Call Admission Control in IEEE 802.11 WLANs Using QP-CAT

As IEEE 802.11 networks in a BSS are increasingly used to carry VoIP, concerns about QoS arise. The overall delay of all VoIP flows drastically increases when the number of VoIP sources approaches the capacity, due to the characteristics of CSMA/CA. We propose a novel call admission control with the Queue size Prediction using Computation of Additional Transmission (QP-CAT) to avoid admitting an excessive number of simultaneous calls. In QP-CAT, an AP can accurately predict the effect of new VoIP flows on the delay of existing VoIP flows by predicting its queue size, before the new VoIP flow is actually admitted. It can be easily extended to support 802.11e so that the AP can predict the effect even when background traffic exists with VoIP traffic under 802.11e.