Beamforming and Resource Management for Wireless-Powered Communications with Channel Uncertainty

In the era of Internet of Things (IoT), wireless energy transfer (WET) using electromagnetic radiationhas emerged as a potential solution to sustain energy for rechargeable low-powered wireless devices. Ascompared with other near-field WET techniques, the use of radio frequency (RF) signals as a medium iscapable of wirelessly charging devices over a long distance up to several meters. Recently, wireless-poweredcommunications have been proposed for the uplink and downlink applications, namely wireless-poweredcellular networks (WPCN), where wireless devices utilize downlink received power from the base station(BS) for the forthcoming uplink transmission, and simultaneous wireless information and power transfer(SWIPT) systems, where the BS concurrently transmits data and power to wireless devices, respectively. Amajor concern for applying the RF WET in these applications is its low power transfer efficiency due to thesevere wave propagation loss in wireless channels. Multiple-antenna techniques have been introduced torealize efficient WET by synthesizing a sharp energy beam toward an intended receiver. However, theimperfect channel state information (CSI) or limited CSI feedback will also deteriorate the systemperformance. The goal of this project is to address these challenges by considering robust antennabeamforming and resource management for wireless-powered communications with channel uncertainty. Forthe WPCN, we jointly design the beamforming, time allocation and power allocation in both the downlinkand uplink directions by taking into account channel estimation errors. With limited CSI feedback for theSWIPT systems, we jointly optimize the downlink beamforming, downlink transmission and uplink CSIfeedback time ratio, number of feedback bits and power splitting factor. The design objective is to maximizethe system data throughput, and these design problems will be solved by means of convex optimization andMarkov decision process. The impact of massive antennas at the BS on the performance of wireless-poweredcommunications will also be rigorously investigated. Finally, both computer simulation and theoreticalanalysis will be conducted to evaluate the system performance.