency is high,but the power efficiency is reduced.Under the same transmission power and target bit error rate,the smaller power efficiency will result in a shorter transmission distance.To solve this problem,the high-dimensional modulation formats are coming.The high-dimensional modulation can be used to modulation data simultaneously by using the orthogonal state,polarization state,time slot,frequency and other degrees of freedom in the optical field.Increased degrees of freedom can increase the asymptotic power efficiency of the signal by maximizing the minimum European distance between constellation points.It can also reduce the probability of misjudgment at the receiver by maximizing the minimum Euclidean distance between constellation points,so as to obtain the better transmission performance.The proposed high-dimensional modulation format can better solve the contradiction between the spectral efficiency and the asymptotic power efficiency of the conventional two-dimensional modulation format,and achieve a smooth upgrade of the transmission capacity of the optical communication system.As a novel modulation format,high-dimensional modulation format still has many problems to be solved,one of its key technology is high-dimensional modulation mapping technology.High dimensional modulation mapping technology is to solve the problem that how to select high dimensional constellation set and how to quickly find the relationship between bits and constellation points.However,the spatial distribution of high-dimensional points is complex and the scale of constellation set is huge,which leads to the difficulty in the implementation of themapping process.In this paper,the high-dimensional mapping is studied in depth,focusing on solving the two problems of high-dimensional modulation mapping technology,and a high-dimensional modulation mapping technology based on subset selection is proposed.The paper content is arranged as follows:Firstly,the research purposes and research results of high-dimensional modulation rate-adaptive technology are reviewed.Based on the development of high-dimensional modulation format at home and abroad,this paper introduces the research results obtained in this field,points out the significance of studying high-dimensional modulation format and its key technologies,and analysis the advantages of adopting high-dimensional modulation format.Then,we explained the basic concepts and major parameters of highdimensional modulation formats,especially for implementation methods of high-dimensional modulation signal,asymptotic power efficiency and spectral efficiency.This paper summarizes and analyzes several typical high-dimensional modulation formats from the aspects of realization principle,mapping method and performance.In addition,we also analyze and summarize the key technologies of high dimensional modulation format.Secondly,how to select the high dimensional constellation set is the first problem to be solved for Subset Selection mapping technology.In order to solve the problem,a new method of high dimensional constellation design based on extensional set-partition is proposed.Beginning from the importance of selecting the constellation set based on Subset Selection mapping,the necessity of selecting the optimal geometric distribution constellation point set is explained in detail.At the same time,the implementation principle and steps of the high-dimensional constellation set based on the extensional set-partition method are given,and compared with the two-dimensional constellation in terms of asymptotic power efficiency,spectral efficiency and SER performance.Then we get the performance advantage of the high dimensional constellation based on the extensional set-partition method.Thirdly,on the premise of solving constellation set selection,a high-dimensional modulation mapping technology based on Subset Selection is proposed to solve the problem of the relation between bit and constellation point set.Based on the basic theory of high-dimensional mapping,the realization principle of Subset Select mapping is expounded.The flow chart of the mapping and de-mapping method is given.The derivation process of the mapping formula is given,which simplifies the realization process of high-dimensional mapping,and lays a solid theoretical foundation for the realization of high dimensional modulation format.Finally,we build a simulation system of high-dimensional modulation format,and verify the high-dimensional modulation mapping performance based on Subset Selection mapping by simulation experiment.The receiver complexity and BER performance of four and eight dimensional modulation formats are analyzed,which proved the good performance of the high-dimensional modulation mapping based on the Subset Section.