RF Energy Harvesting and Information Transmission based on Power Splitting and NOMA for IoT Relay Systems

Due to the proliferation of the Internet of Things (IoT), an unprecedented expansion of wireless devices and communication among these devices for data transmission is expected over the next few years. IoT devices are rather power constrained and are mostly battery operated devices. Therefore, energy efficiency of such IoT devices or systems is a major concern. In this paper, radio frequency (RF) energy harvesting and information transmission based on Non-orthogonal multiple access (NOMA) protocol is considered for wireless powered IoT relay systems. A source node needs the help of power constrained IoT relay node IoT(R) to transmit its data. IoT(R) node first harvests the energy from the RF signal of the source node and process the information in the first stage and then transmits the source node information data along with its data using NOMA protocol in the next stage. Unlike most of the previous works in this domain, this paper also considers the data transmission of the IoT(R) node along with the source node to its intended destination nodes. Specifically, considering the energy constrained nature of IoT nodes and devices, we have used the combination of power splitting (PS) and NOMA protocol and have mathematically derived the outage probability and sum-throughput for the proposed system. We have also formulated an algorithm to find out the optimal power splitting factor that maximizes the sum-throughput of the proposed system. Our proposed system analytical results are validated by the simulation results.