Wireless information and power transfer using single and multiple path relays

A relay-based wireless communication model can relay information along with the power bidirectionally using the amplify-and-forward scheme. This paper studies such model extensively. Three information and power relaying protocols, that is, time-based switching relaying, power-based splitting relaying, and hybrid time switching-based and power splitting-based relaying (HTPSR) are used to carry forward bidirectional information and power transfer. First, a solo relay model is studied, for which, we derived a throughput expression for end-to-end information transfer, and this is done for all the three relaying protocols. The paper indicates that the system throughput depends upon the time switching and the power splitting ratio. Further, to make the system more reliable and robust, multiple relays are used in the path. Various relay selection schemes are used for path selection in each transmission, thereby yielding different throughput performances. The results show that an optimal throughput is obtained for a given relay location at an optimal set of values of splitting and switching ratio. Moreover, the HTPSR outperforms both the power splitting and time switching protocol in system throughput performance for a single as well as a multiple-relay model. Whereas, in relay selection schemes, the best SNR selection scheme outperforms in all the schemes used. The simulated results confirm that the system throughput is an active function of relay placement.