Distributed Delay Estimation and Call Admission Control in IEEE 802.11 WLANs

In recent years VoIP and IEEE 802.11 networks have seen a rapid growth. In IEEE 802.11 networks, an Access Point (AP) and the stations (STAs) it serves form a Basic Service Set (BSS). Each AP can support a limited number of concurrent voice calls; we refer to this number as the AP capacity. After the number of concurrent voice calls in the BSS surpasses the AP capacity, the communication of all users at that AP suffers from high delay, and therefore, poor quality. These are the problems we address with Call Admission Control (CAC). We propose a mobile-station-based CAC mechanism. One of the strengths of the proposed approach is that it is very simple and yet accurate, while not requiring any probing of the medium. Our approach is entirely client-based, thus not requiring any changes in the infrastructure and the protocol.