Hybrid Beamforming for Multiuser Millimeter Wave MIMO-OFDM Systems

Hybrid analog and digital beamforming (HBF) for large-scale antenna arrays with limited radio frequency chains has been regarded as one of the promising candidates for future wireless communications. Due to the limitation of hardware, this problem becomes more challenging compared with the design of conventional digital beamforming schemes. In this paper, we investigate the HBF design for broadband multiuser millimeter wave multiple-input multiple-output systems. By utilizing the alternating minimization method and taking the weighted sum mean square error minimization criterion, a strictly convergent algorithm based on the manifold optimization method is proposed to efficiently tackle the non-convex problem. The algorithm is applicable to the analog beamforming design in both the fully-connected architecture and the partially-connected architecture. Simulation results demonstrate the fast convergence and excellent performance of the proposed scheme.