Rate-Energy Tradeoff for SWIPT Systems with Multi-User Interference Channels under Non-Linear Energy Harvesting Model

This paper investigates the rate-energy (R-E) region of simultaneous wireless information and power transfer (SWIPT) systems for multi-user interference channels under the nonlinear energy harvesting (EH) model, where multiple transmitting users simultaneously broadcast signals to multiple receiving users. In order to achieve green communication design, we aim to characterize the tradeoff between the energy transfer and ergodic capacity and furthermore explore the influence of interference intensity on the considered system. Specifically, considering both time switching (TS) and power splitting (PS) receiver architectures, we formulated an optimization problem to derive the boundaries of R-E regions. As the optimization problem is non-convex and the employ of the nonlinear EH model makes it more difficult, we first apply efficient variable substitutions and Lagrangian duality method to transform it into equivalent convex problem, and then employ a low-complexity algorithm to obtain the optimal allocation scheme. Compared with the systems under traditional linear EH model, the R-E regions of the considered system is superior to reflect the features of the practical EH circuits. Due to the multi-user interference channels and the limitations of practical circuit environment, the system also shows different R-E tradeoff performance with different interference intensities.