Impact of MU EDCA channel access on IEEE 802.11ax WLANs

To achieve increased radio utilization in dense WLAN deployments, IEEE 802.11ax amendment introduces Orthogonal Frequency Division Multiple Access (OFDMA) to the Wi-Fi standard. As the Access Point (AP) initiates the uplink OFDMA operation via a trigger, this operation provides an additional means for the end-user devices (STAs) to gain medium access. Consequently, to retain fairness in the network and reduce contention, a novel MU EDCA channel access mode has been introduced in 802.11ax standard to temporarily deprioritize medium access for STAs participating in uplink OFDMA operation. In this paper, we implement the key components of 802.11ax OFDMA operation in custom ns-3 network simulator and evaluate the impact of MU EDCA channel access mode on 802.11ax dense WLAN performance under various network and traffic conditions. Our results show that (a) temporarily switching to MU EDCA channel access mode significantly improves network performance in terms of throughput and real-time application latency (b) the duration of temporary switch to MU EDCA channel access mode has negligible impact on network performance and (c) 200 ms of MU EDCA channel access mode can potentially support a dense network of almost 2000 STAs.