Regularized Zero-Forcing Aided Hybrid Beamforming for Millimeter-Wave Multiuser MIMO Systems

This paper considers hybrid beamforming consisting of analog beamforming (ABF) coupled with digital baseband beamforming (DBF) which is designed for multi-user (MU) multiple input multiple output (MIMO) millimeter-wave (mmWave) communications. ABF uses a limited number of radio frequency (RF) chains and finite-resolution phase-shifters to alleviate the power consumption at the base station (BS), while DBF uses either zero-forcing beamforming (ZFB) or regularized zero forcing beamforming (RZFB) to restrain MU interference. The joint design of ABF and DBF constitutes a computationally challenging mixed discrete continuous optimization problem. The paper develops efficient algorithms for its solution, which iterate scalable-complex expressions. Furthermore, we conceive a new class of MU RZFB for attaining higher rates. Simulations are provided to demonstrate the viability of the proposed algorithms and the advantages of the conceived RZFB.

Automated summary

This paper focuses on hybrid beamforming for multi-user MIMO millimeter-wave communications, combining analog beamforming (ABF) and digital baseband beamforming (DBF). ABF reduces power consumption at the base station (BS) by using a limited number of radio frequency (RF) chains and finite-resolution phase-shifters, while DBF employs zero-forcing beamforming (ZFB) or regularized zero-forcing beamforming (RZFB) to mitigate multi-user interference. The joint design of ABF and DBF presents a computationally challenging optimization problem, and this paper develops efficient algorithms to solve it. Additionally, a new class of MU RZFB is proposed for achieving higher rates, and simulations confirm the effectiveness of the proposed algorithms and the advantages of the conceived RZFB.