Wireless energy transfer in downlink and wireless communications in uplink for multi-user MIMO networks

In this paper, the energy is wireless transferred in the multi-user multi-input multi-output (MU-MIMO) broadcast channel and the information is wireless transmitted in the MAC MU-MIMO channel. The energy efficiency metric and the spectral efficiency objective are theoretically traded off for the wireless energy and information transmission networks, which results in the analytical expression. Moreover, the number of the transmit antennas and that of the mobile terminals are optimized to the closed form expression by maximizing the energy efficiency with the quality of service (QoS) in terms of the required spectral efficiency. Finally, the optimal energy efficiency of the whole networks is obtained with the optimized number of both antennas and mobile terminals. The key feature of this paper is the analytical expression of the power allocation for the best energy efficiency. Numerical simulations demonstrate the effectiveness of the proposed method for the MU-MIMO wireless energy and information transmission networks.