codebook design for LTE-A downlink system
05 September 2011
Multiple-input multiple output (MIMO) has been adopted by long term evolution (LTE) and its updated version LTE-Advanced (LTE-A) to increase the spectrum efficiency. However, the benefits of multi-user (MU) MIMO highly rely on an accurate channel knowledge at the transmitter. So proper codebook design is a key problem for LTE-A FDD downlink system. In this paper, a codebook design with phase adjustment in the precoder targeting wideband channel properties for copolarized linear antenna array is proposed. The average cell spectral efficiency and cell-edge user spectral efficiency of the proposed scheme are evaluated through system level simulation compared to the DFT based feedback scheme [6]. The results show that the proposed codebooks significantly improve feedback efficiency and system performance.