QoS provisioning in Wireless Local Area Network using adaptive admission control and scheduling with priority sliding
Existing Wireless Local Area Networks (WLANs), which are dominated by the IEEE802.11b/a/g/n standards, only provide best effort services. These IEEE802.11 protocols that primarily employ Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) mechanism are unable to provide Quality of Servi...
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| Format: | Thesis |
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2012
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| Summary: | Existing Wireless Local Area Networks (WLANs), which are dominated by the IEEE802.11b/a/g/n standards, only provide best effort services. These IEEE802.11 protocols that primarily employ Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) mechanism are unable to provide Quality of Service (QoS) guarantee to the real time applications. The IEEE802.11e was later introduced to provide prioritized services to the real time applications and protect the real time traffic from the best effort traffic. One major drawback of IEEE802.11e is that it cannot guarantee the stringent QoS required of the real time applications under high traffic load. A solution is needed to provide the prioritized services and control the traffic load, in order to protect the real time applications. In this thesis, a novel Adaptive Priority Sliding Admission Control and Scheduling (APSAS) scheme is proposed on top of the Distributed Coordination Function (DCF) and Enhanced Distributed Channel Access (EDCA) Medium Access Control (MAC) that are commonly used in IEEE802.11b/a/g and IEEE802.11e. APSAS’s roles are generally two folds: (1) controls the number of real time flows admitted to the network and (2) adjusts the priority of selected real time flows in order to accommodate more real time flows without violating the stringent QoS requirements. Extensive simulation studies show that APSAS improves the total throughput, flow throughput ratio, packets end-to-end delay, and jitter of the real time applications over WLAN compared to basic and scheduled DCF/EDCA. The contributions of this thesis are summarized as follow:
• Class Based Queuing (CBQ) is identified as the suitable scheduling scheme for WLAN after extensive simulation verification. Optimal operation point of the admission control scheme is identified.
• Two novel schemes, i.e. Layer 3 Admission Control and Adaptive Scheduling (L3-ACAS) and APSAS that work on top and upgrade the best effort DCF to prove QoS and improve the performance of EDCA are proposed.
• L3-ACAS and APSAS provide a centralized control at router side. |
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