Throughput Performance of Downlink MIMO Transmission with Multi-Beam Selection using a Novel Codebook

We have been proposing multi-beam MIMO (MB-MIMO) as an evolved UTRA downlink MIMO scheme for 3GPP long term evolution (LTE). MB-MIMO is a pre-coding MIMO scheme that uses a simple combination of multi-beam multiple-data-stream transmission and user equipment (UE)-based adaptive beam selection. The scheme benefits from its simple uplink feedback signaling, because MB-MIMO requires only a subset of the beam (codebook) indices to be fed back. However, a hardware calibrator (HW-CAL), which increases the complexity of RF components at a transmitter, should be installed in order to achieve a high beam-forming gain with a small codebook size. In this paper, we propose a novel codebook design for MB-MIMO, which realizes a superior performance without any HW-CAL with a small increase of the codebook size and the feedback signaling. We performed a computer simulation to evaluate the throughput performance of the proposed scheme, considering the phase variation between antenna elements in a spatially distributed multi-path fading channel model.