Historical PMI Based Multi-User Scheduling for FDD Massive MIMO Systems

Abstract

Massive multiple-input multiple-output (MIMO) system, in which base stations are equipped with a large number of antennas in a two-dimensional (2D) antenna array, is one of the most promising technologies to improve the spectral efficiency of cellular networks. Since there is no channel reciprocity, the frequency-division duplexing (FDD) massive MIMO system has to obtain channel state information (CSI) with the help of uplink feedback. However, in practice, there are several challenges for the implementation of FDD massive MIMO system, such as feedback overhead and delay. In this paper, we begin with the virtual sectorization using CSI- Reference Signal (RS) beamforming scheme to illustrate the implementation of FDD massive MIMO in the standard transparent manner, and then we describe the potential performance degradation caused by feedback delay. To cope with this issue, we propose a historical precoding matrix indicator (PMI) based multi-user scheduling algorithm to enhance the system performance. By utilizing system-level simulator, we further present the effectiveness of the proposed algorithms.