An Adaptive Frame-Based Admission Control for Multimedia Traffic in Wireless LAN

Abstract

Improving the performance of delay-constrained video streaming over wireless networks is one of the most important issues for various multimedia-related applications, as well as for the efficient overall utilization of the wireless medium. In this paper, we propose a scheme for adaptive admission control and scheduling for frame-based multimedia traffic in the 802.11 wireless local area networks. The conventional scheduler used for IEEE 802.11e is not suitable for VBR traffic such as MPEG-4 because only a single fixed TXOP is allocated from the hybrid Coordinator. In our scheme, we divide an MPEG flow into three different classes of video-frames depending on the user-QoS, and Our scheme is distributed admission control for each divided video-frame types and poll scheduling adaptive admission control for the flow.

New adaptive frame aggregation call admission control (AFA‐CAC) for high throughput WLANs

“…Z i corresponds to the average transition time of a decrease in a backoff counter for an AC[i]. It depends in a large part on the average deferring time spent in every backoff decreasing attempt while the current channel state is busyK i These two timings are given respectively by (16) and (17).…”

“…The term Pidle i used in (17) represents the probability that an AC[i] senses the channel idle, that is, the channel is not used by another AC or another EDCA station. It is given by (18).…”

“…However these solutions can't provide users satisfaction especially with the increased demands of multimedia applications [15,16]. Hence, an efficient admission control scheme in WLAN is a key to promise the QoS required by real-time and multimedia services [17]. Indeed, the main purpose of an admission control scheme is to limit the amount of traffic admitted into a particular service class in a way to maintain the QoS of the existing flows, while simultaneously the medium resources can be maximally utilised.…”