Hybrid Beamforming under Equal Gain Constraint for Maximizing Sum Rate at 60 GHz

Millimeter wave (mmWave) band is characterized by very high path loss. To overcome this, spatial multiplexing and beamforming can be employed and in mmWave due to the small wavelength, large antenna arrays can be used to provide the required gain. However, unlike the traditional microwave systems it is not feasible to afford one RF chain per antenna. To overcome this practical limitation, hybrid beamforming can be utilized and the complexity of the transceiver can be reduced by implementing the RF domain processing using only the analog phase shifters. In this paper, we propose a two step approach to design a hybrid beamforming architecture. In this approach, we first design the baseband beamforming and then the RF domain beamforming is realized using an iterative algorithm. Finally, the proposed algorithm is validated by providing numerical examples by means of simulation.