Energy-Efficient Hybrid Symbol-Level Precoding via Phase Shifter Selection in mmWave MU-MIMO Systems

Alireza Haqiqatnejad, Farbod Kayhan, Bjorn Ottersten
2020 GLOBECOM 2020 - 2020 IEEE Global Communications Conference  
We address the symbol-level precoding design problem for the downlink of a multiuser millimeter wave (mmWave) multiple-input multiple-output wireless system. We consider a hybrid analog-digital architecture with phase shifter selection where a small-sized baseband precoder is followed by two successive networks of analog on-off switches and variable phase shifters according to a fully-connected structure. We jointly optimize the digital baseband precoder and the states of the switching network
more » ... n a symbol-level basis, i.e., by exploiting both the channel state information (CSI) and the instantaneous data symbols, while the phase-shifting network is designed only based on the CSI. Our approach to this joint optimization is to minimize the Euclidean distance between the optimal fully-digital and the hybrid symbollevel precoders. It is shown via numerical results that using the proposed approach, up to 50 percent of the phase shifters can be switched off on average, allowing for reductions in the power consumption of the phase-shifting network. Adopting appropriate power consumption models for the analog precoder, our energy efficiency analysis further shows that this power reduction can substantially improve the energy efficiency of the hybrid precoding compared to the fully-digital and the state-of-the-art schemes. Index Terms-Energy efficiency, hybrid symbol-level precoding, multiuser mmWave massive MIMO, phase shifter selection.
doi:10.1109/globecom42002.2020.9322573 fatcat:tlmwbdc53nal7ml7gwlfagrzcq