Research On MIMO Channel And Its Performance Based On Angle Domain Sampling

With the rapid development of 5G/6G in the world in recent years,the demand for anytime,anywhere,and efficient data transmission has made mobile communication scenarios diversified and complicated,resulting in multidimensional,asymmetry,and arbitrariness of wave-of-arrival signal spectrum.Therefore,the modeling and estimation of the channel becomes more complicated.Studies have proved that MIMO technology can make great use of existing space resources and multiple spatial dimensions,and can effectively combat the fading of wireless channels without increasing additional system bandwidth and radiation power,and further improve the system's spectrum utilization rate.In order to grasp the characteristics of the MIMO wireless channel in indoor and outdoor environments,it is necessary to measure the actual environment to establish a suitable channel model,predict the performance of the system and evaluate the pros and cons of the algorithm.This thesis focuses on the modeling of MIMO channels in two-dimensional and three-dimensional spatial domains.For any scattering environment channel,the power azimuth spectrum,spatial correlation,and angle expansion of the channel model are deduced and analyzed in depth and the impact on system performance.According to the relevant channel test results,the test environment and test results are used to optimize the parameter configuration to approach the actual channel and accurately model the channel.Firstly,it introduces the propagation characteristics of wireless fading channels and the principles and research status of MIMO channel modeling.Taking a uniformly distributed linear antenna array as a model,when the angular power spectrum of the incident signal is uniform,Gaussian,Laplacian,and Sinc distributions,the expressions of their respective spatial fading correlation functions are derived.Aiming at the problem of channel distribution uncertainty in the real environment,a MIMO promotion model suitable for non-uniform scattering environment is proposed based on the probability area division method of incident angle.Equivalently fitting large-angle expansion through small-angle expansion,using Sinc,Gaussian,and Laplacian distributions as sampling basis functions and reference standards,fitting to obtain an approximation of the spatial fading correlation function of MIMO multiantenna channel under arbitrary angle domain power spectrum Simplify the solution.Secondly,the DOA estimation technology is used to obtain the measured data in the urban microcellular environment,analyze and extract the characteristic parameters of the MIMO wireless channel,and perform exponential nonlinear regression fitting processing on the discrete data,and construct a MIMO channel model based on actual measurement.The approximate simplified solution of spatial fading correlation function under multiple basis function sampling models is derived,and the selection basis and fitting accuracy of the number of sampling basis functions and weighting coefficients in the simplified model are analyzed in detail.The fitting and simulation results of the measured data in the urban area show that the approximate fitting algorithm can meet the accuracy requirements of actual channel modeling while reducing the computational complexity.This shows that the proposed sampling fitting method can further improve the applicability of the approximate algorithm.Finally,for the multipath fading environment of the three-dimensional incident wave,a3 D MIMO system receiving model is established.First,the closed expression of the spatial fading correlation function is derived based on the angle power spectrum of the horizontal dimension and the vertical dimension,and the formula is simplified by using the MT transform.Then,the numerical simulation results are obtained by analyzing the influence of the model parameters on the performance of the 3D MIMO system.The research proves that the improved simple closed-form approximate expression is suitable for the incident wave with 3D environment diffusion.Finally,compared with several traditional classic models,the proposed method is simpler and more efficient,and provides a good foundation for further analysis and discussion of multipath channels in the future.