  Support of real-time applications that impose strict requirements on packet
loss ratio and latency is an essential feature of the next generation Wi-Fi
networks. Initially introduced in the 802.11ax amendment to the Wi-Fi standard,
uplink OFDMA seems to be a promising solution for supported low-latency data
transmission from the numerous stations to an access point. In this paper, we
study how to allocate OFDMA resources in an 802.11ax network and propose an
algorithm aimed at providing the delay less than one millisecond and
reliability up to 99.999\% as required by numerous real-time applications. We
design a resource allocation algorithm and with extensive simulation, show that
it decreases delays for real-time traffic by orders of magnitude, while the
throughput for non-real-time traffic is reduced insignificantly.
