Channel Modeling Of 3D Dynamic Multi-link MMIMO In High-Speed Railway Scenarios

With the continuous renewal and integration of science and technology,the future high-speed railway will tend to be intelligent,that is,intelligent high-speed railway will become one of the important development directions of high-speed railway in the future.Therefore,the world has invested a lot of manpower and material resources to carry out a series of scientific research on intelligent high-speed railway.However,the mobile communication system of intelligent high-speed railway combines a new network architecture and a new generation of information technology,so before designing the system,we need to accurately recognize the relevant characteristics of high-speed railway wireless channel.The research methods of channel characteristics are extensive and have their advantages and disadvantages,and the channel theory modeling method is favored by researchers because of its advantages of good universality and high accuracy.Based on the multi-link dynamic channel in high-speed railway scenario,this paper establishes a suitable theoretical model and carries out research and analysis work.The main contents of this paper are as follows:Firstly,based on the theory of geometry based stochastic model and the actual communication scene of high-speed multi-link railway,the common scatterer is modeled as a single sphere model,and the uncommon scatterer is modeled as an elliptical cylinder model with common focus.Two adjacent base stations and the mobile relay station are located at focus of the elliptical cylinder and spherical center,respectively.According to this model,two typical features of mMIMO technology are considered: spherical wave assumption and dynamic evolution of clusters.The key characteristic parameters,spatial cross-correlation function,time auto-correlation function and sum rate capacity of multi-link channel are deduced.In addition,the corresponding simulation model is established based on the method of equal volume,and the influence of each parameter on channel characteristics is analyzed comprehensively.In addition,the GBSM theoretical model is verified by using the actual measurement results in high-speed railway scene.The results show that the 3D theoretical models have certain accuracy.Combined with the current beamforming technology and the narrow beam medium and high frequency band technology,the theoretical model is optimized and adjusted again,and the 3D mMIMO dynamic narrow beam channel model of multi-link is established in the high-speed railway scene.This model introduces the concept of "beamwidth dependence" in the form of directional antenna,and considers the dynamic evolution characteristics of clusters in frequency domain.At the same time,the channel characteristic parameters are enriched,and the channel auto-correlation function,frequency correlation function and spatial cross-correlation function are derived and simulated.