Hybrid Precoding for Mixture Use of Phase Shifters and Switches in mmWave Massive MIMO

A variable-phase-shifter (VPS) architecture with hybrid precoding for mixture use of phase shifters and switches, is proposed millimeter wave massive multiple-input multiple-output communications. For the VPS architecture, a design (HPD) scheme, called VPS-HPD, to optimize phases according channel state information by alternately optimizing analog precoder digital precoder. To reduce computational complexity VPS-HPD low-complexity HPD scheme (VPS-LC-HPD) including alternating optimization in three stages then proposed, where each stage has closed-form solution can be efficiently implemented. hardware introduced large number we consider group-connected propose problem divided into multiple independent subproblems subproblem flexibly solved or VPS-LC-HPD scheme. Simulation results verify effectiveness schemes show that achieve satisfactory spectral efficiency performance reduced complexity.