The Research And Implementation Of Interference Suppression Technology For 3D MIMO

Three Dimension Multiple Input Multiple Output(3D MIMO)has become key technology in 5G.Interference suppression,as a core technology in 3D MIMO,can adjust downtilt dynamically and improve system sum-rate and limit interference,which has attracted more and more interesting.In this paper,we focus on interference suppression and do some research.We focus on two technologies: beamforming and precoding.The work as follows:Firstly,we provide a scheme which can transform 3D beamforming into finding optimal antenna downtilt,specific to 3D multi-user MIMO Networks based on larger scale fading.First,we use Max Ratio Transmission(MRT)precoding.We assume desired signal power,inter-user interference power and inter-cell interference follow the Gamma distribution,then we can formulate an optimization to maximize system throughput in relation to antenna downtilt.Finally,we proposed an improved quantum bacterial foraging algorithm(QBFO)to find its solution.Simulation result shows that proposed scheme has higher achievable sum-rates in lower SNR and better performance using QBFO.Secondly,in time division duplexing(TDD)systems,the multiplexing of uplink training pilots among cells leads to channel estimation errors,which causes downlink inter-cell interference.In this paper,we propose two-layer precoding scheme.First layer is designed to avoid the inter-cell interference.Second layer is designed to manage the multiuser interference based on the equivalent channels.Simulation result shows that proposed scheme has potential gains compared with RV scheme.