Resource allocation for hybrid TS and PS SWIPT in massive MIMO system

Abstract

In this paper, we consider the hybrid time switching (TS) and power splitting (PS) simultaneous wireless information and power transfer (SWIPT) protocol design in massive MIMO system. In this system, the base station (BS) simultaneously serves a set of half-duplex (HD) sensor nodes which are uniformly distributed in its coverage. The whole protocol can be divided into two phases based on the idea of TS. The first phase is designed for sensor nodes energy harvesting as well as downlink training. During this phase, the BS transmits energy signals to the sensor nodes. Based on the idea of PS, the sensor nodes utilize the received energy signals for energy harvesting and downlink channel estimation. In the second phase, the BS schedules the sensors intelligently based on the beam-domain distributions of channels to mitigate interference between sensors and enhance transmission spectral efficiency. Then, the BS forms the receive beamformers for the reception of signals transmitted by sensors. By optimizing transmit powers at the BS and the TS ratio, the system achievable sum rate performance is maximized. Simulation results show the superiority of the proposed protocol on spectral efficiency compared with conventional massive MIMO SWIPT protocol.