Energy harvesting balancing technique for robust beamforming in multiuser MISO SWIPT system

In this paper, a novel energy harvesting (EH) balancing technique for robust beamformers design in multiuser multiple-input single-output (MISO) broadcast system with simultaneous wireless information and power transfer (SWIPT) is proposed. Our design objective is to maximize the worst energy receiver harvested power under both the signal-to-interference-and-noise ratio (SINR) constraints at information receivers and total transmission power constraints at the transmitter. Considering imperfect channel state information (CSI) at the transmitter, the aforementioned max-min problem for EH fair robust beamformers design is non-convex in general. In order to solve this non-convex optimization problem, in this paper, we first derive equivalent conditions for the EH constraints and SINR constraints, and then convert original non-convex optimization problem into a relaxed semi-definite programming (SDP) problem, which can be solved efficiently by standard interior-point methods. Moreover, we propose an iterative algorithm based on bisection method to obtain the robust beamforming solutions. Finally, simulation results are provided to demonstrate the effectiveness and robustness of our algorithm.