  This letter proposes a control theoretic approach to achieve proportional
fairness amongst access categories (ACs) in an error-prone EDCA WLAN for
provision of distinct QoS requirements and priority parameters. The approach
adaptively adjusts the minimum contention window of each AC to derive the
station attempt probability to its optimum which leads to a proportional fair
allocation of station throughputs. Evaluation results demonstrate that the
proposed control approach has high accuracy performance and fast convergence
speed for general network scenarios.
