Research On Joint Power Optimization Of LDPC Coding And MIMO Precoding In 5G

The 5G cellular communication system can provide people with a high-speed,lowlatency,and reliable Internet experience.One of the key physical technologies of 5G is channel coding.LDPC(Low Density Parity Check)codes have been used in the e MBB(Enhanced Mobile Broadband)scenario in 5G standard with excellent performance and rate-matching compatibility feature.Another key technology is MIMO(Multiple Input Multiple Output)technology in 5G standard.MIMO can effectively guarantee the high-speed transmission of data and increase the channel capacity of the system without using additional bandwidth.The thesis studies the power optimization of LDPC codes with precoding of MIMO technology.Based on the Gaussian approximation method,we derive the power optimization model of LDPC codes with MIMO precoding.We also study the application of the proposed method in the PDSCH(Physical Downlink Shared Channel)channel of5 G,including the performance reduction introduced by imperfect channel state information.Finally,the simulation results show that the proposed power optimization method can bring good performance gains.The content of this thesis mainly includes the following five parts:The first chapter of this thesis introduces the related research background and the history of the related technologies including the development history of LDPC codes.Secondly,the MIMO technology and precoding technology are introduced accordingly.Finally,we give the significance and difficulty of the study on power optimization of LDPC codes combined with MIMO technology.In chapter 2,the research of LDPC code and precoding technology under MIMO are introduced in detail.Firstly,the structural features of LDPC codes are described.The related encoding algorithms and decoding algorithms of LDPC codes are introduced in detail,and the LDPC codes in the 5G standard are specifically described.Then the Gaussian approximation method for LDPC performance analysis is introduced.Finally,several traditional precoding techniques of MIMO are introduced.Chapter 3 firstly proposes an equivalent channel model based on precoding.Then we derive a LDPC Gaussian approximation model based on MIMO precoding technology.We give an analytical solution for power optimization under Gaussian approximation by minimizing transmission power.Finally,it is verified numerically that the proposed power optimization method can bring excellent performance gains.Chapter 4 firstly gives a brief introduction of the PDSCH channel of the 5G system.Secondly,we extend the results in Chapter 3 to more general scenarios,which are with high-order modulation and rate matching technology.We obtain the similar expressions of the power optimization for the two scenarios.Next,we consider the influence of the imperfect channel state information to the proposed method.Based on a large number of numeric analysis,we conclude that the proposed power optimization method can give significant performance gains even in these practical channel scenarios.Finally,in the fifth chapter,we summarize the study results and give the future research interests.