Joint Time Allocation for Wireless Energy Harvesting Decode-and-Forward Relay-Based IoT Networks With Rechargeable and Nonrechargeable Batteries

This article considers a one-way decode-and-forward (DF) relay-based Internet-of-Things (IoT) network consisting of a source, a relay, and a destination in wireless energy harvesting (EH) and information transmission (IT) using the time switching-based relaying (TSR) protocol. The one-way DF relay network using the TSR protocol consists of some time slots. This article proposes the time allocation scheme for maximizing the achievable data rate under the total block time constraint. It is assumed that the relay is considered the IoT device used for long periods of time without battery replacement and it is equipped with both nonrechargeable and rechargeable batteries. Based on the supplied power by the nonrechargeable battery, the proposed scheme determines whether or not to harvest energy and operates two alternate time allocation schemes. Since the proposed scheme is based on the closed-form expressions, it provides low complexity. Numerical results show that the achievable data rate of the proposed time allocation scheme is greater than that of the fixed time allocation scheme.