Beamformer and time split design for wireless powered multi-antenna cooperative systems

摘要

This paper investigates a three-node cooperative wireless powered communication system consisting of a multi-antenna hybrid access point (H-AP), a single-antenna relay and a single-antenna user. The H-AP first beams energy to the energy constrained relay and user in the downlink and then the relay assists the user using the harvested power for information transmission in the uplink. To maximize the throughput, we investigate the optimal energy beamforming vector and the time split between harvest and cooperation. In addition, suboptimal designs are also studied to reduce the computational complexity, where closed-form expressions are derived for the energy beamforming vector and the time split. Our results show that, the closed-form suboptimal energy beamforming vector and time split yields near optimal performance and implementing multiple antennas at the H-AP can significantly improve the system performance.