An Energy-Efficient Power Allocation Scheme for NOMA-Based IoT Sensor Networks in 6G

Non-orthogonal multiple access (NOMA) is an upcoming technique to boost the capacity of visible light communication (VLC) systems which is otherwise limited by the slow modulation response of light-emitting diode (LED) sources used therein. We propose to enhance the energy efficiency of NOMA-based VLC systems, thereby making them suitable for green Internet of things (IoT) in the sixth generation (6G) networks. The proposed energy-efficient power allocation (EPA) scheme reduces the average bit error rate (ABER) and augments the system's energy efficiency as well as its capacity and fairness. However, at high values of transmitted power, there is a trade-off between energy efficiency and ABER. We define and evaluate the energy utilization factor to study this trade-off and show that the EPA scheme has superior energy utilization than the state-of-the-art power allocation schemes. Moreover, its performance does not deteriorate appreciably when the number of connected users (or sensor nodes) is increased. Based on numerical and simulation results, we deduce that the proposed EPA scheme meets the requirements of green IoT systems in 6G networks.