Throughput Performance of Pre-coding MIMO Transmission with Multi-Beam Selection

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 signalling, because MB-MIMO requires only a subset of the beam indices to be fed back. In this paper via computer simulation, we compare the performance of MB-MIMO and closed-loop MIMO that utilizes antenna selection only without beam-forming at the transmitter. In this comparison we consider the correlation between antenna elements in a temporally and spatially dispersed multi-path channel. Simulation results revealed that MB-MIMO has superior performance due to its beam-forming gain, even with limited feedback signalling. In this paper, we also introduce the MB-MIMO scheme using the cross-polarized (X-pol) antenna arrays and demonstrate its throughput performance comparing to the MB-MIMO using the 4-antenna linear array.