A Slotted Markov Model for EDCA Mechanism in QoS-Aware Industrial IoT Networks: Throughput and Delay Analysis under Saturated Condition

This paper introduces a slotted Markov model to analyze the throughput and access delay distribution of IEEE 802.11e EDCA networks under saturated traffic in Industrial Internet of Things scenarios. Unlike traditional models using variable-duration generic slots, the proposed framework employs fixed backoff slots as foundational units, enabling precise delay analysis. A discrete-time Markov chain (DTMC) integrates multi-dimensional states to capture priority-based QoS mechanisms, backoff stages and countdown, channel occupancy and AIFS differentiation across Access Categories (ACs). The model includes an iterative numerical method for computing steady-state probabilities efficiently. Simulation via NS-3 validates the model’s accuracy by demonstrating the cumulative distribution function (CDF) of access delay. The study addresses the limitations of prior models in handling delay distribution and heterogeneous traffic, offering a robust tool for enhancing IIoT network reliability.