Feedback Based Distributed Admission Control in 802.11 WLANs
A distributed Connection Admission Control (CAC) scheme where stations independently admit or reject flows based on channel utilization threshold is easy to implement for WLANs. However, owing to variable protocol capacity, the advisable threshold also is variable, limiting the efficacy of fixed threshold based CAC. If the admission threshold is tuned to reflect the current protocol capacity, better throughput can be obtained while avoiding WLAN overload. In this paper, the authors propose a feedback based scheme to tune the utilization threshold for admission. They select the performance metric used for feedback, derive the system model from empirical data, and use control theory to design a feedback controller.