Adaptive transmission opportunity with admission control for IEEE 802.11e networks

• Authors: Adlen Ksentini;Abdelhak Guéroui;Mohamed Naimi
• Venue: MSWiM '05 Proceedings of the 8th ACM international symposium on Modeling, analysis and simulation of wireless and mobile systems
• Year: 2005

The increase of IEEE 802.11's bandwidth led to a deployment of many multimedia applications over wireless networks. Nevertheless, these applications impose stringent constraints in QoS. In this context, a lot of works have been proposed in order to enhance the QoS-capable IEEE 802.11e MAC protocol. However, they settle for maintaining only an inter-QoS differentiation between the traffic classes, and neglect the intra-Qos differentiation. In fact, the flows belonging to the same service class are assigned the same MAC parameters regardless of their data rate, which leads to throughput fairness rather than perceived QoS fairness. On the other hand, the proposed schemes exhibit performance degradation when the number of flows increases. In this paper, we propose a new MAC protocol based on the reservation of the wireless channel through the use of transmission Opportunity (TXOPlimit) parameter. Each traffic class monitors the MAC queue and computes at runtime the TXOPlimit's value. Thus based on the class' priority and flow's data rate, we can ensure both intra and inter QoS differentiation. Additionally, we specify a distributed admission control mechanism that regulates the network load and protects the admitted flows from the new ones. Simulation results show that compared to the Enhanced Distributed Channel Access (EDCA) scheme of 802.11e, our protocol excels, in terms of network utilization and ability to maintain intra-QoS data rate differentiation. Further when introducing the admission control mechanism, we ensure high protection to the admitted flows, and maintain the network in steady state.