Massive MIMO Channel Modeling And Ayalysis Using Ray-tracing

With the rapid popularization of intelligent terminals,the demand for mobile data services has reached an unprecedented level,which leads to the scarcity of frequency spectrum resources and the requirement of improving the spectrum efficiency.Large-scale MIMO(multiple-input multiple-output),with giant array size and multi-dimension array structure,has been widely considered as a key physical layer technique in future wireless communications.At present,the researches of large-scale MIMO mainly focus on the high frequency transmission,the three-dimensional beamforming,the high efficiency precoding and the diversity technology.Using the accurate channel model,the above techniques can significantly improve the spectral efficiency.However,some new challenges are arising,e.g.modeling the near-field effects in MIMO channel and the high computational complexity,due to the large number of antennas.To solve these issues,the channel modeling for large-scale MIMO is thoroughly studied in this thesis.The details are as follows.Firstly,we established the framework of large-scale MIMO channel model.Compared with the traditional linear array MIMO,the electromagnetic propagation in large scale MIMO becomes more complex,because the large scale MIMO uses the multi-dimensional array structure,and the spatial resolution is extended from two-dimension(2D)to three-dimension(3D).By researching the electromagnetic wave propagation in three-dimensional space,including the map projection between antenna space and communication space,and the polarization rotation of the electromagnetic wave in the three-dimensional space,the framework of large scale MIMO channel model is proposed based on the clustered delay line.Secondly,the map-based ray tracing algorithm are implemented in this work.The aims of map-based ray tracing algorithm were to establish an accurate and practical spatial channel model,which can support some applications in future communication system,such as large scale MIMO,advanced beamforming,node movement and high bandwidth.In this work,the ray tracing algorithm based on a simplified 3D map is implemented using Matlab.With the consideration of the electromagnetic propagation characteristics of reflection,scattering,diffraction and transmission,the computational complexity of implemented algorithm can be adjusted by opening or closing the different paths.The statistical distribution of the parameters of the large scale MIMO channel model are solved using the ray tracing algorithm.For the large scale MIMO,the statistical distribution of antenna elements at different location are not the same,because their visual ranges are different.In this part,the statistical distributions of path loss,delay spread and distance between antenna element and scatters are solved using map-based ray tracing algorithm.