A characterization of OFDMA uplink activation for industrial applications

This report serves to determine how Orthogonal Frequency Division Multiple Access (OFDMA) is triggered in commercial IEEE 802.11ax (Wi-Fi 6) access points for industrial application scenarios. It presents an overview of OFDMA and how it works in IEEE 802.11ax (Wi-Fi 6). Then, it provides the measurement methodologies for determining OFDMA triggering conditions by performing experiments that vary the traffic, number of wireless stations, and transmitted packet lengths. A wireless sniffer is used to determine when OFDMA trigger frames are sent, indicating OFDMA activation. The resulting table shows what set of conditions activate OFDMA in the test environment. Of the two commercial access points tested in this report, both are observed to follow the same condition for OFDMA activation, namely when two or more stations send over 100 packets per second, regardless of packet size. Another contribution is a method to determine when OFDMA is activated using an industrial computer, configured as a wireless sniffer.