Performance Evaluation of Nonlinear Precoding Based on 44 GHz Band Experiments for 5G Ultra High Capacity Massive MIMO

For 5G massive MU-MIMO (Multi-User Multiple-Input and Multiple-Output) systems in high frequency bands, a favorable scenario is a line-of-sight (LOS) environment where the direct paths dominate the spatial channels. In the LOS environment, spatial correlation between user equipments (UEs) tend to be high and its capacity decreases, especially in the case where we have densely distributed UEs. The authors have already proposed a nonlinear precoding scheme incorporating block multi- diagonalization (NL-BMD) for highly correlated channel and demonstrated its effectiveness by computer simulation. In this paper, the authors present indoor propagation measurement results using a channel sounding system with 44 GHz active phased array antenna in the condition that UEs are sparsely and closely distributed. In addition, this paper shows the spectral efficiency of NL-BMD based on the measurement results compared with the conventional precoding schemes.