Optimization and analysis of wireless powered multi-antenna cooperative systems
journal contributionposted on 27.07.2017, 16:00 by Han Liang, Caijun Zhong, Himal A. Suraweera, Gan Zheng, Zhaoyang Zhang
In this paper, we consider a three-node cooperative wireless powered communication system consisting of a multi-antenna hybrid access point (H-AP) and a single-antenna relay and a single-antenna user. The energy constrained relay and user first harvest energy in the downlink and then the relay assists the user using the harvested power for information transmission in the uplink. The optimal energy beamforming vector and the time split between harvest and cooperation are investigated. To reduce the computational complexity, suboptimal designs are also studied, where closed-form expressions are derived for the energy beamforming vector and the time split. For comparison purposes, we also present a detailed performance analysis in terms of the achievable outage probability and the average throughput of an intuitive energy beamforming scheme, where the H-AP directs all the energy towards the user. The findings of the paper suggest that implementing multiple antennas at the H-AP can significantly improve the system performance, and the closed-form suboptimal energy beamforming vector and time split yields near optimal performance. Also, for the intuitive beamforming scheme, a diversity order of N+1/2 can be achieved, where N is the number of antennas at the H-AP.
This work was supported in part by the National Natural Science Foundation of China under Grant 61671406, in part by the Zhejiang Provincial Natural Science Foundation of China under Grant LR15F010001, and in part by the Opening Project of Key Laboratory of Cognitive Radio and Information Processing through the Ministry of Education (Guilin University of Electronic Technology) under Grant CRKL160201. The work of G. Zheng was supported by UK EPSRC under Grant EP/N007840/1.
- Mechanical, Electrical and Manufacturing Engineering