Study On Massive MIMO Systems With Mutual Coupling

In recent years,the global information and communication industry is moving to the direction of mobile,broadband and intelligence.The development of the global In-ternet is about to enter the "industrial Internet era",which is foll integration of tradition-al industries and the latest information technologies such as cloud computing,big data,mobile Internet,Internet of things.With the rapid development of the Internet and the popularity of intelligent terminals,the demand for mobile data has reached an unprece-dented level and serious shortage of spectrum resources.In order to meet the great chal-lenge of the future mobile communication system to the spectrum efficiency and energy efficiency,the research of the fifth generation mobile communication system(The fifth mobile communication system,5G)has taken off.Massive MIMO technology can ef-fectively improve the spectral efficiency and significantly reduce the transmission pow-er,making it become the key technology of 5G.Massive MIMO technology requires that the number of antennas in the antenna array is up to tens to hundreds of times,so that the distance between antennas is small.At this time,we have to consider the mutual coupling effects on massive MIMO system.Firstly,the thesis analyzes the influence of mutual coupling on ergodic capacity and spatial correlation of traditional MIMO system.The simulation results show that the mutual coupling can reduce the spatial correlation of the traditional MIMO system,thus increasing the ergodic capacity of the MIMO system;The arrangement of antenna array has a great influence on the coupling effect.Then it analyzes the effect of mutual cou-pling on the achievable rate of massive MIMO system.In this thesis the EMF method for calculating the coupling matrix of antennas is introduced in detail,especially for the study of three kinds of antenna arrays including uniform linear array,uniform circular array and rectangular array.The simulation results show that the mutual coupling can reduce the achievable rate of large scale MIMO system.This thesis focuses on the effect of mutual coupling on the achievable rate of massive MIMO system when the physical size of the antenna array is limited,which gives rise to one contradiciting pheonment,that is,the increasing transmit diversity or receive diversity is due to increasing the number of antenna,but the adverse effect of mutual coupling on the achievable rate of massive MIMO system is increasing due to the decrease of the distance between the an-tennas,which requires a balance between the number of antennas and the distance among the antennas.The simulation results show that because of the effect of mutual coupling and spatial correlation,while the physical size of the antenna array is limited,the achievable rate of the massive MIMO system will not increase with the increase of the number of antennas,but the maximum value will appear.It is of great significance to find the maximum value by simulation analysis or mathematical calculation.