A Novel Equivalent Baseband Channel of Hybrid Beamforming in Massive Multiuser MIMO Systems

Abstract

The conventional full radio frequency (RF) configuration appears to be unfeasible in massive multiple-input-multiple-output (MIMO) systems due to the still-exorbitant energy consumption of RF chains at millimeter wave frequencies. In this letter, we address this challenge by proposing a novel two step hybrid beamforming scheme for the downlink massive multiuser MIMO systems. Our purpose is to maximize the overall spectral efficiency with limited RF chains. In the first step, we aim to find an equivalent baseband channel by maximizing its capacity through the analog RF processing. In the second step, the inter-user interference is eliminated by the block diagonalization (BD) technique. Simulation results demonstrate that the proposed scheme can achieve a higher capacity than the traditional BD scheme with much fewer number of RF chains.