106,988 research outputs found
IEEE Senior Member
No full textElevazione a grado di "Senior Member" della IEEE (Institute of Electrical and Electronics Engineers) a seguito di nomination da parte di tre figure di livello internazionale (di cui due straniere) e della valutazione da parte del board IEEE su almeno 10 anni di attività lavorativa (attività esclusivamente scientifica in qualità di ricercatore/professore universitario), riconoscendo una performance significativa di almeno 5 anni
"Professor named senior member of IEEE"
No full textNews article"Djamel Bouchaffra, assistant professor in the School of Engineering and Computer Science, has been named a senior member of the Institute of Electrical and Electronics Engineers Inc. (IEEE).
Performance analysis of contention based bandwidth request mechanisms in WiMAX networks
No full textThis article is posted here with the permission of IEEE. The official version can be obtained from the DOI below - Copyright @ 2010 IEEEWiMAX networks have received wide attention as they support high data rate access and amazing ubiquitous connectivity with great quality-of-service (QoS) capabilities. In order to support QoS, bandwidth request (BW-REQ) mechanisms are suggested in the WiMAX standard for resource reservation, in which subscriber stations send BW-REQs to a base station which can grant or reject the requests according to the available radio resources. In this paper we propose a new analytical model for the performance analysis of various contention based bandwidth request mechanisms, including grouping and no-grouping schemes, as suggested in the WiMAX standard. Our analytical model covers both unsaturated and saturated traffic load conditions in both error-free and error-prone wireless channels. The accuracy of this model is verified by various simulation results. Our results show that the grouping mechanism outperforms the no-grouping mechanism when the system load is high, but it is not preferable when the system load is light. The channel noise degrades the performance of both throughput and delay.This work was supported by the U.K. Engineering and Physical Sciences Research Council (EPSRC) under Grant EP/G070350/1 and
by the Brunel University’s BRIEF Award
Performance analysis and enhancements for IEEE 802.11e wireless networks
No full textThis article is posted here with persmission from IEEE - Copyright @ 2005 IEEEThe IEEE 802.11 WLAN legacy standard cannot provide QoS support for multimedia
applications. Thus, considerable research efforts have been carried out to
enhance QoS support for 802.11. Among them, 802.11e is the upcoming QoSenhanced
standard proposed by the IEEE working group. This article describes in
detail the new QoS features of 802.11e based on the latest version of the standard
draft. We investigate the performance of 802.11e through computer simulations.
Using simple examples, we show the effectiveness of adaptive schemes
under the 802.11e framework.This work was supported in part by the French National Telecommunication Research Project (VTHD++) and Science Foundation Ireland WLAN Project (grant no. 03/IN3/I396
Nonlinear filtering for state delayed systems with Markovian switching
No full textCopyright [2003] IEEE. This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.This paper deals with the filtering problem for a general class of nonlinear time-delay systems with Markovian jumping parameters. The nonlinear time-delay stochastic systems may switch from one to the others according to the behavior of a Markov chain. The purpose of the problem addressed is to design a nonlinear full-order filter such that the dynamics of the estimation error is guaranteed to be stochastically exponentially stable in the mean square. Both filter analysis and synthesis problems are investigated. Sufficient conditions are established for the existence of the desired exponential filters, which are expressed in terms of the solutions to a set of linear matrix inequalities (LMIs). The explicit expression of the desired filters is also provided. A simulation example is given to illustrate the design procedures and performances of the proposed method
On the Performance of Interference-Aware Cognitive Ad-Hoc Networks
No full textAbstract-In this paper we analyze the effects of channel availability on channel access delay and service probability of cognitive networks using a modified IEEE 802.11 Media Access Control Protocol (MAC). For the designed cognitive network, cognitive communication is limited by the interference imposed on primary users. We determine the probability of accessing the channel under Rayleigh fading condition for this opportunistic network. We then use this probability to determine the embedded Markov model of the cognitive nodes. We use this Markov model to determine the average channel access delay, and service rate of cognitive nodes. Both simulation and analytical results are presented to access the system performance. Index Terms-Cognitive networks, IEEE 802.11, access delay, service rate
Multipath Routing over Wireless Mesh Networks For Multiple Description Video Transmission
No full textAbstract-In the past few years, wireless mesh networks (WMNs) have drawn significant attention from academia and industry as a fast, easy, and inexpensive solution for broadband wireless access. In WMNs, it is important to support video communications in an efficient way. To address this issue, this paper studies the multipath routing for multiple description (MD) video delivery over IEEE 802.11 based WMN. Specifically, we first design a framework to transmit MD video over WMNs through multiple paths; we then investigate the technical challenges encountered. In our proposed framework, multipath routing relies on the maximally disjoint paths to achieve good traffic engineering performance. However, video applications usually have strict delay requirements, which make it difficult to find multiple qualified paths with the least joints. To overcome this problem, we develop an enhanced version of Guaranteed-Rate (GR) packet scheduling algorithm, namely virtual reserved rate GR (VRR-GR), to shorten the packet delay of video communications in multiservice network environment. Simulation study shows that our proposed approach can reduce the latency of video delivery and achieve desirable traffic engineering performance in multipath routing environment
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