Research On Precoding Of Wireless Massive MIMO System

A variety of new wireless business explode with the development of smart phones,such as smart hardware,Internet of Things (IoT),Internet Med,Virtual Reality (VR),such technologies put forward new demands for wireless communication technology.Common 4G system cannot met the needs of system rates, time delay and reliability.As radio frequency is nonrenewable resources, and environmental groups claim that we should reduce power consumption for a better green world. As the key technique of 5G communication system, massive MIMO can significantly improve spectral efficiency and energy efficiency of the system, is currently one of the most popular research topic in the field of wireless communications.As we considered the problems in massive MIMO's actual deployment, the following two aspects are mainly studied:Firstly, in view of system energy efficiency problem: we considered the antenna selection problem in base station deployment, we make a survey on antenna selection algorithm for MIMO system and known massive MIMO system in detail, and proposed an algorithm based on genetic algorithm and heuristic beamforming, then we simulated the performance of this algorithm and make an analysis.Secondly, as to the problem of system complexity, we take the precoding scheme in massive MIMO system into consideration. Although linear precoding scheme can obtain performance approximate to nonlinear scheme, and reduce the complexity of implementation at the same time. But for massive MIMO, as a large scale of antennas were deployed on base station, even linear precoding scheme has an unimaginable computational complexity. Aiming at the complex part of linear precoding scheme:inverse of channel matrix, we proposed a precoding scheme based on Cholesky decomposition, and simulated the performance of it.