Joint RF Precoding and Beam Selection Design for Uplink mmWave Beamspace MIMO Systems

Phase-only radio frequency (RF) precoding and lens antenna array-based beam selection are two promising low-hardware-cost technologies for millimeter-wave (mmWave) multiple-input multiple-output (MIMO) systems. This letter aims to jointly design users' RF precoders and base station's beam selection network to maximize the uplink sum rate (SR) of mmWave MIMO systems. For the sake of tackling the formulated mixed-integer optimization problem, a fractional programming-based iterative algorithm is developed via capitalizing on the Riemannian gradient (RG)-based and penalty-based methods. In addition, a low-complexity algorithm is proposed at the expense of a slight SR performance loss, which combines the stepwise refinement-based beam selection scheme with the RG approach. The convergence of the proposed algorithms are discussed and their effectiveness is illustrated by numerical results.

Automated summary

This letter aims to jointly design users' RF precoders and base station's beam selection network in order to maximize the uplink sum rate of mmWave MIMO systems. An iterative algorithm based on fractional programming, Riemannian gradient, and penalty method is developed, and a low-complexity algorithm is also proposed. The effectiveness of the proposed algorithms is demonstrated through numerical results.