Performance Evaluation of Beamformed Spatial Multiplexing Transmission in Millimeter-Wave Communication Channels

This article deals with the study on the performance of the hybrid transmission scheme combining both beamforming and spatial multiplexing. Specifically, the capacity of the hybrid scheme is evaluated and compared to that of the just beamforming scheme in line-of-sight and multi-path channels. Two kinds of the hybrid schemes are considered: the shared antenna architecture where each antenna processes all data streams and the split antenna architecture where each antenna processes only one data stream. The effects of the channel parameters such as the antenna spacing, the existence of reflecting paths, etc. on the capacity and the optimal beams and powers are examined. The frequency-selectivity property of the capacity and the optimal beams and powers is also investigated. In this study, a scenario is considered where the same analog RF beamformer is applied to all subcarriers but the digital baseband power allocation is executed individually at each subcarrier.