Optimal simultaneous wireless information and energy transfer in OFDMA decode-and-forward relay networks

• Published in: Wireless networks Vol. 23; no. 6; pp. 1731 - 1742
• Main Authors: Huang, Gaofei, Tang, Dong, Zhao, Sai, Qin, Jiayin
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.08.2017; Springer Nature B.V
• Subjects: Communications Engineering; Computer Communication Networks; Decoding; Electrical Engineering; Energy; Energy consumption; Energy harvesting; Energy transfer; Energy transmission; Engineering; Integer programming; IT in Business; Networks; Optimization; Orthogonal Frequency Division Multiplexing; Relay networks; Resource allocation; Subcarriers; Switching theory; Wireless networks; Multiuser diversity; Simultaneous wireless information and energy transfer (SWIET); Relay; Orthogonal frequency division multiple access (OFDMA); Energy harvesting (EH); Resource allocation
• ISSN: 1022-0038; 1572-8196
• DOI: 10.1007/s11276-016-1249-4

In this paper, we consider simultaneous wireless information and energy transfer in an orthogonal-frequency-division-multiple-access decode-and-forward relay network, in which an energy-constrained relay node harvests energy from a source node and uses the harvested energy to forward information to multiple destination nodes. Our objective is to maximize the end-to-end sum rate by resource allocation, subject to transmit power constraint at the source and energy-harvesting (EH) constraint at the relay. A non-convex and mixed-integer programming (MIP) problem is formulated to optimize time-switching (TS) ratios of EH and information decoding at the relay, TS ratio of information transmission from relay to destinations, subcarrier allocation as well as power allocation (PA) over all subcarriers at source and relay. We propose to decouple this problem into a convex problem and an MIP problem in fractional form. To solve the MIP problem, we transform it into an equivalent optimization problem in subtractive form which has a tractable solution. As a result, we propose a novel scheme to achieve jointly optimal TS ratios, subcarrier allocation and PA. Simulation results verify the optimality of our proposed resource allocation scheme.