On the Error Floor Evaluation of NOMA-Irregular Repetition Slotted ALOHA

In this work, we provide a simple yet tight analytical approximation of the packet loss rate in the error floor region for a non-orthogonal multiple access (NOMA)-based irregular repetition slotted ALOHA (IRSA) scheme. Considering an Internet of Things (IoT) scenario, users randomly select both the number of replicas based on a designed degree distribution and the transmission power from predetermined levels, while successive interference cancellation (SIC) is performed at the receiver. Our derived packet loss rate expression in the finite length regime is promptly evaluated. Its accuracy is validated through Monte-Carlo simulations, demonstrating a strong match across channel loads, including those beyond the low load regime