Research On Beamforming Method In Multicell 3D MIMO System

As one of the key technologies in the fifth generation mobile communication systems,3D MIMO has received more and more attention.Compared with the traditional MIMO technology,3D MIMO can make full use of the vertical dimension of space freedom,which is conducive to improve the transmission performance of wireless communication system,and can further reduce inter-cell interference and improve the spectral efficiency.At present,the research on multicell 3D MIMO system is still relatively small,and the inter-cell interference problem is a difficult problem to be solved.The multicell joint transmission technology and 3D beamforming technology are applied to 3D MIMO systems,and the inter-cell interference is eliminated by the collaboration among the base stations,thus improving the spectral efficiency and energy efficiency of the system.This paper first introduces the 3D MIMO system and its channel model,and then aiming at the problem of inter-cell interference,the 3D MIMO joint transmission technology is introduced.By researching the downlink 3D MIMO system,adopting the zero-forcing(ZF)beamforming algorithm and combining with the multicell joint transmission scheme,analyze the influences of the base station antenna down tilt,the distance between the user and the base station,the number of users for the system transmission rate.Simulation results show that the multicell joint transmission compared to the single-cell transmission has better performance in increasing the throughput of the system.Secondly,considering the large amount of information interaction in 3D MIMO system,how to allocate the limited number of feedback bits in the horizontal and vertical dimensions is established,the optimization model is established to minimize SINR difference between the limited feedback and the ideal feedback.Combined with the analysis of the horizontal dimension and the vertical dimension of the channel gain ratio,the optimal bit allocation result is given under the condition of specific antenna configuration and the fixed feedback bits.Finally,under the 3D MIMO system simulation environment,due to multicell coordination scenario,the 3D beamforming technology is used to improve the power of the useful signal received by the users.In addition,by adopting the energy-efficient power control method effectively control inter-cell interference and improve the system energy efficiency.Simulation results show that the energy-efficient power control scheme based on 3D beamforming method has great advantages in improving the performance of the system.