Performance Analysis of RF Energy Harvesting and Information Transmission Based on NOMA With Interfering Signal for IoT Relay Systems

Owing to the exponential proliferation of the Internet of Things (IoT), it is anticipated that the number of small IoT devices will grow expeditiously over the next few years. These billions of small IoT sensor and devices will consume a huge power for data transmission. In this fashion, radio frequency (RF) energy harvesting has been contemplated as an appealing solution to the architecture of long-term and self-sustainable next-generation wireless systems such as IoT network. However, in the practical environment, such as IoT networks or systems are subjected to external interference factors which often results in the loss of the system rate. In this paper, different from generic RF EH system, where only a source node data is relayed through intermediate EH relaying node, we have considered to transmit the data of IoT relay node along with source node data using non-orthogonal multiple access (NOMA) protocol in the presence of an interfering signal to their respective destinations. Specifically, in the presence on interfering signal, we study the combination of two popular energy harvesting relaying architectures-time switching (TS) relaying and power splitting (PS) relaying with NOMA protocol for IoT relay systems. Considering the interference from the external entity, we have mathematically derived the outage probability, throughput, and sum-throughput for our proposed system. The extensive simulations are carried out to find out the optimal TS and PS factor that maximizes the sum-throughput of the considered system in the presence of an interfering signal. The analytical results of our system model under consideration are validated by the simulation results, and representative performance comparisons are presented.