Downlink MISO-NOMA SWIPT Systems with Mini Time Slots

This paper investigates a scheme for simultaneous wireless information and power transfer (SWIPT)-based non-orthogonal multiple access (NOMA) systems. A novel SWIPT NOMA protocol is proposed to help the user with the lowest harvested energy by dividing each time slot into mini-slots and adjusting the beamforming of every mini slot to lift the energy level of the lowest energy user under minimum rate constraints. Since the problem is nonconvex, the heuristic scheme is proposed here. Numerical results show that our scheme offers higher harvested energy than that without minislots.