Research On Three Dimensional MIMO System And Its Precoding Methods

With the development of wireless communication technology, people start to enhance the performance of wireless communication further, especially in the study of the fifth generation of wireless communication technology. In order to enhance the performance of wireless communication transmission link, exploiting the channel’s degrees of freedom of wireless channel has become an important research hotspot, 3D MIMO(Three Dimension of Multi-Input and Multi-Output) communication technology can be regarded as an effective way to realize the use of elevation dimension, and the technology of antennas’ down tilt can make the users’ differentiation much clearer, and also can let the base station’s antenna selectively adjust its covered area, which is an effective way to suppress interference between cells. So 3D MIMO modeling, as well as the application of the vertical dimension of MIMO system, is an important subject in the research of wireless channel.At present for the pre-coding technology research, most of them are only for horizontal dimension. Due to the difference of scatters’ distribution in vertical and horizontal dimension in the 3D MIMO channel, therefore, the pre-coding techniques in vertical dimension, should take the characteristics of the wireless channel’s vertical dimension into consideration. And in this article, from two aspects of 3D MIMO pre-coding techniques are studied, respectively, and we put forward two suitable pre-coding technologies for the vertical dimension: one is based on instantaneous channel characteristics, and the other is a new pre-coding method in the beam domain of vertical dimension. And make the 3D MIMO get a better performance.This paper firstly describes the research background, as well as the technical status of spatial 3D channel modeling, and introduces our research direction. Then, we introduce the layout of 3D MIMO system. And the 3D MIMO channel modeling method is introduced in detail, including the introduction of slow fading channel, and the introduction of the modeling methods for fast fading channel. And in this part, we introduce the influence of the exploiting channel model’s vertical dimension in detail.And then this paper is mainly focus on the verification of our simulated 3D MIMO. We research and analyze the channel’s parameters, and calibrate with the 3GPP standard reference parameters, which prove the accuracy of our channel simulation. And then we put forward two pre-coding schemes of 3D MIMO, that is, one is based on instantaneous channel characteristics, and the other is the coordinated 3D beam-forming method for interference suppression based on greedy algorithm. We analyze the causes of the optimal problem and the optimization process, and finally we put forward this scheme based on greedy algorithm. And next the correctness of those algorithms is verified by simulation. The simulation results also show that, compared with common two-dimensional channel scheme and other three-dimensional channel beam-forming strategies, the beam-forming schemes put forward by us in this paper can bring obvious gain effect.