Beamforming Based on Energy State Feedback for Simultaneous Wireless Information and Power Transmission

Abstract

With simultaneous wireless information and power transfer, the energy of RF signal can be used effectively for the self-sustained operation of wireless devices. In practical applications, power splitting method can be used for simultaneous wireless information and power transmission (SWIPT) between base station and multi-user. Different user systems have different energy consumption, so users with insufficient power need more energy transmission to supplement their power. Nowadays, the beamforming strategy of simultaneous wireless information and energy transmission does not consider the problem of insufficient power at the terminal. This paper proposes a energy state feedback method to optimize simultaneous wireless information and power transmission system. Through the joint design optimization of beamforming and power splitting, the power transmission of users with insufficient power is added, and the minimized transmission power optimization is done under the conditions of satisfying SINR and energy harvesting constraints by utilizing the channel state information and node power information of each node. This optimization model is difficult to solve. In order to solve this problem, the concept of reserve group is introduced. When the optimization model cannot be solved, the users with the worst channel state of the node are put into the reserve group. These users do not participate in the optimization first. After the new channel state information is obtained, the optimization model is established again. If the problem can be solved, the transmission power of base station doesn’t reach the maximum power, some users in the reserve group is added to continue to optimize, if it has reached the maximum power of base station transmission, it is not optimizing, so as to maximize the optimization of all users and improve system performance.