An Energy Efficiency Maximization Scheme for the Wireless Information and Power Transfer System With MU-MIMO Uplink Access

In this paper, we consider the maximization of energy efficiency in the wireless information and power transfer system with multi-user multiple-input/multiple-output (MU-MIMO) as its uplink multiple access technique. We maximize the energy efficiency by jointly optimizing transmit power and its transfer duration. Different throughput requirements and MIMO channel situations of terminals are considered in the optimization problem, which makes the optimization problem closer to the practical system. We transform the complicated fractional optimization problem into an equivalent integral expression, and then employee the Lagrange dual method to solve the problem. Simulation results demonstrate that, the joint parameters optimization with the MU-MIMO mode achieve higher energy efficiency than the single parameter optimization with the multiple-input/single-output multiple access mode.