Design Of Hybrid Precoding Scheme Based On Massive MIMO

Mobile communication system plays a vital role in today's society,with the development of electronic technology and the rise of various new businesses,more and more stringent requirements are required for the spectral efficiency and energy efficiency of the next generation communication system.As Massive MIMO technology and millimeter wave technology can bring huge performance improvement to the system in terms of spectrum utilization and spectrum resources,they become the key technologies of the next generation communication system and have become a hot research direction of current communication field,also have received extensive attention from researchers and engineers.This paper mainly studies the Massive MIMO system,as large numbers of RF links are required for the traditional full digital precoding scheme can causes the problems of high cost,energy consumption and high computing complexity,the corresponding hybrid precoding schemes are studied.The main contents of the paper are listed as follows:(1)A scheme for using a hybrid precoder and a hybrid combiner at the transmitting and receiving terminal of the communication system is proposed for the single user Massive MIMO system,and this scheme is divided into two stages for design.The hybrid precoder is designed at the first stage,the analog precoding matrix is obtained by using the iterative algorithm firstly,and then the digital precoding matrix is designed according to the equivalent channel matrix which is generated by the interaction of the channel matrix and the analog precoding matrix.To maximize the spectral efficiency of the system,the hybrid combiner was designed at the second stage.(2)The multiuser Massive MIMO system in Rayleigh fading channel is studied,and a hybrid RZF precoding scheme for subsection design is proposed.Under the consideration of the channel noise,the inter-user interference and the system structure,the analog part and the digital part of the precoder are optimized.The analog precoding matrix is sectionally designed with the combination of MRT precoding and RZF precoding,and for the digital part,a low dimension RZF precoding is used on the basis of the equivalent channel matrix.With the method of grading design,both the number of RF chain and the dimension of the digital baseband processing are reduced.(3)The multiuser Massive MIMO system in Millimeter Wave channel is studied.Considering the multi antenna installed on the user's device,in order to reduce the number of required RF links as well as the design difficulty of the user terminal,a scheme with hybrid precoder at base station and only analog combiner at user terminal is proposed.Under the fully consideration of the characteristics of the millimeter wave channel,the analog precoding matrix and the analog combining matrix are designed at both the transmitter and receiver according to the antenna array response vectors respectively.Then,based on the generated effective channel matrix,low dimensional digital precoding matrix is designed in the base band,thus eliminating the noise and interuser interference in the system.