HAP Massive Mimo Two-stage Precoding Design

With the continuous progress of the times,people have put forward higher requirements for mobile communication data transmission rate and service quality.It is required that the communication system can obtain better power efficiency while greatly improving the spectrum efficiency.The large-scale multiple-input multiple-output(MIMO)technology that came into being at the time can be used to communicate with multiple users under the same time and frequency resources by configuring a large-scale antenna array at the base station.Massive MIMO can increase the system capacity by increasing the number of base station antennas.The theory proves that when the number of base station antennas is close to positive infinity,the uncorrelated noise of the system can be ignored and the system performance tends to be optimal.In recent years,a new communication platform is gradually entering people's field of vision.He is stratospheric communication.Stratospheric communication refers to a communication system that uses high altitude platforms(HAPs)located in the stratosphere instead of satellites or the ground as base stations.Taking advantage of its small multipath fading and large coverage area,the establishment of a stratospheric massive MIMO platform will bring huge gains to the communication system.Therefore,how to solve the interference problem caused by the excessive number of antennas and the number of users in a massive MIMO system has become a top priority.This article will focus on stratospheric massive MIMO communication systems,focusing on the design of the two-layer precoding matrix under the new platform.The work of this article is as follows:First,the article will study and introduce the massive MIMO communication channel model under the stratospheric platform.Based on the established stratospheric communication model,it analyzes the performance gains brought by large-scale antenna arrays and the necessity of building a stratospheric platform,analyzes the causes of interference caused by stratospheric massive MIMO,and introduces corresponding precoding techniques.Then,the article studies the design of two-stage precoding in stratospheric massive MIMO system.Based on the transmission characteristics of JSDM,this paper presents a user grouping mode suitable for high-altitude platforms and combines it with JSDM two-stage precoding and simulates the scheme.This paper studies a two-stage precoding design scheme based on SLNR maximization.In order to effectively eliminate the intra-cell interference(IUI)and inter-cell interference(ICI)under the stratospheric platform,and reduce the high complexity caused by high radio frequency numbers.This paper presents a two-layer precoding design scheme.The content of the scheme includes outer precoding based on the signal-to-noise-noise ratio(SLNR)design to eliminate ICI,and then the actual channel and the outer precoding are used as equivalent channels.The inner layer is designed based on Zero Forcing(ZF)technology.Precoding the matrix to eliminate IUI.