Joint Wireless Information and Energy Transfer in Two-Way Relay Channels

Xiaofeng LING  Rui WANG  Ping WANG  Yu ZHU  

IEICE TRANSACTIONS on Communications   Vol.E101-B   No.6   pp.1476-1484
Publication Date: 2018/06/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2017EBP3206
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
multi-input multi-output (MIMO),  two-way relaying,  Energy harvesting,  convex optimization,  

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In this paper, we study simultaneous wireless information and power transfer (SWIPT) in two-way relay channels where two users exchange information with each other via a multi-antenna relay node. The signals forwarded by the relay node are also used to supply the power to two users. We formulate a max-min optimization problem aiming to maximize the minimum harvested energy between two users to achieve fairness. We jointly optimize the relay beamforming matrix and allocating powers at the two users subject to the quality of service (QoS) constraints. To be specific, we consider the amplify-and-forward (AF) relay strategy and the time splitting SWIPT strategy. To this end, we propose two different time splitting protocols to enable relay to supply power to two users. To solve the non-convex joint optimization problem, we propose to split the original optimization problem into two subproblems and solving them iteratively to obtain the final solution. It is shown that the first subproblem dealing with the beamforming matrix can be optimally solved by using the technique of relaxed semidefinite programming (SDR), and the second subproblem, which deals with the power allocation, can be solved via linear programming. The performance comparison of two schemes as well as the one-way relaying scheme are provided and the effectiveness of the proposed schemes is verified.