In this paper, we study the average throughput performance of energybeamforming in a multi-antenna wireless-powered communication network (WPCN).The considered network consists of one hybrid access-point (AP) with multipleantennas and a single antenna user. The user does not have constant powersupply and thus needs to harvest energy from the signals broadcast by the AP inthe downlink (DL), before sending its data back to the AP with the harvestedenergy in the uplink (UL). We derive closed-form expressions of the averagethroughput and their asymptotic expressions at high SNR for both delay-limitedand delay-tolerant transmission modes. The optimal DL energy harvesting time,which maximizes the system throughput, is then obtained for high SNR. Allanalytical expressions are validated by numerical simulations. The impact ofvarious parameters, such as the AP transmit power, the energy harvesting time,and the number of antennas, on the system throughput is also investigated.
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