A novel beamforming scheme in FD-MIMO systems with spatial correlation

Compact structure of the large-scale antenna array and low power angular spread (PAS) in vertical dimension improve the fading correlation of wireless channel dramatically in full-dimension multiple input multiple output (FD-MIMO) systems. Whereby beamforming (BF) can fully exploit the quasi-static spatial correlation to reduce dependence on the instantaneous channel state information at the transmitter (CSIT) and simplify the complexity of signal process, but also incur a loss of system performance. In this paper, we analyze the potential of exploiting spatial correlation in FD-MIMO systems, and propose an interesting spatial-correlation-based partial-channel-aware beamforming (SP-BF) scheme. Through the rationale of Givens rotation, SP-BF leverages the CSIT of partial channels, i.e., reduced-dimension channel vector, to further boost the system performance achieved by exploiting the spatial correlation. By applying this scheme, FD-MIMO in frequency division duplex (FDD) systems, where no channel reciprocity could be exploited, can make a tradeoff between the system performance and the overhead of acquiring CSIT. In addition, we validate the proposed scheme by virtue of the Monte Carlo simulations.