Operation Scheme of SWIPT Relay System Based on Interference Energy Harvesting

In wireless relay systems, interference often leads to system rate loss. Recently, the research on radio-frequency signal energy harvesting makes it possible to use interference energy. In this paper, based on the time switching (TS) relay operation strategy and amplify-and-forward protocol, the simultaneous wireless information and power transfer relay system under strong interference is studied. Firstly, we propose an interference energy harvesting (IEH) scheme to reduce the rate loss. Three theorems are proved, and the approximate optimal interference energy allocation factor is obtained. Secondly, we propose two relay operation schemes under strong interference, namely static optimal TS ratio scheme and adaptive optimal TS ratio scheme. Then, the expressions of the two schemes are derived, and the corresponding optimization problems are established. The algorithms for solving these two problems are given. The numerical simulation results show that the IEH schemes with static and adaptive optimal TS ratio can effectively improve the system rate, while the latter has better performance than the former. In addition, the effects of interference power and antenna noise power on the system rate are also studied. The results show that the performance of the two schemes is better than that of the scheme without IEH under different interference power and noise power.