Practical channel acquisition for massive MIMO systems in LTE

Abstract

In this paper, practical CSI acquisition methods for massive MIMO systems are investigated. The implementation issues of channel reciprocity based feedback in TDD are discussed, and a two-dimension feedback mechanism for FDD is proposed where the horizontal and vertical domain channels are reported separately. System level evaluation results demonstrate that massive MIMO with the two-dimensional feedback mechanism provides realistic gains over antenna virtualization beamforming, whereas additional gain is feasible through UL/DL channel reciprocity.