Saturation throughput analysis of hybrid access mac protocol in ieee 802.11ax wlans

Abstract

Current generation wireless local area networks (WLANs) based on the IEEE 802.11ax standard employ a novel hybrid medium access control (MAC) protocol, which combines contention-based random access (UORA) and contention-free scheduled access (SA) transmissions over orthogonal resource units (RUs). We present a novel fixed-point analysis of the saturation throughput of IEEE 802.11ax that accounts for hybrid access, discrete rate adaptation, and schedulers. Our analysis captures the dynamic flow of users between UORA and SA in hybrid access. The variability in the number of users, which depends on the number of RUs allocated to UORA and the MAC contention protocol, affects the performance of the scheduler. Our approach differs from the literature, which models either UORA or SA (but not both) or assumes a fixed number of SA users. Our results verify the accuracy of the analysis despite its simplicity and reveal that the conventional approaches can overestimate the UORA and SA throughputs.