Investigation on DL and UL power control in full-duplex systems

In this paper, we focus on the downlink (DL) and uplink (UL) power control issue in a wireless full-duplex system consisting of a full-duplex base station with single antenna and mobile stations working in time-division duplex mode. First, we investigate the signal-to-interference ratios (SIRs) of DL and UL and obtain a formula reflecting their relationship. Then, by employing the Lagrange multiplier method, we derive an optimal joint power control solution to maximize the sum rate of DL and UL channels. Consequently, we propose an efficient switching scheme between the full-duplex mode and the opportunistic half-duplex mode that can be considered as a compensation mode in sum rate maximization. The proposed switching scheme is verified by numerical simulations.