Performance evaluation on beam shapes of a large MIMO system

Abstract

The massive MIMO technology which generates many sharp beams is known as a promising technology to accommodate rapidly-increasing traffic in mobile radio. In massive MIMO systems, there have already been a number of papers on 2-step beamforming where precoding matrix is calculated in a limited beam space after beam selection. In such a case, it is very important to select proper beams. Then, the beam shape affects the system performance. In the paper, we evaluate the achievable throughput performance for different beam-shaping schemes: a discrete Fourier transform (DFT) beam and Chebyshev weighted beams. The simulation results show that the DFT beam is a good choice although the optimum beam depends on the channel situation.