Robust Beamforming for Wireless Information and Power Transmission

TL;DR

This paper proposes a robust beamforming method for multi-antenna wireless systems that simultaneously transmits information and power, optimizing energy harvesting under imperfect channel knowledge with an efficient SDP-based solution.

Contribution

It introduces a novel robust beamforming approach that guarantees performance under channel uncertainties and proves the relaxation is tight, enabling optimal solutions.

Findings

The proposed algorithm maximizes worst-case energy harvesting.

The relaxation approach yields rank-one solutions, ensuring optimality.

Simulation results confirm the effectiveness of the method.

Abstract

In this letter, we study the robust beamforming problem for the multi-antenna wireless broadcasting system with simultaneous information and power transmission, under the assumption of imperfect channel state information (CSI) at the transmitter. Following the worst-case deterministic model, our objective is to maximize the worst-case harvested energy for the energy receiver while guaranteeing that the rate for the information receiver is above a threshold for all possible channel realizations. Such problem is nonconvex with infinite number of constraints. Using certain transformation techniques, we convert this problem into a relaxed semidefinite programming problem (SDP) which can be solved efficiently. We further show that the solution of the relaxed SDP problem is always rank-one. This indicates that the relaxation is tight and we can get the optimal solution for the original problem. Simulation results are presented to validate the effectiveness of the proposed algorithm.