Research On 3D MIMO Beamforming Technology Based On Inter-cell Interference

Inter-Cell Interference(ICI)impairs system spectrum efficiency and restricts the improvement of performance of wireless communication systems.The 3D beamforming technology can effectively utilize the channel state information of the three-dimensional channel and precisely control the beam state in the vertical dimension,thereby effectively improving user signal strength and suppressing inter-cell interference.In this thesis,the 3D Massive MIMO system is established.With the aid of 3D beamforming technology,the strategy of interference cooperative beamforming based on spectrum efficiency and the scheme of efficient beamforming based on power control are proposed for the inter-cell interference problem.In addition,we verified the proposed algorithm through the simulation.The main contents and innovations of this thesis are as follows:(1)Aiming at the characteristics of 3D Massive MIMO system under imperfect channel,this thesis proposes an interference cooperative beamforming scheme based on spectral efficiency in order to further improve the system throughput.In this scheme,a modified greedy downtilt search algorithm is designed.The proposed algorithm deploys the adaptive optimal downtilt for the base station while reducing the complexity.In order to further reduce the inter-cell interference level,a distributed partial cooperative downtilt regulation strategy is proposed,which limits the effect of the primary interfering base station on the neighboring cells and ensures the rate of users who are at the edge of the cell.Simulation results show that the proposed algorithm can effectively reduce the inter-cell interference and improve the system throughput.(2)Based on the goal of optimizing the energy efficiency of the system,this thesis proposes a joint scheme of efficient power control from the perspective of power control.In this scheme,the idea of distributed algorithm is used to decouple the multi-dimensional optimization objectives into two steps:the first step is to fix the base station transmission power.To ensure system spectral efficiency,the modified greedy downtilt search algorithm and the distributed partial cooperation strategy are also used to deploy the adaptive optimal downtilt of the base station.Based on the optimal spectral efficiency,in order to further improve the system energy efficiency,an adaptive optimal transmission power is set for the base station by designing the improved stochastic ranking evolution strategy and part of cooperation transmission power regulation strategy in the second step.While reducing the complexity,the joint optimization of system spectrum efficiency and energy efficiency is realized.Finally,the simulation proves the effectiveness of the scheme.