Research On Millimeter Wave Massive MIMO Hybrid Precoding Technology

Millimeter-wave communication systems equipped with large-scale antenna arrays meet the higher-speed and higher-capacity communication needs in the future wireless communication system,which is an important direction for future wireless communication technology research.It is necessary to configure a radio frequency link equal to the number of antennas for the traditional precoding technology,which causes the hardware cost and power consumption to double,which is not conducive to the implementation of massive MIMO.Therefore,the precoding scheme of the hybrid architecture becomes effective solution for the millimeter wave massive MIMO systems.This paper studies mainly hybrid precoding algorithms in millimeter-wave massive MIMO systems.For the problem of high computational complexity of existing fully-connected hybrid precoding algorithms,a fully-connected hybrid precoding scheme without iterative search ideas is proposed.At the same time,based on the idea of alternating iterations,a partially-connected hybrid precoding algorithm with a trade-off between algorithm complexity and system performance is proposed.The main contents in this paper are as follows:Firstly,this paper discusses the channel model and channel capacity in millimeter-wave massive MIMO systems,analyzes the precoding technology in a traditional MIMO system,and shows through theoretical analysis that the traditional precoding technology cannot be applied to a millimeter-wave massive MIMO system.At the same time,two hybrid precoding algorithm structures are introduced:fully-connected and partially-connected.Secondly,this paper studies fully-connected hybrid precoding algorithms Aiming at the problem that the complexity of the algorithm is too high due to the iterative search process in the classic OMP hybrid precoding algorithm,a low complexity fully-connected hybrid precoding algorithm without iteration is proposed.The algorithm obtains a set of orthogonal basis through the singular value decomposition of the channel response matrix,and then selects the basis vector of the precoding matrix based on the correlation between the basis vector and the optimal digital precoding matrix,so that the construction of the hybrid precoding matrix can be completed without iterative search.Simulation results show that the proposed algorithm can approach the system spectral efficiency of the OMP hybrid precoding algorithm,and the computational complexity of the algorithm is much smaller than the OMP hybrid precoding algorithm.Finally,this paper discusses partially-connected hybrid precoding algorithm.By analyzing the precoding algorithm based on successive interference cancellation(SIC)and the semi-positive definite relaxation-alternation minimization(SDR-AltMin)algorithm,it is pointed out that the algorithm cannot properly compromise the system performance and the calculation complexity of the algorithm,a low-complexity alternating iterative(Lc-Alt)algorithm is proposed.Simulation results show that the spectral efficiency of the proposed algorithm is better than the SIC-based algorithm and slightly worse than the SDR-AltMin algorithm,but the computational complexity of the algorithm is much less than the SDR-AltMin algorithm,which realizes the trade-off between the computational complexity of hybrid precoding algorithms and system performance in partially-connected structure.