  This paper studies optimal resource allocation in the wireless-powered
communication network (WPCN), where one hybrid access-point (H-AP) operating in
full-duplex (FD) broadcasts wireless energy to a set of distributed users in
the downlink (DL) and at the same time receives independent information from
the users via time-division-multiple-access (TDMA) in the uplink (UL). We
design an efficient protocol to support simultaneous wireless energy transfer
(WET) in the DL and wireless information transmission (WIT) in the UL for the
proposed FD-WPCN. We jointly optimize the time allocations to the H-AP for DL
WET and different users for UL WIT as well as the transmit power allocations
over time at the H-AP to maximize the users' weighted sum-rate of UL
information transmission with harvested energy. We consider both the cases with
perfect and imperfect self-interference cancellation (SIC) at the H-AP, for
which we obtain optimal and suboptimal time and power allocation solutions,
respectively. Furthermore, we consider the half-duplex (HD) WPCN as a baseline
scheme and derive its optimal resource allocation solution. Simulation results
show that the FD-WPCN outperforms HD-WPCN when effective SIC can be implemented
and more stringent peak power constraint is applied at the H-AP.
