  In order to meet the ever-increasing demand for high throughput in WiFi
networks, the IEEE 802.11ax (11ax) standard introduces orthogonal frequency
division multiple access (OFDMA). In this letter, we address the
station-resource unit scheduling problem in downlink OFDMA of 11ax subject to
minimum throughput requirements. To deal with the infeasible instances of the
constrained problem, we propose a novel scheduling policy based on weighted
max-min fairness, which maximizes the minimum fraction between the achievable
and minimum required throughputs. Thus, the proposed policy has a well-defined
behavior even when the throughput constraints cannot be fulfilled. Numerical
results showcase the merits of our approach over the popular proportional
fairness and constrained sum-rate maximization strategies.
