Breaking the Barrier to Downlink Packet Capture in OFDMA Wi-Fi Networks

Orthogonal frequency-division multiple access (OFDMA) is considered as one of the main enablers for scaling Wi-Fi throughput. Although the technology was formally introduced with the publication of the IEEE 802.11ax amendment in May 2021, the first commercially available products had already appeared in 2018, and since then millions of access points and client devices have been sold. Still, researchers lack a practical way to observe the OFDMA-based multi-user frame exchanges in the wild. We close this gap by designing and implementing the first open-source complete toolkit that captures every downlink frame of an 802.11ax OFDMA network using only commodity hardware augmented with lightweight firmware patches. An extensive experimental campaign across diverse access points quantifies capture and timing accuracy, error rates, and reveals scheduler behaviors that are opaque to conventional sniffers. By exposing both the capabilities and the limits of COTS-based monitoring, our work provides a foundation for future research on next-generation Wi-Fi MAC protocols and performance tuning.