Hybrid precoding for DL massive MU-MIMO systems with distributed antenna deployments

Massive Multiple-Input-Multiple-Output (MIMO) using distributed antenna systems (DASs) have emerged as a promising architecture for future mobile communications, because of their advantage in improving the spectral efficiency and power efficiency. Unfortunately, the RF transceivers introduce huge cost due to the higher complexity of the hardware with the antennas increase. In this paper we consider a massive MU-MIMO system which encompasses an hybrid beamforming architecture and distributed antennas. In the hybrid beamformer the analog beamformer controls the phase in the corresponding phase shifter of a given antenna and the zero-forcing baseband processing is applied afterwards over the effective channel. Geometrical one ring scattering model is adopted for the channel and the results show that, relative to the co-located massive MU-MIMO with the same antenna configuration, MU-MIMO-DAS alternative allows to achieve a significantly higher performance.