Abstract
We consider power efficient scheduling and precoding solutions for
multiantenna hybrid digital-analog transmission systems that use
Time-Modulated Arrays (TMAs) in the analog domain. TMAs perform
beamforming with switches instead of conventional Phase Shifters (PSs).
The extremely low insertion losses of switches, together with their
reduced power consumption and cost make TMAs attractive in emerging
technologies like massive Multiple-Input Multiple-Output (MIMO) and
millimeter wave (mmWave) systems. We propose a novel analog processing
network based on TMAs and provide an angular scheduling algorithm that
overcomes the limitations of conventional approaches. Next, we pose a
convex optimization problem to determine the analog precoder. This
formulation allows us to account for the Sideband Radiation (SR) effect
inherent to TMAs, and achieve remarkable power efficiencies with a very
low impact on performance. Computer experiments results show that the
proposed design, while presenting a significantly better power
efficiency, achieves a throughput similar to that obtained with other
strategies based on angular selection for conventional architectures.