Wafa Akkari

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MOO-SNLP: Multi Objectives Optimization for Sensor Network Localization Problem

2019 15th International Wireless Communications & Mobile Computing Conference (IWCMC)

This work highlights the key factors considered to evaluate the performance of a Localization Sys... more This work highlights the key factors considered to evaluate the performance of a Localization System (LS) for W SNs. Indeed, the majority of the existing works concentrated essentially on the accuracy of the estimated location by the LS and ignored its performance in terms of localization cost, scalability and coverage. To address the accuracy/cost trade-off of a LS for WSNs, this work attempted to redefine and reformulate the Sensor Network Localization Problem (SNLP) as a Multi-Objective Optimization Sensor Network Localization Problem (MOO-SNLP). The latter requires the consideration of multiple objectives, like the position accuracy enhancement, with a reduced energy consumption, communication overhead and deployment cost of a localization approach. Moreover, we highlight the performances of the two most commonly-used localization approaches, Recursive Position Estimation (RPE) and Centroid Localization Algorithm (CLA), using different metrics under simulations. In fact, the obtained results show that the trade-off between location accuracy and implementation cost is promising in the area of multi-objective optimization related to SNLP.

LEATCH -L: Low Energy Adaptive Tier Clustering Hierarchy for Large scale WSNs

2018 IEEE/ACM 22nd International Symposium on Distributed Simulation and Real Time Applications (DS-RT), 2018

In recent years, clustering has emerged as a promising approach to facilitate data routing and da... more In recent years, clustering has emerged as a promising approach to facilitate data routing and data aggregation in Wireless Sensor Network (WSN). Although clustering based routing approaches are appropriate for small-scale networks, they do not fit large scale WSNs as it is the case in LEACH [1]. Indeed, clustering suffers from the adverse effects of isolated nodes in the network and some coverage problems. To deal with these issues, we present LEATCH-L, a Low Energy Adaptive Tier Clustering Hierarchy for Large scale WSNs. The proposed approach makes the major functions of LEACH applicable to large-scale WSNs whose dimension is much larger than the largest transmission radius of the sensor nodes. The latter imposes a dynamic decomposable structure on the network topology which results in a set of smaller subnetworks. Such decompositions are implemented through a smart m-level hierarchical clustering process. Moreover, the proposed approach involves a two level data aggregation. Evaluation results show that the introduced approach is scalable with significantly much better performance than the state-of-the art approaches.

An Efficient Recursive Localization Approach for High-Density Wireless Sensor Networks

Semantic Web Science and Real-World Applications, 2019

Although recursive localization approaches are efficiently used in wireless sensor networks (WSNs... more Although recursive localization approaches are efficiently used in wireless sensor networks (WSNs), their application leads to increased energy consumption caused by the important communication overhead necessary to achieve the localization task. Indeed, localization information coverage increases iteratively as new nodes estimate their locations and become themselves new reference nodes. However, the uncontrollable number evolution of such nodes leads, especially in high density networks, to wasted energy, important communication overhead and even impacts the localization accuracy due the adverse effects of error propagation and accumulation. This chapter proposes an efficient recursive localization (ERL) approach that develops a new reliable reference selection strategy to ensure a better distribution of the reference nodes in the network. ERL improves localization accuracy without incurring any additional cost. It allows conserving the energy and consequently prolonging the WSN l...

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Efficient localization approach for large scale wireless sensor networks

2017 13th IEEE International Conference on Intelligent Computer Communication and Processing (ICCP), 2017

To obtain a trade-off between location accuracy and implementation cost, recursive localization s... more To obtain a trade-off between location accuracy and implementation cost, recursive localization schemes are being pursued as a cost-effective alternative to more expensive localization approaches, where localization information increases progressively as new nodes compute their positions and become themselves reference nodes. A strategy is then required to control and maintain the distribution of these new reference nodes. The lack of such a strategy leads, especially in large scale networks, to wasted energy, important communication overhead and even impacts the localization accuracy. In this paper, we propose an efficient recursive localization approach that reduces the energy consumption, the execution time, and the communication overhead, yet it increases the localization accuracy through an adequate distribution of reference nodes within the network.

A Low Overhead Efficient Localization Approach for Large Scale Wireless Sensor Networks

2017 IEEE/ACS 14th International Conference on Computer Systems and Applications (AICCSA), 2017

Although recursive localization approaches stand well in small-scale networks, they are unsuitabl... more Although recursive localization approaches stand well in small-scale networks, they are unsuitable for largescale WSNs. Indeed, they suffer from the adverse effects of error propagation and accumulation. They also require an important communication overhead related to the localization data broadcasted by new reference nodes. To deal with these issues, we developed a new reliable reference selection strategy that ensures a better distribution of these nodes. Our approach couples the novel selection strategy with a refinement phase that enhances the position accuracy. Simulations show that our approach consistently reduces the position error, while it requires less communication overhead. Moreover, it conserves the energy, which helps enhance the WSN lifetime

6th International Conference on Ambient Systems, Networks and Technologies, (ANT 2015) LEATCH: Low Energy Adaptive Tier Clustering Hierarchy

In Wireless Sensor Networks, low latency, energy efficiency, and coverage problems are considered... more In Wireless Sensor Networks, low latency, energy efficiency, and coverage problems are considered as three key issues in designing routing protocols. In this paper we present a new protocol called Low Energy Adaptive Tier Clustering Hierarchy (LEATCH), which offers a good compromise between delay and energy consumption and resolves some coverage problems. For our purpose, a two level hierarchical approach has been proposed to organize a sensor network into a set of clusters, every cluster divided into small clusters that are called Mini Clusters. As the way the clusters are organized, for each mini cluster we define a Mini ClusterHead (MCH). Every MCH communicates with the cluster-head directly, it aggregates its mini-cluster information. In addition, we ha ve made some changes in the procedure of cluster head and mini cluster head election. LEATCH promises better performances than the conventional LEACH protocol which is one of the most known hierarchical routing protocols using th...

Accuracy/Cost Trade-Off in Localization Problem for Wireless Sensor Networks

Self-organization and localization capabilities are among the most important requirements in wire... more Self-organization and localization capabilities are among the most important requirements in wireless sensor networks (WSNs). While existing localization approaches mainly focus on enhancing the accuracy and minimizing the position error, particular attention has recently been given to reducing the localization algorithm implementation cost. This work re-explores the theory of wireless sensor network localization problem (SNLP), which is then re-considered as a multi-objective optimization problem (MOO-SNLP), maximizing the localization accuracy while minimizing the localization cost. The paper discusses a set of evaluation criteria and performance metrics in order to highlight the trade-off between location accuracy and implementation cost such as the energy consumption, communication overhead.

Energy-aware cooperative localization approach for wireless sensor networks

2017 13th IEEE International Conference on Intelligent Computer Communication and Processing (ICCP), 2017

Despite the fact that cooperative localization approaches stand well in Wireless Sensor Networks ... more Despite the fact that cooperative localization approaches stand well in Wireless Sensor Networks (WSNs), they impose challenge of increased energy consumption resulting from the important communication overhead required to accomplish the localization task. In this paper, we developed an Energy Aware Cooperative Localization approach (EACL) based on using a recursive localization system. Obviously, system coverage increases iteratively as nodes with newly-estimated position join the reference set. Our approach implements a novel selection strategy of reference nodes that is beneficial in the sense that: (1) it reduces the adverse effects of error propagation and accumulation, and (2) helps conserve the residual energy of the sensor nodes. Furthermore, we introduced a refinement mechanism to further improve localization accuracy without incurring any additional costs. Simulations showed that our approach consistently reduces the position error. It allows also conserving the energy and...

Power Saving Mechanisms for Ad hoc networks Based on Handshaking Information Tapping

This paper presents an optimization of the functional properties of IEEE 802.11 PSM to improve it... more This paper presents an optimization of the functional properties of IEEE 802.11 PSM to improve its energy conservation without changing or requiring additional control or management frames. PSM relies on a handshaking procedure to announce data traffic before its transmission. This announcement traffic puts a heavy constraint on the sizes of both the ATIM window and the beacon interval and consequently on the network throughput, delay and power saving. All Stations are required to stay awake during the entire ATIM window, and hence they can infer from the already exchanged handshaking frames whether other stations in their vicinities have decided to stay active during the rest of the beacon internal. As such, many announcements could be avoided. First, we present the Neighborhood Aware Power Saving Mechanism (NA-PSM) that reduces the announcement period and hence provides much throughput and power saving than PSM, yet reduces the mean sojourn time of data frames. Second, we present a further refinement of NA-PSM based on the fact that a station having no more traffic to send or receive can power down its tranceiver even though it has already issued an ATIM frame or an ATIM-ACK frame. We show using extensive simulations that the proposed mechanisms outperform clearly PSM in terms of throughput, delay and power saving.

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Low Cost Recursive Localization scheme for High Density Wireless Sensor Networks

International Journal on Semantic Web and Information Systems, 2017

While existing localization approaches mainly focus on enhancing the accuracy, particular attenti... more While existing localization approaches mainly focus on enhancing the accuracy, particular attention has recently been given to reducing the localization algorithm implementation costs. To obtain a tradeoff between location accuracy and implementation cost, recursive localization approaches are being pursued as a cost-effective alternative to the more expensive localization approaches. In the recursive approach, localization information increases progressively as new nodes compute their positions and become themselves reference nodes. A strategy is then required to control and maintain the distribution of these new reference nodes. The lack of such a strategy leads, especially in high density networks, to wasted energy, important communication overhead and even impacts the localization accuracy. In this paper, the authors propose an efficient recursive localization approach that reduces the energy consumption, the execution time, and the communication overhead, yet it increases the l...

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Performance evaluation of power save protocols using carrier sensing in multihop ad hoc networks

2009 IEEE/ACS International Conference on Computer Systems and Applications, 2009

Extending system lifetime by effectively managing power on participating nodes is critical in wir... more Extending system lifetime by effectively managing power on participating nodes is critical in wireless ad hoc networks. Recent work has shown that, by appropriately powering off nodes, energy may be significantly saved. The IEEE 802.11 protocol specifies a simple power save mechanism (PSM) to conserve energy. Data frames are advertised during a fixed period of time, known as an ATIM

LEATCH: Low Energy Adaptive Tier Clustering Hierarchy

Procedia Computer Science, 2015

In Wireless Sensor Networks, low latency, energy efficiency, and coverage problems are considered... more In Wireless Sensor Networks, low latency, energy efficiency, and coverage problems are considered as three key issues in designing routing protocols. In this paper we present a new protocol called Low Energy Adaptive Tier Clustering Hierarchy (LEATCH), which offers a good compromise between delay and energy consumption and resolves some coverage problems. For our purpose, a two level hierarchical approach has been proposed to organize a sensor network into a set of clusters, every cluster divided into small clusters that are called Mini Clusters. As the way the clusters are organized, for each mini cluster we define a Mini Cluster-Head (MCH). Every MCH communicates with the cluster-head directly, it aggregates its mini-cluster information. In addition, we have made some changes in the procedure of cluster head and mini cluster head election. LEATCH promises better performances than the conventional LEACH protocol which is one of the most known hierarchical routing protocols using the probabilistic model to manage the energy consumption in WSNs. Simulation results show that LEATCH performs better than LEACH in term of energy, delay, coverage and scalability.

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Enhancing Power Saving Mechanisms for Ad Hoc Networks Using Neighborhood Information

2008 International Wireless Communications and Mobile Computing Conference, 2008

According to PSM, each station must announce traffic before its transmission. PSM requires for th... more According to PSM, each station must announce traffic before its transmission. PSM requires for this purpose a rather large handshaking period to complete the required announcements. This functional behavior puts a heavy constraint on the size of the announcement period and consequently on throughput, delay and more importantly on power consumption. This paper proposes an optimization of some functional properties of PSM in order to improve its performances. Our proposed UTA-PSM (Unicast Topology Aware Power Saving Mechanism) aims to reduce the number of exchanged announcement frames in order to reduce the announcement period. Conducted simulations show that UTA-PSM outperforms superbly PSM and power saving mechanisms such as the DCS-ATIM that dynamically adjusts the handshaking period according to the traffic load. We show that UTA-PSM delivers more throughput with a smaller average delay yet yielding a much better power saving and robustness.

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Neighborhood aware power saving mechanisms for ad hoc networks

2008 33rd IEEE Conference on Local Computer Networks (LCN), 2008

Resumo: A Filosofia da Ciência ocupa-se com a racionalidade da ciência, mas a ciência tradicional... more Resumo: A Filosofia da Ciência ocupa-se com a racionalidade da ciência, mas a ciência tradicional vai sendo crescentemente substituída pela tecnociência, que implica uma diferente racionalidade, ou seja, uma diferente maneira de justificar seus propósitos e métodos. Neste artigo descrevemos as origens e a evolução histórica da tecnociência e as mudanças que ela introduz na pesquisa científica, particularmente no seu ethos. Essas mudanças deveriam causar uma transformação na Filosofia da Ciência, fazendo com que inclua questões éticas e políticas junto com as epistemológicas, e que trabalhe em cooperação com outros estudos sobre a ciência. Palavras-chave: tecnociência; racionalidade da ciência; Filosofia da Ciência.

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Traffic Aware Power Saving Protocol in Multi-hop Mobile Ad-Hoc Networks

Journal of Networks, 2007

This paper presents an optimization of PSM to improve its energy conservation. According to PSM, ... more This paper presents an optimization of PSM to improve its energy conservation. According to PSM, time is divided into beacon intervals. At the beginning of each beacon interval, all stations must be awake during a specific period called ATIM window to be able to send and receive synchronization messages and announcements of buffered data frames. PSM specifies that a station having sent or received an announcement or having sent a beacon must remain awake during the entire beacon interval. This may lead to wasting energy specially at light traffic loads where stations should conserve the most. We propose an enhancement called the Traffic Aware Power Saving Mode (TA-PSM) to solve this problem by allowing nodes to enter the doze state when they are no more involved in data delivery even if they have already sent a beacon, an ATIM or an ATIM-ACK. Our objective is to reduce the energy consumption without any throttling to throughput. Extensive simulations based on fixed and dynamic topologies showed that TA-PSM provides a much better energy conservation and a lower power consumption per delivered data frame.

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Enhancing Power Saving Mechanisms for Ad hoc

According to PSM, each station must announce traffic before its transmis- sion. PSM requires for ... more According to PSM, each station must announce traffic before its transmis- sion. PSM requires for this purpose a rather large handshaking period to complete the required announcements. This functional behavior puts a heavy constraint on the size of the announcement period and consequently on throughput, delay and more importantly on power consumption. This paper proposes an optimization of some functional properties of PSM in order to improve its performances. Our proposed UTA-PSM (Unicast Topology Aware Power Saving Mechanism) aims to reduce the number of exchanged announcement frames in order to reduce the announcement period. Conducted simulations show that UTA-PSM outperforms superbly PSM and power saving mechanisms such as the DCS-ATIM that dynamically adjusts the handshaking period according to the traffic load. We show that UTA-PSM deliv- ers more throughput with a smaller average delay yet yielding a much better power saving and robustness.

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