Performance of NOMA-Based mmWave D2D Networks under Practical System Conditions

This work elaborates the analysis on ergodic capacity, coverage probability, and average throughput for multi-user non-orthogonal multiple access (NOMA) based device-to-device communication networks, which operate in the millimeter-wave spectrum range and are constrained by practical system imperfections such as residual transceiver hardware impairments, imperfect channel state information, and non-ideal successive interference cancellation. More importantly, we consider that the proposed network model is limited by independent and non-identically distributed interference noises emerging from neighboring device nodes. Computationally effective and comprehensive closed-form expressions are delivered to evaluate the ergodic capacity with its upper and lower bounds, as well as coverage probability and average throughput expressions. Furthermore, the asymptotic analysis of ergodic capacity and coverage probability at high and low signal-to-noise-ratio regimes are analyzed and the corresponding closed-form expressions are presented. Valuable discussions on the fairness-based power allocation scheme for NOMA users have been provided. Moreover, a thorough Monte Carlo simulation is carried out to validate the corresponding analytical findings. Finally, simulation results have revealed that the system impairments aforementioned herein cause an ergodic capacity saturation phenomenon. Especially, interference plays a significant role as a performance limitation factor for the ergodic capacity and coverage probability.