Implementation of full-dimensional MIMO (FD-MIMO) in LTE

Data-centric mobile devices poses challenges to operators on sustaining the rapid growth of mobile traffic. Recently, full-dimensional MIMO (FD-MIMO) emerges as a promising technique to significantly increase spectrum efficiency and has been proposed and investigated in 3GPP LTE (Long Term Evolution) and LTE-advanced (LTE-A). In FD-MIMO systems, an evolved Node B (eNB) deploys a large number of active antenna elements in a 2-dimensional (2D) grid and is capable to support many users on the same bandwidth simultaneously. In this paper, we propose a FD-MIMO framework within LTE/LTE-A standards and discuss key challenges including downlink preceding, antenna virtualization and channel quality indicator (CQI) prediction. Furthermore, we explore feasibility of implementing FD-MIMO in frequency division duplex (FDD) systems. Based on system-level simulations, FD-MIMO is shown to attain 2-5 times cell average throughput gain as well as cell-edge throughput gain, compared with 4G LTE system.