Research On 3D MIMO Channel Characteristics And Modeling For 5G

3D MIMO technology can utilize horizontal and vertical dimensions at the same time,greatly improves the system capacity,which is one of the key technologies in 5G.The conventional 2D MIMO channel model assumes that the wave propagates in the azimuth plane,which is not suitable for evaluating the performance of 3D MIMO technology.In order to deeply research and use 3D MIMO technology,it is necessary to build 3D MIMO channel model.The main work of this paper is as follows:First of all,a 2D MIMO channel model is extended to 3D on the basis of WINNER II by introducing the elevation angle.And the correlation matrices of two link ends are respectively derived in this paper.A 3D Weichselberger model is constructed through the eigenvalues decomposition of correlation matrices at two link ends respectively.And compared with 3D Kronecker channel model,the simulation results also show that the 3D Weichselberger channel model is more close to 3D MIMO channel characteristics and can reflect the propagation performance of MIMO system more accurately.Secondly,the spatial coupling matrix of 3D Weichselberger channel model and its relationship with system propagation scenario and channel capacity are studied.The spatial coupling matrices are analyzed in six typical scenarios and the characteristics of 3D MIMO channel in various scenarios are deduced.To achieve desirable tradeoff between performance and complexity,a novel spatial coupling matrix is proposed based on these typical structures.Furthermore,the upper bound of mutual information for 3D Weichselberger model is derived based on spatial coupling matrix which can be used in arbitrary propagation scenario.Thirdly,the influence of angle distribution on 3D MIMO system performance is analyzed through comparing Gaussion distribution,Laplacian distribution and VMF distribution.Simulation shows that VMF which can model elevation angle and azimuth angle jointly is most suitable to be used in 3D MIMO system.Furthermore,how the concentration parameter of VMF distribution reflects the distribution of scatterers is studied.Finally,the channel capacity of 3D single user and multi-user MIMO system is analyzed respectively.The dimension of the MIMO channel matrix will increase as the number of antennas increases.In order to reduce the computational complexity of the channel capacity,based on the Taylor series,the approximate channel capacity of the 3D single user MIMO system is derived,and then extended to the multi-user system.The simulation results show that the approximate expression can accurately calculate the channel capacity of 3D MIMO system in the low SNR region and the capacity of 3D multi-user MIMO system is higher than that of 3D single user MIMO system.