Hadj Bourdoucen

An adaptive relay nodes selection scheme for multi-hop broadcast in VANETs

Vehicular ad hoc networks (VANETs) have potential applications for improving on-road driving experiences including preemptive road safety measures and provision for infotainment services. This paper proposes a Bi-directional Stable Communication (BDSC) relay nodes selection scheme designed for multi-hop broadcasting protocols over a platoon of vehicles. Relay nodes selection is based on quantitative representation of link qualities for single-hop neighboring nodes by using a proposed link quality estimation algorithm. The BDSC scheme aims to improve packet delivery ratio while maintaining low end-to-end communication delays over a densely populated network with nodes distributed over a large coverage area. To achieve this, the proposed scheme attempts to adaptively balance between the estimated link qualities and the distance between the source broadcaster and the potential forwarders when selecting the next hop nodes for relaying the broadcast messages. Our results from extensive simulation analysis reveal that the proposed BDSC scheme outperforms existing multi-hop broadcasting schemes in terms of packet delivery ratio when evaluated over a densely populated VANETs.

Design of resonant-cavity-enhanced photodetectors using genetic algorithms

Expressions of quantum efficiency of resonant-cavity-enhanced (RCE) PIN photodetectors reported in the literature are based on the assumption of constant reflectivities of the quarter-wave stacks (QWS) at the ends of the cavity. The quantum efficiency is formulated in a closed analytical form that includes the structural parameters of the photodetector and takes into account the wavelength dependence of the reflectivities and the active region absorption coefficient. The variation of the QWS reflectivity and, in particular, its phase constant with wavelength has a significant influence on the resulting quantum efficiency spectra, as demonstrated in this paper. The results are in very good agreement with recently published experimental data which show a dominant peak at the operating wavelength. This behavior has not been predicted by previous simulation results. Since the quantum efficiency spectra are not periodic, the use of the finesse, defined as the ratio of the free spectral range to the full width at half maximum, as a measure of wavelength selectivity is not valid. The conventional quality factor definition used for filter design is thus adopted as a measure of selectivity. A genetic algorithm-based optimization and design procedure for RCE photodetectors have also been developed with the quantum efficiency, quality factor, and frequency bandwidth as input design parameters.

Economic analysis of hybrid power system for rural electrification in Oman

Hybrid renewable energy systems are becoming attractive for remote areas power generation applications due to advances in renewable energy technologies and increase in the oil price. This paper presents a feasibility study of wind penetration into an existing diesel power plant of an isolated Duqum area in the Sultanate of Oman. Wind data from Al Duqm meteorology station and the actual load data from Duqum have been used in the simulation model. HOMER software has been used to perform the study for the hybrid system with no battery storage. For Wind speed less than 5m/s the existing diesel plant seems to be is the only feasible solution over the range of fuel prices used in the simulation. Moreover, the proposed hybrid system becomes feasible at wind speeds of more than 6 m/s and a diesel cost of 0.368 US

Design of ultra-fast dual-wavelength resonant-cavity-enhanced Schottky photodetectors

/L or more, which is the current diesel cost in Duqm.

Optimization procedure for the design of ultrafast, highly efficient and selective resonant cavity enhanced Schottky photodiodes

A systematic optimization procedure for the design of RCE Schottky photodetectors to achieve maximum quantum efficiency and high speed operation at 1.3 and 1.55 /spl mu/m wavelengths is presented. The quantum efficiency formulation used includes the structural parameters of the photodetector and takes into account the wavelength dependence of the top and bottom mirrors reflectivities. The results have shown that the value of the thickness of the antireflection coating layer has a major influence in selecting the width of the photodetector to simultaneously achieve maximum quantum efficiency and high bandwidth at the two wavelengths. Simulated values of 270 and 40 GHz were obtained, respectively, for the 3-dB carrier-transit time-limited bandwidth and bandwidth-efficiency product for an RCE Schottky photodetector with a 0.02-/spl mu/m gold layer.

Network control and engineering for Qos, security and mobility II

An expression of quantum efficiency for high-speed resonant-cavity-enhanced (RCE) Schottky photodiodes is derived. This expression includes the structural and the physical parameters of the photodetector and takes into account the parameters of the metallic Schottky mirror and the wavelength dependence of the reflectivities. The metal layer thickness sets the maximum achievable quantum efficiency as it decays exponentially with it. The antireflection coating layer, on the other hand, determines the photodetector selectivity and the optimum absorption layer thickness that maximizes its quantum efficiency. An algorithm for the design and optimization of RCE Schottky photodetectors has been developed. Theoretical values of 647 GHz and 129 GHz were obtained, respectively, for the carrier-transit time limited 3-dB bandwidth and bandwidth-efficiency product for an RCE Schottky photodetector with a 0.02 /spl mu/m gold layer.

Performance impact of relay cardinality on sender-driven messages dissemination in VANETs

Preface. 1. A Scalable Multicast Protocol With Qos Guaranties A. Benslimane, O. Mouassaoui. 2. Scheduling Requests On Multi-Stage Multi-Server To Increase Quality Of Service A. Allahverdi, F.S. Al-Anzi. 3. Analysis Of Policy Management Models And Specification Languages I. Aib, N. Agoulmine, M. Fonseca, G. Pujolle. 4. Diffserv Network Control Using A Behavioral Multi-Agent System N. Meskaoui, L. Merghem, D. Gaiti, K.Y. Kablan. 5. Policy Based Handover In Wireless And Mobile Networks H. Chaouchi. 6. Adaptive AIFS In Wireless LAN A. Ksentini, A. Gueroui, M. Naim. 7. Teletraffic Engineering Of Multi-Band W-CDMA Systems V.B. Iversen, E. Epifania. 8. Mobility Support Framework In Adaptable Service Architecture M. Malek Shiaa. 9. Ant-Routing-Algorithm For Mobile Multi-Hop Ad-Hoc Networks M. Gunes, O. Spaniol. 10. Enabling Distributed Qos Management Utilizing Active Network Technology S. Vrontis, I. Sygkouna, M. Chantzara, E. Sykas. 11. Resource Management In ASMA Platform H. Bakour, N. Boukhatem. 12. A New Hardware Algorithm For Fast IP Routing Targeting Programmable Routers M. Meribout, M. Motomura. 13. Fuzzy-Logic-Based TCP Congestion Control System A.M. Al-Naamany, H. Bourdoucen. 14. Multi-Object Video Rate Control N. Achir, G. Pujolle. 15. Buffer Occupancy Analysis For A Broadband Polling-Based WLAN A.S.H. Mahmoud, D.D. Falconer, S.A. Mahmoud. 16. A Policy Management Framework For GMPLS Optical Networks N. Rico, O.Cherkaoui, H. Elbiaze. 17. Service Level Agreement In Optical Networks M. Du-Pond, O. Audouin, B. Berde, B. Daheb, W. Fawaz, G. Pujolle, M. Vigoureux. 18. Conceptual Foundations Of User Preference Modeling Z. Chentouf, A. Khoums, S. Cherkaoui. 19. New Key Management Protocol For SSL/TLS I. Hajjeh, A. Serhrouchni, F. Tastet. 20. Management Of Security In TCP/IP Hosts Using Dedicated Monitoring Applications R. Costa Cardoso, M. Marques Freire.

TCP Congestion Control Approach for Improving Network Services

Wireless communication protocols based on vehicular ad hoc networks (VANETs) have potential applications for improving on-road experiences including road safety. This work investigates relay cardinality impact on the performance of sender-driven multi-hop messaging protocols over VANETs. The aim of this study is to identify suitable relay set cardinalities for varying spectrum of applications, with emphasis on active alert messaging protocols. Impact of relay cardinality is evaluated while considering end-to-end communication delays and reachability of messages as performance measurement metrics. Performance evaluation is conducted for broadcast messages over large coverage and densely populated networks. Simulation experiments reveal that reachability of the sender-driven broadcasts improve to a certain extend with increase in relay cardinality, but at the expense of increasing end-to-end delays.

Improving reachability of multi-hop alert messages dissemination in VANETs

With the continuous increasing demand of Internet applications, networks are experiencing a serious congestion problem. This affects directly the networks’ services and management due to large amounts of data loss and long transmission delays. The present work suggests an improved networking congestion control approach for TCP using fuzzy logic. Its main objective is to use packet drop information to improve network services by optimizing data throughput and smoothing data transfer profiles.

Relay selection for alert messaging in vanets based on bi-directional stable communication approach

Alert messaging protocols based on vehicular ad hoc networks (VANETs) are speculated as promising on-board applications for improving road safety. This work presents a novel alert broadcasting protocol based on estimated link qualities. Link quality estimations are based on the proposed Bi-Directional Stable Communication (BDSC) protocol which aims at achieving high reachability of alert messages. The new protocol makes better selection of relay nodes during multi-hop broadcasts, resulting in reachability improvement of alert messages over a platoon of vehicles. Simulation experiments reveal that in dense traffic scenarios, reachability of the proposed BDSC protocol outperforms the conventional furthest distance based relay selection protocols by more than 20%.