Research On Digital Pre-distortion Technology Of MIMO Time Division Multiplexing

People have made breakthroughs one after another in the field of communication,from the 2G,3G,4G era to the current 5G era,6G technology has even been put on the agenda.For this reason,in a real base station device,it is difficult to avoid some kind of non-linear distortion when amplifying the basic range signal with a power amplifier.In order for the entire communication system to work well,the pace of the power speaker must be.Currently,retreat and feedforward are the main methods of documents,but in recent years,researchers have conducted more research on pre-modern techniques,which have become a hot topic.Pre-distortion technology can be different from the analog predistortion technology and digital pre-distortion technology.The latest 5G solutions include device-centered,large-scale MIMO and so on.Based on the above problems,here we suggest the technology to achieve a digital MIMO predistation based on time division several times using FPGA.This scheme can carry out adaptive predistortion and reduce the number of linear modules by time-division multiplexing.The main points of action and innovation in this text mainly include the following areas:(1)This paper analyzes the shared operating models of power speakers.Classic Voltera series models,DDR models,GMP models and DDMP models were compared and analysed.We analyzed the composition,pros and cons of each model,and suggested a model to balance the accuracy and complexity of the model.The advantages of DDRMP are obtained by analyzing the precision and complex rate of the model.The simulation was validated by MATLAB that the MPDDR model has corresponding advantages compared with the DDMP model with the same complexity but improved NMSE of0.63 d B.(2)The structure of lookup table of digital pre-distorter is researched in this thesis.A paired comparison is done among the polynomial structure digital pre-distorters and the lookup table structure digital pre-distorters mentioned in the literature.Analysis of how to search the look-up table is a quantity,including a uniform quantizing and a uniform quantizing interpolation.We came up with a new way of standardized muzzling search tables based on secondary completion.Compared to uniform muzzle method,the linear effects is clearly improved 5d B,time indexing and data storage capacity on balanced data.(3)Here we suggest the embodiment of the digital pre-distortion system based on time division several times,and three platforms are built based on AD9371 RF transceiver board of ADI Company,VC707 development board of Xilinx Company and FEM C fourchannel RF transceiver board of the laboratory.Mainly divided into FPGA devices and parts of SDK software,devices including previous levels of data after unit collection,data combination module,digital predistortion module(including amplitude and phase separation,look-up table and predistortion signal computing),PL and PS data interaction module,data acquisition module and time-division multiplexing module,software part includes signal acquisition,coefficient calculation and lookup table generated,and other functions.Finally,the simulation results were taken in MATLAB to make sure the prestation effect is ideal.ACPR met the needs of communication standard-45 d Bc.The experimental results of the last three platforms show that the designed digital predistortion system is in line with the expectation and can linearize the power amplifier effectively,so that the ACPR index can meet the requirements of the communication standard-45 d Bc.