Research On Adaptive Coding And Modulation In 5G

5G communication system has been commercially launched recently.It will provide high speed,low latency,low power-consumption and ultra-reliability communication services.Low Density Parity Check(LDPC)codes benefited in near-capacity performance and highly parallel computing have been the coding scheme for 5G Enhance Mobile Broad Band(eMBB)scenario.Multiple Input Multiple Output(MIMO)is a revolutionary technology since it can greatly bring the multiplex and diversity gains of wireless communication system.It has been another key technology of 5G system.The combination of various technologies in the wireless communication system often brings more challenges to signal processing and optimization.This thesis studies the joint optimization of LDPC coding and MIMO technology.We focus on the power optimization on the transmission of LDPC codes in MIMO system based on Gaussian approximation.The main research content is as follows.In the first chapter,we introduce the development of contemporary wireless communication and channel coding.Especially,we emphasize on the introduction of LDPC codes and MIMO technology in 5G.Finally,we list the research content of this thesis.In the second chapter,the theory of LDPC coding,density evolution and Gauss approximation are introduced,and the MIMO precoding technology is also introduced.Finally,we give an overview of the physical channel of Physical Downlink Shared Channel(PDSCH)in 5G NR.In the third chapter,we focus on the power optimization method of MIMO in 5G system and propose a power optimization method based on Gaussian approximation.Firstly,the transmission process of LDPC coding over MIMO system is mathematically modelled as the optimization problem based on Gaussian approximation theory.We finally give the closed-form solution of the optimization problem.Finally,we give a few simulations so as to verify the correction of the solution and exhibit the gain of the proposed scheme.In the fourth chapter,we focus on the study on the proposed method in 5G scenario.It will have some new challenges in applying the proposed power optimization in channel in 5G.It mainly involves in rate-matching and high-order modulation.We finally give a new solution of power allocation involved in the two aspects,respectively.Finally,some simulations are given to verify the validity of the proposed method.In the last chapter,we summarize the thesis and give some promising research interests.