Research And Implementation Oriented 3D MIMO Interference Suppression Schemes For 5G

Three dimensional multiple input multiple output(3D MIMO)technology makes full use of the horizontal and vertical dimension antenna degrees of freedom,which can better suppress the interference in the system and effectively improve the system capacity.It has become the core technology of 5G mobile communication.In order to further improve the sum rate of 3D MIMO system and reduce the interference in the system,this dissertation studies the interference suppression technology of 3D MIMO system,and mainly studies precoding schemes of 3D MIMO system.The main work is as follows:Firstly,this dissertation proposes a multi-layer precoding scheme based on user grouping for the interference suppression problem in 3D MIMO downlink cellular systems using only Channel State Information(CSI).Based on a lower bound of the average signal-to-leakage-plus-noise ratio and taking the fairness of scheduled users into account,we propose a user grouping algorithm exploiting only statistical CSI.Then we apply the user grouping algorithm to the multi-layer precoding framework.The proposed scheme greatly reduces the CSI required by the BS with using only users' statistical CSI.Simulation results show that the proposed scheme can achieve good fairness and high sum rate.Secondly,this dissertation studies the feasibility of the downlink transmission mode in 3D MIMO systems for two types of users,the users with only statistical CSI and the users with instantaneous CSI.The design problem of downlink precoding for mixed utilization statistics and instantaneous CSI is solved.Using the properties of the Kronecker product of the 3D MIMO channel,an extended zero-forcing precoding method is proposed to minimize the total transmit power of the BS.Simulation results show that the scheme has lower complexity and good rate.