Statistical Channel Model And Signal Space-time Characteristic Analysis In Multiple Scenarios

With the rise of the mobile Internet and the popularization of smart phones,the development of wireless communication technology has attracted more attention,and people have higher and higher requirements for the quality of mobile communications.As a key part of the communication system,wireless channel has always been one of the research focuses in the field of communication study.The wireless channel modeling technology is of great significance to improve the resource utilization of communication system,reduce the signal attenuation and optimize the performance of communication system.This paper mainly studies the channel fading characteristics of wireless communication systems,and builds geometric channel models for different physical scenarios.We analyze the wireless signals' statistical distribution characteristics of the angle of arrival(AOA)and the time of arrival(TOA)under different propagation scenarios,and derive the joint probability density function(PDF)of angle and delay of simultaneous interpreting and correlation of multiple antenna arrays under massive multiple input multiple output(Massive MIMO)system and through the analysis and comparison of multiple sets of data to study the performance of the communication system.The specific work is divided into the following aspects:Firstly,this paper introduces the development and iteration of mobile communication technology,introduces the concept of channel modeling technology and channel fading in wireless communication system,analyzes the large-scale fading and small-scale fading in wireless channel in detail,and introduces the classic geometric ellipse model and circular model in fading channel,which lays the foundation for the establishment of channel model in multi scenes.Then,aiming at the suburban micro-cell scenes under rainfall environment,a single scattering statistical channel model based on elliptical geometry was established.In this model,trees distributed uniformly in suburbs are used as scatter to quantify the changes of signal transmission environment caused by rainfall effect;the transmitting end and receiving end of the communication system are respectively set in the focus of the elliptical scattering area.With the help of the symmetry of the elliptical geometry model,the probability density distribution of TOA and AOA and the change of joint PDF of the propagation signal under different parameter environment are analyzed,and the influence of rainfall on the signal fading is studied.Based on the channel fading characteristics of the single-scattering system,we further study the angle and delay distribution of the arrival signal in the channel model after secondary scattering.The simulation comparison between the single scattering model and the second scattering model confirms the power attenuation effect of rainfall on the propagation signal,and with the increase of the number of scattering,the arrival delay of the signal will obviously increase,this result is helpful for further analysis of the performance of the communication system under the fading channel.Finally,for a massive MIMO system with multiple antenna arrays,a three-dimensional geometric channel model with a uniform linear antenna array(ULA)at the base station is established,and the near-field effect and far-field effect are considered separately according to the distance between the signal source and the base station antenna.The spherical wave(SW)model and the plane wave(PW)model are introduced to simulate the multi-antenna transmission of wireless signals at different distances.The validity of the channel model is verified by analyzing the average correlation of the signals of multiple antenna systems and the channel capacity in different situations.The simulation results show that the near-field effect contributes to the antenna decorrelation of massive MIMO systems,thereby improving the signal transmission stability and channel capacity of multi-antenna systems.The research results help to further analyze the signal transmission characteristics of massive MIMO systems with complex antenna arrays.