Research On Geometric-based Massive MIMO Channel Models And Characteristics

With the rapid growth of the number of mobile network terminals,as well as the development of intelligent applications,cellular networks face the demand for higher user density and higher data rates.Massive MIMO technology is one of the most effective ways to solve this realistic problem.Due to the significant improvement of antenna array dimension of massive MIMO system,it shows some unique channel characteristics compared with traditional MIMO systems.Therefore,it is very important to establish an efficient and accurate massive MIMO channel model for its popularization and application in wireless communication system.The thesis mainly studies the geometric-based stochastic channel model for massive MIMO systems.A novel three-dimensional multi-confocal ellipsoid channel model is established.At the same time,this thesis studies the engineering simulation of channel model in depth.A geometric-based stochastic channel model simulation platform is established,and a common statistical channel model verification method is proposed.The main work and innovation points of this thesis are summarized as follows:1)In the study of massive MIMO channel modeling theory,a new geometry-based three-dimensional multi confocal ellipsoid channel model is proposed.The transmission environment in which isotropic scatterers and non isotropic scatterers coexist is considered in the model,which ensure the model more widely used.Under the assumption of spherical waveform,the mathematical relationship between the angle of arrival(AOA)and the angle of departure(AOD)in the ellipse based model is derived.This not only makes the model more accurate,but also can be used to simulate the non-stationary characteristics of the channel.The model studies the non-stationary characteristics of the scatterer cluster in the antenna array dimension in massive MIMO system,and uses the idea of renewal process to model it.Compared with the classical birth and death process method,the computational complexity is lower.The validity of the proposed model is verified by comparing with the classical channel model.The influence of various channel parameters on channel correlation is analyzed,including time correlation,spatial correlation and frequency correlation.2)In the engineering simulation of channel model,a general channel model verification system is designed.This thesis presents a method to verify the channel model by using the statistical characteristics of channel amplitude.Compared with the existing methods which only aim at specific channel model,this method can be applied to almost all statistical channel models;on the other hand,a simulation platform based on geometry-based stochastic channel model is established.The platform obtains the channel impulse response by setting the relevant channel parameters,and provides the visualization function of the transmission environment.It is helpful to deduce the geometric relationship of the geometry-based stochastic channel models,and improves the efficiency of the link level simulation of the channel model.