A Study of Downlink Power-Domain NOMA Performance in Tactile Internet Employing Sensors and Actuators

The tactile Internet (TI) characterises the transformative paradigm that aims to support real-time control and haptic communication between humans and machines, heavily relying on a dense network of sensors and actuators. Non-orthogonal multiple access (NOMA) is a promising enabler of TI that enhances interactions between sensors and actuators, which are collectively considered as users, thus supports multiple users simultaneously in sharing the same resource block (RB), consequently offering remarkable improvements in spectral efficiency and latency. This article proposes a novel downlink power domain NOMA (PD-NOMA) communication scenario for TI by considering multiple users and a base station. The signal-to-interference noise ratio (SINR), sum rate, and fair power allocation (PA) coefficients are mathematically derived in the NOMA system model. The simulations are performed with two-user and three-user scenarios to evaluate the system performance in terms of bit error rate (BER), sum rate and latency between NOMA and traditional orthogonal multiple access (OMA) schemes. Moreover, outage probability is analysed with varying fixed power allocation (PA) coefficients in the NOMA scheme. Finally, we present the outage probability, sum rate and latency analyses for fixed and derived fair PA coefficients, thus promoting dynamic PA and user fairness by efficiently utilising the available spectrum.