Study of IEEe 802.11e MAC Based on EDCA and HCCA for QoS Support

Abstract

ProvidingQoSsupport in 802.11WLAN protocols and MAC functions is challengingascurrent 802.11 standard does not takeQoSsupport into account. Both the 802.11 MAC layerand the physical (PHY) layer are designed for best-effort data transmission. With this givenlimitation,thisproject workseeks to achieve comprehensive view of the 802.11e WLAN andcritically analyseQoS limitations and issues in 802.11e WLAN.Thisp tends toevaluate andanalyseQoS techniques and enhancements of MAC layer protocol.The important classes ofQOS guarantee’s which can be used in WLAN are proposed which are differentiation servingsystem, information extracting system based on PHY layer, resource reserving andCAC inMAC layer and IEEE 802.11 parameters tuning system in order to meet the QoSrequirements. However, finding the right set of MAC parameters and the correct QoSmechanisms to use, are still an open issue.Simulations were performed with a scenario withvoice stations, video stations and data stations for both DCF and the EDCF. Comparisonswere made in the aggregated throughput of each traffic type stations.Voice performance andvideo delay performanceweresignificantlyobserved to beimproved via theEDCF.With theobserved delay and error performance, it isexpected that the EDCF can support real-timeapplications with voice and video traffic with a reasonable quality of service in certainenvironments.