Optimizing Efficient Energy Transmission on a SWIPT Interference Channel Under Linear/Nonlinear EH Models

In this paper, we consider simultaneous wireless information and power transfer (SWIPT) in a multiple-input single-output interference channel (IC) system where the power-splitting (PS) receivers utilize linear/nonlinear energy-harvesting (EH) models. The functions that express the relationship between the input radio frequency power and the output direct current harvested energy of the EH circuits are usually assumed to be linear in recent SWIPT works, while the nonlinear function is suitable for practical data. In a SWIPT IC system, two important targets are sum harvested energy maximization and harvested energy efficiency maximization at the PS receiver, and they are investigated under linear/nonlinear EH models. Thus, some nonconvex resource allocation problems with the two targets and linear/nonlinear EH models are formulated to jointly optimize beamforming vectors at the transmitters and the PS ratios at the receivers. By exploiting a successive convex approximation method and a semidefinite relaxation (SDR) technique, iterative algorithms are proposed to obtain local optimal solutions. Interestingly, the optimal solution to the subproblem is proven to satisfy the rank-1 constraint of the SDR technique. Finally, numerical experiments illustrate effective performance from the proposed solutions, in comparison with some special schemes.