III Mohsin Hameed Fachhochschule Lippe und Höxter SS 2007 Abstract The advantages of using IEEE 802.11-based Wireless Local Area Networks (WLAN) in industrial automation applications are substantial and include: mobility, ease and speed of installation, flexibility and costs. But wireless applications for industrial automation applications have rigorous requirements on quality of service (QoS) ...

Large-scale deployment of IEEE 802.11 wireless LANs (WLANs) with a high density of access points (APs) has become commonplace due mainly to its potential for numerous benefits, such as ubiquitous service coverage, seamless handover, and improved link quality. However, the increased AP density can induce significant channel contention among neighboring cells, thus causing severe performance degr...

Multihop, ad-hoc Wireless Local Area Networks (WLAN) based on 802.11 are expected to serve as important segments of next generation wireless networks. In the network layer of intermediate nodes of such networks, a priority scheduler arbitrates the transmission between forwarding traffic and the node’s own locally produced traffic. Meanwhile, a new QoS-aware Enhanced Distributed Channel Access (...

We present the station-based unfair access problem among the uplink and the downlink stations in the IEEE 802.11e infrastructure Basic Service Set (BSS) when the default settings of the Enhanced Distributed Channel Access (EDCA) parameters are used. We discuss how the transport layer protocol characteristics alleviate the unfairness problem. We design a simple, practical, and standard-compliant...

In Wireless Local Area Networks (WLANs), the unpredictable injection of traffic load and the limitations of DCF based bandwidth allocation may result in network congestion. Also the Quality of Service (QoS) of data flows with different priorities may not be strictly guaranteed. In order to support service differentiation and guarantee QoS of data transmission over WLANs, based on the extended L...

As wireless LANs are gaining popularity, the demand for supporting multimedia and QoS-sensitive applications becomes more important than before. Although enhancements to the legacy IEEE 802.11 MAC to support QoS mechanisms have been proposed, they suffer from unfair allocation of bandwidth between high and low priority traffic. We propose a distributed enhanced fair scheduling (EFS) scheme that...

The majority of analytical work on the performance of IEEE 802.11 [1] focuses on predicting the throughput and the mean delay of only the medium access, although higher layer applications and protocols are interested in the total performance of the MAC layer. Seen in this perspective, surprisingly little focus has been on predicting the queueing delay. The main contribution of this paper oppose...