Leila Azouz Saidane

Université de la Manouba, La Manouba, Manouba, Tunisia

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Publications (41)0 Total impact

  • Skander Azzaz, Leila Azouz Saidane
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    ABSTRACT: In this paper, we have introduced three proactive maintenance strategies for static wireless sensor networks (WSNs) using a limited number of mobile maintainer robots: the centralised proactive maintenance strategy denoted by CPMS, the fixed distributed proactive maintenance strategy denoted by FDPMS and the adaptive distributed proactive maintenance strategy denoted by ADPMS. The proposed maintenance strategies are based on a simple energy dissipation analytical model to estimate the occurrence times of the expected sensor failures in the network. Once identified, the anticipated failures are replaced by the available robots before they happen. To select the appropriate maintainer robot for each expected failure, CPMS opts for a centralised scheduling method based on the genetic algorithm fundamentals. However, the distributed maintenance strategies (FDPMS and ADPMS) use two different WSN area partitioning methods to share the sensor maintenance tasks among the available robots. Simulation results have shown that CPMS gives the minimal network dysfunction time representing the interruption service time induced by the detected faulted nodes. However, due to its significant signalling cost, we have remarked that CPMS can be deployed only in small scale WSNs. In large-scale ones, ADPMS has demonstrated its efficiency in terms of the network dysfunction time, the robot travelled distance and the introduced signalling cost. In particular cases, when sensor failures are uniformly distributed on the network map, FDPMS has given the best performances. Copyright © 2013 John Wiley & Sons, Ltd.
    Transactions on Emerging Telecommunications Technologies. 12/2013;
  • Hanen Idoudi, ons mabrouk, leila azouz saidane
    African Journal of Information and Communication Technology. 11/2013; 7(2).
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    ABSTRACT: This paper provides a description of a wireless mesh network testbed setup and a measurement-based performance evaluation of the Optimized Link State Routing (OLSR) protocol [7] under three different routing metrics. The considered metrics include hop-count, ETX and ETT. The network performances are evaluated in an indoor testbed formed by heterogeneous MIMO devices. A part of our tests was about the impact of 802.11n features on the network performances showing the importance of lower layers consideration. Our measurements point out the shortcoming of each metric and eventual optimizations towards a more efficient routing. Experimental results show that OLSR-ETT outperforms OLSR-ETX and OLSR-hopcount significantly in terms of packet loss, end-to-end delay, and efficiency.
    IEEE IWCMC 2013, Italy; 07/2013
  • Hanen Idoudi, Fatma Somaa, Leila Azouz Saidane
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    ABSTRACT: Using wireless body sensors in medical field is becoming an efficient, low cost and non invasive way for continuously monitoring patients' vital signs. New MAC protocols have to be designed to handle the intrinsic constraints of Wireless Body Area Networks (WBANs) especially insuring low latency for alarms management and high reliability. In this paper, we propose a new access method in WBANs for alarms management: E-Health Access Channel Mechanism (E-HACM). E-HACM is intended to be used in e-health applications designed to monitor patients' vital signs by fixing on them body sensors for periodic measurements and to detect critical cases that require real-time delivery and no data loss. Simulation results show that our proposed mechanism outperforms IEEE 802.15.4 in terms of delay, energy consumption and packet loss ratio.
    10th ACS/IEEE International Conference on Computer Systems and Applications (AICCSA); 05/2013
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    ABSTRACT: This paper investigates the design of effective routing metrics in the purpose of network resources optimization and the satisfaction of users QoS requirements. Using several real experiments, we point out the shortcoming of the Expected Transmission Count (ETX) metric for eventual optimizations towards a more efficient routing. Experiments were carried out into an heterogeneous IEEE 802.11n based network running with OLSR routing protocol and have shown that ETX presents several shortcoming resulting in inaccurate estimation of the link quality and then of the routing decision. This paper presents improvements of the ETX metric based on link availibility for accurately finding high-throughput paths in multihop wireless mesh networks.
    10th ACS/IEEE International Conference on Computer Systems and Applications (AICCSA); 05/2013
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    ABSTRACT: Current routing mechanisms proposed for adhocnetworks are still feasibly applied in Wireless Mesh Networks given their similarities. Many researchers have conducted numerous simulations for comparing the performances of these routing protocols under various conditions and constraints. Most made comparisons are not aware of PHY/MAC layers and their impact on routing performances. In this paper we study through simulations the impact of PHY/MAC protocols on higher layers. The considered protocols include three propagation models, i.e., Free Space, TwoRayGround and Shadowing, three different PHY/MAC protocols specified IEEE 802.11 standards namely, 802.11b, 802.11s and 802.11n, and finally three routing protocols, i.e., AODV, OLSR and HWMP. In a comparative way, we investigate the effectiveness of these protocols when they coexist on a wireless mesh network environment. Our results show that the routing strategy can significantly impact the network performance only if it is strongly linked to the characteristics of the lower layers.
    AINA-International Symposium on Frontiers of Information Systems and Network Applications (FINA 2013); 03/2013
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    ABSTRACT: In this paper, we propose a new approach to ensure fault tolerance in wireless sensor networks (WSNs) while guaranteeing both coverage and connectivity in the network. Hence after reviewing the fault tolerance related works in wireless sensor networks and enumerating the requirements that must be satisfied by our fault tolerance solution, we present the different mechanisms we propose to maintain both coverage and connectivity in the network in the case of node failure. Our approach is a proactive one in the sense that it aims to replace the “up to fail” node before its defection. In the case of impossible replacement of the “up to fail” node, a fast rerouting mechanism is proposed to forward the traffic initially routed via the “up to fail” node. Performance evaluation of our fault tolerance approach shows that the number of nodes potentially eligible for the “up to fail” node replacement depends on a threshold about the node redundancy as well as the network density metric. Moreover, we show that, compared to a classical routing algorithm, our fast rerouting mechanism reduces the packet loss rate in the network.
    Wireless Communications and Mobile Computing Conference (IWCMC), 2013 9th International; 01/2013
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    ABSTRACT: In the last few years, femtocells have gained a great deal of interest as an emerging wireless and mobile access technology to improve indoor coverage and network capacity. In such an environment, mobility management is one of the major concerns that may limit the wide deployment and adoption of such networks. In this paper, we investigate the handover procedure for the two-tier macro/femto LTE networks. An optimized handover algorithm with an efficient call admission control has been proposed and described. Our proposed scheme is mainly designed to reduce the number of unnecessary handovers and to maintain the communication quality during the handover. The choice of the femtocell target takes into account the direction of the mobile user, its velocity and the quality of the signal. Performance evaluation results show that our algorithm minimizes both the number of hand-in and the handover drop rate. Besides, the signal quality in terms of SINR after the hand-in is maintained higher than a fixed threshold, which maximizes the sojourn time of the mobile user within the selected femtocell.
    Wireless and Mobile Computing, Networking and Communications (WiMob), 2013 IEEE 9th International Conference on; 01/2013
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    Hanen Idoudi, Chiraz Houaidia, Leila Azouz Saidane, Pascale Minet
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    ABSTRACT: Connectivity and coverage are two crucial problems for wireless sensor networks. Several studies have focused on proposing solutions for improving and adjusting the initial deployment of a wireless sensor network to meet these two criteria. In our work, we propose a new hierarchical architecture for sensor networks that facilitates the gathering of redundancy information of the topology. Several mobile robots must then relocate, in an optimized way, redundant sensors to achieve optimal connectivity and coverage of the network. Mobile robots have to cooperate and coordinate their movement. A performance evaluation is conducted to study the trade-off between the number of required robots and its impact on the rate of network connectivity and coverage.
    Journal of Networking Technology. 03/2012; 3(1):1-12.
  • Skander Azzaz, Leïla Azouz Saïdane, Pascale Minet
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    ABSTRACT: Fault-tolerance is one of the main issues in Wireless Sensor Networks (WSNs) where applications require a continuous service. In this paper, we show how to use a small number of mobile robots to handle failures that may occur in the WSN. We study two strategies: Centralized Manager Strategy (CMS) and CMS with anticipation noted by CMS* to detect, report sensor failures and coordinate the movement of robots. The goal is to minimize the dysfunction time and avoid the coverage and connectivity degradation of the network upon a failure. The CMS is based on the Centralized Manager Algorithm [1] that we improve to ensure that the central manager robot receives a report upon an occurred failure. This manager robot selects a maintainer robot to replace the failed sensor. However, in the CMS* we propose, the manager robot anticipates the sensor failure and reacts before it happens using an energy state model representing the behavior of a sensor based on a discrete time Markov chain.
    Proceedings of the 8th ACM Symposium on Performance evaluation of wireless ad hoc, sensor, and ubiquitous networks, PE-WASUN 2011, Miami Beach, Florida, USA, October 31 - November 4, 2011; 01/2011
  • Chiraz Houaidia, Hanen Idoudi, Leila Azouz Saidane
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    ABSTRACT: Wireless sensor networks are often deployed in hardly accessible or hazardous fields. Their main goal is to monitor the target field and transmit surveillance data to a sink. Therefore, connectivity of the sensor network and the coverage ratio of the monitored area are the most relevant concerns to reach these goals. In this paper, we propose to use several mobile robots to assist sensor networks redeployment in order to enhance the network connectivity and the coverage ratio of the monitored area. We model the sensor network as an islets-based topology and we propose to use robots to detect and heal connectivity and coverage holes availing the sensors redundancy. Preliminary simulations showed that our new scheme can significantly enhance the connectivity ratio of the initial network and improve the coverage ratio by using few numbers of robots.
    01/2011;
  • Inès El Korbi, Leïla Azouz Saïdane
    Proceedings of the 2010 International Conference on Wireless Networks, ICWN 2010, July 12-15, 2010, Las Vegas Nevada, USA, 2 Volumes; 01/2010
  • Ridha Soua, Leila Saidane, Pascale Minet
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    ABSTRACT: An inherent concern for a wireless sensor network(WSN)is the coverage problem. Sensors are usually deployed in the wild to create a network of sensors intended to monitor or control a target area: Sensor networks are assumed unattended in various environments such as disaster areas, hazard fields, or battle fields. However, random node deployment often makes initial sensing holes inside the deployed area inevitable even in an extremely high density network. Furthermore, enhancing coverage is important for sensor networks to provide continuous sensing services. The most challenging aspects of the studies conducted on this topic have been supporting autonomous system with self maintenance capability where sensors and robots work together. This paper proposes to use a mobile robot to assist the initial sensors deployment and to improve sensing coverage and connectivity of monitored area. Given a set of points of interest on the surface, we study how to guide the robot to effectively eliminate coverage holes and collect redundant sensors. We propose a set of heuristics for this problem and we will verify the performance through simulation. The superior coverage and connectivity efficiency of the proposed approach is demonstrated by conducting a comparative analysis and simulation with a greedy approach.
    International Conference on Networking. 01/2010;
  • Cherif Ghazel, Leïla Azouz Saïdane
    JNW. 01/2010; 5:782-791.
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    ABSTRACT: Radio Frequency Identification (RFID) is considered as an emerging technology for the Future Internet called the Internet of Things (IOT). It allows things and objects that embed RFID tags to be identified and to exchange information with each other. However, this new Internet is facing to some problems which are mainly related to the security of information exchange and the integration of RFID tags to the current Internet. The new version of the IETF Host Identity Protocol (HIP) proposed in the Thing to Thing in the Internet of Things project (T2TIT) overcomes the problem of security. Nevertheless, the integration of RFID tags into the IP world is still an open issue. Due to the lack of capacity and resources, these tags can not implement the entire IP stack. To address this issue, we propose in this paper, a new protocol HIP Address Protocol (HAT) that provides network services such as address translation system between the Tag RFID ID and IP addresses, encapsulation/decapsulation, fragmentation/reassembly and object mobility management services. We provide a detailed description of the proposed protocol. We also illustrate through significant scenarios how it operates.
    Proceedings of the International Conference on Wireless and Ubiquitous Systems , ICWUS 2010, October 8-10, 2010, Sousse, Tunesia; 01/2010
  • K. Maalaoui, L. Saidane
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    ABSTRACT: We address analytic performance evaluation of a bluetooth piconet by considering the M/G/1 queue with batch arrivals and vacation times. We present a probabilistic approach to support diverse traffics with QoS guarantees. We consider mainly two constraints: the packet deadline and its priority. We focus on two new scheduling techniques that we have proposed in our previous works. The first technique combines FIFO and the class based priority queuing (PQ) while the second combines EDF (Earliest deadline First) and PQ. We focus our interest to providing Quality of Service (QoS) guarantees to various classes of soft real-time applications by using a probabilistic approach. Here, we compute the end-to-end delay distribution composed by the uplink and downlink waiting times. The end-to-end delay is used to obtain the probability that the response time doesn't exceed a given deadline. Then, we propose a probabilistic admission control procedure for real time flows. We validated the obtained theoretical results through simulations using an extension of the network simulator NS2 called Bluehoc.
    Networking, Architecture, and Storage, 2009. NAS 2009. IEEE International Conference on; 08/2009
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    C. Ghazel, L. Saidane
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    ABSTRACT: In this paper, we propose a set of dimensioning rules, which deliver high quality session-based services over a Next Generation Network based IP/MPLS transport infrastructure. In particular, we develop a detailed dimensioning methodology for improving a target QoS requirement. The proposed methodology outlines an optimal equipment allocation strategy for a requested capacity. The benefits of operating a network under the paradigm of generous dimensioning, for converged multiservice traffic flows, include target QoS guarantee, scalability, and network resilience. We present and discuss experimental results which illustrate a practical implementation of the proposed dimensioning strategy and its benefits.
    Future Generation Communication and Networking, 2008. FGCN '08. Second International Conference on; 01/2009
  • Cherif Ghazel, Leïla Azouz Saïdane
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    ABSTRACT: Satisfying the quality of service (QoS) requirements is one of the main objectives in the design and implementation of IP-based next generation networks (NGN). This paper formalizes an efficient NGN resource-based call admission control (CAC) method which guarantees the QoS requirements expressed in terms of per-service traffic flow throughput, latency, jitter, loss and authorized waiting delay. The proposed method delivers high quality session-based services compliant with the available capacity over an NGN network based IP/MPLS transport infrastructure. The effects of the proposed method on the QoS provision are demonstrated through modeling of the main QoS parameters. Numerical simulations, which illustrate the proposed method benefits in terms of QoS guarantees and transport network scalability, are also presented.
    The Eighth International Conference on Networks, ICN 2009, 1-6 March 2009, Gosier, Guadeloupe, France; 01/2009
  • Cherif Ghazel, Leïla Azouz Saïdane
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    ABSTRACT: Satisfying the quality of service (QoS) requirements is one of the main objectives in the design and implementation of IP-based next generation networks (NGN). This paper formalizes an efficient NGN resource-based call admission control (CAC) method which guarantees the QoS requirements expressed in terms of per-service traffic flow throughput, latency, jitter, loss and authorized waiting delay. The proposed method delivers high quality session-based services compliant with the available capacity over an NGN network based IP/MPLS transport infrastructure. The effects of the proposed method on the QoS provision are demonstrated through modeling of the main QoS parameters. Numerical simulations, which illustrate the proposed method benefits in terms of QoS guarantees and network scalability, are also presented.
    The IEEE 23rd International Conference on Advanced Information Networking and Applications, AINA 2009, Bradford, United Kingdom, May 26-29, 2009; 01/2009
  • Karima Maâlaoui, Leïla Azouz Saïdane
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    ABSTRACT: We address QoS guarantees in a Bluetooth piconet by considering mainly two constraints: the packet deadline and its priority. We evaluate the performances of four intra piconet scheduling schemes: one round robin (1-RR), exhaustive round robin (ERR), limited round robin (LRR) and deficit round robin (DRR), each one combined with our previously proposed local scheduling scheme FP/EDF. We show that DRR gives better performances than the three other schemes. Thus, we propose a new DRR based scheme called PBDRR that takes into consideration the priority of packets. Results have shown that PBDRR performs better than DRR in terms of miss probability.
    Proceedings of the 14th IEEE Symposium on Computers and Communications (ISCC 2009), July 5-8, Sousse, Tunisia; 01/2009