Performance optimization of IEEE 802.11ax UL OFDMA random access

Abstract

This paper presents an extensive analysis of the IEEE 802.11ax uplink orthogonal frequency-division multiple access (OFDMA)-based random access (UORA) mechanism, addressing inherent inefficiencies in channel access under varying network loads. Specifically, a mathematical model is developed to analyze the system performance of the 802.11ax UORA protocol, enabling the characterization of steady-state operating points under both saturated and unsaturated conditions. Key performance metrics, including system efficiency and mean access delay, are derived as functions of the steady-state operating points. Optimization of these performance metrics through the appropriate selection of backoff parameters is explored, with the analysis validated by simulation results. Additionally, the effects of access parameter heterogeneity, multi-link operation (MLO) and multiple resource unit (MRU) operation capabilities on the performance of IEEE 802.11ax UORA mechanism are further discussed.