The Key Technology Of Multiple Antennas In 5G NR System

In recent years,with the rapid development of the mobile Internet,the number of mobile devices and mobile data traffic have exploded.On the basis of the 5th Generation(5G)mobile communications,this paper studies multiple input multiple output(MIMO),precoding,adaptive modulation and coding(AMC),hybrid automatic repeat request(HARQ)and MIMO detection technology for physical layer data transmission.Based on the different requirements of the 5G new radio(NR)protocols for physical uplink shared channel(PUSCH)and physical downlink shared channel(PDSCH),a complete data transmission link is built,and AMC and HARQ modules are loaded.AMC technology can adjust the modulation and coding scheme of the system relying on changes of channel conditions to maximize system throughput.HARQ is introduced to improve the adaptation accuracy as well as improve the throughput performance.At the same time,the key technology of single-user(SU-MIMO)is verified through the 5G NR link simulation platform.This paper simulates several precoding algorithms in SU-MIMO mode utilizing the5 G NR platform,including codebook-based precoding algorithm,singular value decomposition(SVD)precoding algorithm,geometric mean decomposition(GMD)precoding algorithm and eiden beamforming(EBB)precoding algorithm.Simultaneously,several selection criterias of precoding matrix indication(PMI)and rank indicator(RI)of AMC technology are simulated and compared.QR Decomposition Associated with the M-algorithm to MLD(QRM-MLD)that can approach the performance of maximum likelihood(ML)detection in the terminal is studied.To balance the performance and complexity of detection algorithm,this paper proposes an improved algorithm based on M adaptation and dynamic tree search.Considering the performance loss caused by the inaccurate of channel quality Information(CQI)reporting in SU-MIMO mode,this paper also studies the effective mapping method of CQI based on exponential effective SIR mapping(EESM)to make up the throughput loss.Finally,this paper focuses on the relevant algorithms for correcting CQI at the base station and mobile terminal,and proposes a method to modify the CQI to improve the throughput of system.