Abstract   Nowadays, wireless LANs are widely deployed in various kinds of environment such as home network, public access network and enterprise. The basic standard of wireless LAN, IEEE 802.11 supports only usual Best Effort mode and doesn’t support guaranteed QoS provisioning.
Recently, the IEEE 802.11 working group standardized an enhanced wireless LAN Medium Access Control (MAC) sub-layer, called IEEE 802.11e which supports Quality of Service (QoS). IEEE 802.11e defines Hybrid Coordination Function (HCF) to support differentiated QoS-guaranteed service. HCF consists of two channel access mechanisms, Enhanced Distributed Channel Access (EDCA) and HCF Controlled Channel Access (HCCA). EDCA focuses on prioritized QoS. It provides prioritized QoS among EDCA stations, but does not support strict QoS-guaranteed service. HCCA focuses on parameterized QoS and works using time-bounded scheduling scheme. Thus it can support strict QoS-guaranteed service. For parameterized QoS using HCCA, Traffic Specification (TSPEC) is used for negotiation among Access Point (AP) and stations. TSPEC includes a set of traffic parameters such as maximum service interval, mean data rate, delay bound and nominal MSDU size.
Most of the researches based on QoS provisioning in 802.11e have studied only the case of single hop distance, and did not mention about end-to-end QoS provisioning. In order to provide end-to-end QoS-guaranteed service for realtime applications, such as VoIP and multimedia conferences, both wired and wireless networks require support of QoS provisioning for realtime multimedia service. In wired networking, DiffServ-over-MPLS is one of the solutions used to provide differentiated QoSguaranteed service.
In this paper, the QoS mapping and scheduling of 8 class-types of DiffServ architecture to the access categories of IEEE 802.11e HCCA and EDCA is proposed. The performance of QoS-guaranteed DiffServ provisioning on IEEE 802.11e wireless LAN environment is analyzed. The experimental results show that QoS-guaranteed DiffServ provisioning is possible when the appropriate connection admission control (CAC) is provided.