NIST Industrial Wireless Team Publishes Report on OFDMA Uplink Activation

Karl Montgomery and Rick Candell of the NIST Industrial Wireless Team have produced a report titled “A Characterization of OFDMA Uplink Activation for Industrial Applications” (NIST IR 8506) which presents findings on Orthogonal Frequency-Division Multiple Access (OFDMA) operations based on the IEEE 802.11ax (Wi-Fi 6) specification. OFDMA improves network performance by allowing for simultaneous data transmission from multiple devices. The report details the experimental methodologies and findings used to determine OFDMA triggering conditions. The work examined the conditions required for OFDMA uplink trigger frames sent by commercial access points (APs). In the devices tested, OFDMA was activated when two or more stations transmitted over 100 packets per second (pps), regardless of packet size. This finding was previously not publicly available, as the trigger conditions for OFDMA are not specified in the IEEE 802.11ax (Wi-Fi 6) standard. This finding has led to the recommendation that future Wi-Fi versions implementing OFDMA include a tunable OFDMA trigger condition feature in support of low latency industrial applications.  These recommended modifications to future OFDMA Wi-Fi implementations were recommended to reduce latency for time-critical applications.