Max-min fair robust beamforming design for multi-user MISO SWIPT systems

Abstract

This paper proposes a robust transmission design for simultaneous wireless information and power transfer (SWIPT) in a multiuser multiple-input single-output (MISO) broadcast system, under the assumption of imperfect channel state information (CSI) at the transmitter. Our design objective is to maximize the minimum harvested energy of all the receivers by jointly optimizing the transmit beamforming vectors and the power splitting ratios while guaranteeing the signal-to-interference-and-noise ratio (SINR) and total transmit power constraints. The aforementioned max-min problem is non-convex due to the existing of infinite number of constraints, and thus it is difficult to solve. To tackle it, we first convert it into an easier non-convex problem with finite constraints by using some certain transformation techniques. Then, with the aid of the semidefinite relaxation (SDR) technique, we further obtain a relaxed semidefinite programming (SDP) problem, which is convex and thus can be solved efficiently by using interior point methods. Finally, simulation results are provided to validate the robustness and effectiveness of the proposed scheme.