Research On Energy-Efficient Hybrid Precoding Millimeter-Wave Massive MIMO Systems

With the increasing demand of wireless high-speed data communication,mobile communication systems suffer some matters such as shortage of spectrum resources,low throughput,and high latency.Luckily,the millimeter wave band has provided abundant spectrum resources.Moreover,the millimeter-wave Massive MIMO systems which integrate massive MIMO technology and millimeter wave technology show great advantages.On one hand,the problem of shortage of spectrum resources is solved.On the other hand,large-scale antenna array is packed in small physical dimension at the base station and sufficient antenna array gain is provided.Therefore,the millimeter-wave Massive MIMO systems technolog is one of the key technologies of 5G.This paper is supported by the research project "Research on Key Technology and Business Analysis Technology of New Generation Networks" cooperated with an enterprise.This paper focuses on the research of the hybrid precoding technology in millimeter-wave Massive MIMO systems.The novel sub connected architecture is adopted in the paper and two hybrid precoding algorithms related to switch network based architecture and phase shifters based architecture respectively are proposed.The concrete research work is as follows:1)The related research on millimeter-wave massive:MIMO systems and signal precoding technology is reviewed.First of all,the millimeter wave technology and the concepts,related research directions of millimeter-wave Massive MIMO systems are elaborated.In addition,the theory,research status and corresponding advantages and disadvantages of full-digital precoding and hybrid precoding are untangled.2)For switch network based architecture,the energy-efficient hybrid precoding algorithm is proposed.The hybrid precoding is designed with the target of maximizing energy efficiency and a two-step optimization method is proposed.The original multivariate nonconvex optimization problems is decoupled and the two sub problems are solved by cross entropy optimization and an iterative optimization algorithm respectively.The simulation results demonstrate that the two-step optimization method proposed in the paper can achieve high system energy efficiency with the constraints of user QoS.3)For phase shifter based architecture,the energy-efficient hybrid precoding algorithm is proposed.The hybrid precoding is designed to maximize energy efficiency and an optimization algorithm based on channel phase extraction theory is proposed.Firstly,the design problem of analog domain is transformed into the problem of maximizing equivalent channel gain and solved by channel phase extraction algorithm.Then,the block diagonalization precoding algorithm is adopted to transform the digital precoder/receiver optimization problem into a fractional programming problem after the analog domain problem is solved.The simulation results show that the proposed precoding algorithm can achieve a good compromise between spectral efficiency and energy efficiency.