Stefano Lucetti

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The increased popularity and the growth in the number of deployed IEEE 802.11 Access Points (APs) have raised the opportunity to merge together various disjointed wireless LANs to form a unique wireless mesh network (WMN). In this architecture only few nodes, called Portals (MPPs), interface to the external world thanks to their bridging/gateway functions,(More)
The paper proposes an architecture for a scheduling algorithm , to be integrated in IEEE 802.11 Access Points (AP), able to take into account, besides the transport service class required by the destination user, the channel quality experimented by the destination mobile STAtion (STA). The relevance of this topic is due to the observation that when one or(More)
— 802.11 WLANs suffer severe performance degradation as soon as at least one of the stations in the Basic Service Set (BSS) experiments unfavorable radio channel conditions. This degradation is due to a so-called anomaly which manifests when one or some of the stations adopt a reduced transmission data rate, as well as to the reduced efficiency of radio(More)
Wireless systems based on the IEEE 802.11 standard are known to suffer a performance degradation when just a single station in the network experiences bad channel conditions toward the Access Point (AP). This phenomenon, known as the " performance anomaly " , is mainly due to the max-min throughput fairness of the CSMA/CA algorithm of the 802.11 MAC. The(More)
—In the paper we introduce and evaluate the performance of the Deficit Transmission Time (DTT) scheduler, a centralized channel aware scheduling algorithm for IEEE 802.11 networks. The scheduler has been designed to face two inconveniences of 802.11: the performance anomaly and the " inter-flow blocking " problem. DTT splits outgoing frames into multiple(More)
This paper presents a simulation analysis for the evaluation of the admission region of a IEEE 802.11e network adopting the EDCA (Enhanced Distributed Channel Access) mechanism. In particular, this study gives an estimate of the number of QoS-aware applications, namely videoconference and Voice over IP (VoIP), that can be admitted to the transport service(More)
—The recently approved IEEE 802.11e standard improves the support for real-time multimedia applications in Wireless LANs. Yet, to provide some level of guarantee in terms of QoS parameters, it is essential to use an admission control scheme. We have devised one such scheme, which bases the admissibility test on the time occupancy of the medium. The network(More)