Sum rate maximizing for SWIPT with limited battery capacity

In this paper, we consider a multiuser multiple-input single-output downlink system for Simultaneous Wireless Information and Power Transfer(SWIPT). Different from the conventional battery-free power splitting strategy, the harvested energy can be buffered in a battery before consumption. Accordingly, increasing battery lifetime, where the base station is powered by sustainable energy. A sum rate optimization problem for SWIPT with battery constraint while ensuring user's quality of service and minimum harvested energy is formulated. Moreover, user quality and minimum harvest energy are ensured due to application of a sum rate optimization for SWIPT with battery constraint. It is a non-convex problem that needs to optimally design the transmit Beamforming(BF) vectors and battery constraint factors. To address this perplexing problem, we formulate it as an inner loop and outer loop problem. In inner loop, we propose an algorithm to convert the original problem into an iterative second-order cone program(SOCP) form to get the optimal value of transmit (BF) after the sum rate converges in a few iteration. For the outer loop, battery model for front-end decoding is designed and its relation with maximum user rate during different frames is analyzed. Simulation results show that our proposed algorithm not only improves the usage of batteries, but also enhances the average sum rate.