TWO-STAGE LIMITED FEEDBACK FD-MIMO WITH LAYERED/CONCATENATED PRECODING AND GRASSMANNIAN QUANTIZATION

Full dimension MIMO (FD-MIMO) promises significant beamforming gains and multi-user multiplexing capabilities, provided accurate channel state information (CSI) at the transmitter (CSIT) is available. Accurate CSIT, however, is hard to obatin especially in frequency division duplex systems. We propose a two-stage limited feedback method that combines a sparse channel decomposition with low-dimensional Grassmannian differential quantization to obtain ccurate CSIT in time-correlated channels with reasonable training overhead.