Performance Analysis of Energy Beamforming WPCN Links With Channel Estimation Errors

In this paper, we analyze the performance of a wireless-powered communication network that consists of a multiple-antenna hybrid access point (AP) and a single-antenna user. The AP transmits radio frequency (RF) power in the downlink (DL) using maximal ratio transmission (MRT) type energy beamforming. The user harvests it and transmits data to the AP in the uplink (UL), which is received with maximal ratio combining (MRC). Previous analyses have assumed the availability of perfect channel estimation. In contrast, we eliminate this unrealistic assumption and consider the effect of imperfect channel estimates. We first derive the distributions of the received AP signal-to-noise ratio (SNR). We then analyze the average throughput performance of delay-limited and delay-tolerant modes by evaluating the outage probability (OP) and ergodic capacity (EC). We also derive the exact bit error rates (BERs) and symbol error rates (SERs) of several digital modulations. Asymptotic performance expressions in the high SNR regime and the large antenna regime are also developed. Finally, analytical and asymptotic results are validated by Monte-Carlo simulations. The impacts of the transmit power, the energy harvesting (EH) time, the number of antennas and the efficiency of EH are investigated.