Browsing by Author "Younis, Mohamed"

Now showing 1 - 9 of 9
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    Distributed Low-Latency Data Aggregation Scheduling in Wireless Sensor Networks
    (ACM, 2015-04) Bagaa, Miloud; Younis, Mohamed; Djenouri, Djamel; Derhab, Abdelouahid; Badache, Nadjib
    This article considers the data aggregation scheduling problem, where a collision-free schedule is determined in a distributed way to route the aggregated data from all the sensor nodes to the base station within the least time duration. The algorithm proposed in this article (Distributed algorithm for Integrated tree Construction and data Aggregation (DICA)) intertwines the tree formation and node scheduling to reduce the time latency. Furthermore, while forming the aggregation tree, DICA maximizes the available choices for parent selection at every node, where a parent may have the same, lower, or higher hop count to the base station. The correctness of the DICA is formally proven, and upper bounds for time and communication overhead are derived. Its performance is evaluated through simulation and compared with six delay-aware aggregation algorithms. The results show that DICA outperforms competing schemes. The article also presents a general hardware-in-the-loop framework (DAF) for validating data aggregation schemes on Wireless Sensor Networks (WSNs). The framework factors in practical issues such as clock synchronization and the sensor node hardware. DICA is implemented and validated using this framework on a test bed of sensor motes that runs TinyOS 2.x, and it is compared with a distributed protocol (DAS) that is also implemented using the proposed framework.
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    Efficient data aggregation scheduling in wireless sensor networks with multi-channel links
    (ACM, 2013) Bagaa, Miloud; Younis, Mohamed; Badache, Nadjib
    In-network data aggregation is often pursued to remove redundancy and correlate the data en-route to the base-station in order to save energy in wireless sensor networks (WSNs). In this paper, we present a novel cross-layer approach for reducing the latency in disseminating aggregated data to the base-station over multi-frequency radio links. Our approach forms the aggregation tree with the objective of increasing the simultaneity of transmissions and reducing buffering delay. Aggregation nodes are picked and time-slots are allocated to the individual sensors so that the most number of ready nodes can transmit their data without delay. Colliding transmissions are avoided by the use of different radio channels. Our approach is validated through simulation and is shown to outperform previously published schemes.
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    Efficient Multi-Path Data Aggregation Scheduling in Wireless Sensor Networks
    (CERIST, 2013) Bagaa, Miloud; Badache, Nadjib; Ouadjaout, Abdelraouf; Younis, Mohamed
    In wireless sensor networks, in-network data aggregation filters out redundant sensor readings in order to reduce the energy and bandwidth consumed in disseminating the data to the base-station. In this paper, we investigate the problem of reliable collection of aggregated data with minimal latency. The aim is to form an aggregation tree such that there are k disjoint paths from each node to the basestation and find a collision-free schedule for node transmissions so that the aggregated data reaches the base-station in minimal time. We propose a novel algorithm for Reliable and Timely dissemination of Aggregated Data (RTAD). RTAD intertwines the formation of the aggregation tree and the allocation of time slots to nodes, and assigns parents to the individual nodes in order to maximize time slot reuse. The simulation results show that RTAD outperforms competing algorithms in the literature.
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    Improved coverage through area-based localization in wireless sensor networks
    (IEEE, 2013-10) Lasla, Noureddine; Younis, Mohamed; Badache, Nadjib
    Ensuring area coverage is one of the key requirements of wireless sensor networks (WSNs). When nodes are randomly placed in the area of interest, redundancy is often provisioned in order to lower the probability of having voids, where part of the area is not within the detection range of any sensor. To extend the lifetime of the network, a duty cycle mechanism is often applied in which only a subset of the nodes are activated at a certain time while the other nodes switch to low-power mode. The set of active nodes are changed over time in order to balance the load on the individual sensors. The selection of active nodes is subject to meeting the coverage requirement. Assessing the coverage of a sensor is based on knowing its position. However, localization schemes usually yield a margin of errors which diminishes the coverage fidelity. Conservative approaches for mitigating the position inaccuracy assume the worst-case error across the network and end up activating excessive number of nodes and reduces the network lifetime. In this paper, we present an approach for estimating a bound on the maximum error for the position of each sensor and propose a distributed algorithm for achieving high fidelity coverage while engaging only a subset of the sensors. The simulation results confirm the performance advantages of our approach.
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    Intertwined Medium Access Scheduling of Upstream and Downstream Traffic in Wireless Sensor Networks
    (CERIST, 2013-12-25) Bagaa, Miloud; Younis, Mohamed; Djenouri, Djamel; Badache, Nadjib
    In wireless sensor networks, the sensor data are often aggregated en-route to the base-station in order to eliminate redundancy and conserve the network resources. The base-station not only acts as a destination for the upstream data traffic, but it also configures the network by transmit- ting commands downstream to nodes. The data delivery latency is a critical performance metric in time-sensitive applications and is considered by a number of data aggregation schemes in the literature. However, to the best of our knowledge, no solution has considered the scheduling of downstream packets, originated from the base-station, in conjunction with upstream traffic. This paper fills such a gap and proposes MASAUD, which intertwines the medium access schedule of upstream and downstream traffic in order to reuse time slots in a non-conflicting manner and reduce delay. MASAUD can be integrated with any scheme for data aggregation scheduling. The simulation confirms the effectiveness of MASAUD.
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    Intertwined path formation and MAC scheduling for fast delivery of aggregated data in WSN
    (Elsevier, 2014-12-24) Bagaa, Miloud; Younis, Mohamed; Derhab, Abdelouahid; Badache, Nadjib
    This paper studies the problem of data aggregation scheduling in wireless sensor networks (WSNs) to minimize time latency. In prior work on this problem, a node is assigned a parent from the set of unscheduled nodes in order to prevent the creation of cycles. However, using such a strategy reduces the time-slot reuse and consequently has a negative impact on the time latency. To address these shortcomings, we propose IPS (Interwined Path formation and MAC Scheduling) , a novel cross-layer scheme for data aggregation scheduling that allows selecting a parent from all the node’s neighbors including the scheduled ones. IPS achieves reduced data delivery latency through three key design features, namely, (1) intertwining aggregation tree formation and scheduling, (2) for each node, a parent can be selected from already scheduled nodes so that the time latency is reduced and the cycles are prevented and (3) applying parent selection criteria that maximize the time slot reuse. We prove that the data delivery latency for IPS is upper-bounded by , where R is the network radius, Δ is the maximum node degree, and 0.05<∊⩽1. The simulation results show that IPS outperforms seven competing state-of-the-art aggregation scheduling algorithms in terms of latency and network lifetime
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    Multi-Path Multi-Channel Data Aggregation Scheduling in Wireless Sensor Networks
    (Wireless Days, 2013-11-13) Bagaa, Miloud; Younis, Mohamed; Ksentini, Adlen; Badache, Nadjib
    In-network aggregation is employed to cut on re-dundancy and conserve the network resources. To meet the criticality and responsiveness goals, the aggregated data are to be disseminated to the base-station reliably while reducing the delivery latency. In this paper, a novel approach is proposed fo Reliable Multi-channel Scheduling for timely dissemination of Aggregated data (RMSA). RMSA strives to form an aggregation tree such that there are k disjoint paths from each node to the base-station and finds a collision free schedule for node transmissions so that the aggregated data reaches the base-station in minimal time. RMSA is a cross-layer scheme that intertwines the formation of the multi-path structure and the assignment of transmission slots to the individual node with the objective of increasing the simultaneity of transmissions and reducing the buffering delay. The availability of multiple radio channels is further exploited in order to prevent colliding transmissions and boost the overall network throughput. RMSA is validated through simulation and is shown to outperform previously published schemes.
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    On optimal anchor placement for effecient area-based localization in wireless networks
    (IEEE, 2015-06-08) Lasla, Noureddine; Younis, Mohamed; Ouadjaout, Abdelraouf; Badache, Nadjib
    Area-based localization is a simple and efficient approach, where each node estimates its position based on proxim- ity information to some special nodes with known location, called anchors. Based on the anchors’ coordinates, each node first determines its residence area and then approximates its position as the centroid of that area. Therefore, the accu- racy of the estimated position depends on the size of the residence area; the smaller the residence area is, the bet- ter the accuracy is likely to be. Because the size of the residence area mainly depends on the number and the posi- tions of anchor nodes, their deployment should be carefully considered in order to achieve a better accuracy while mini- mizing the cost. For this purpose, in this paper we conduct a theoretical study on anchor placement for a very popular area based localization approach. We determine the optimal anchor placement pattern for increased accuracy and how to achieve a particular accuracy goal with the least anchor count. Our analytical results are further validated through simulation.
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    On optimal anchor placement for effecient area-based localization in wireless networks
    (CERIST, 2015-06-08) Lasla, Noureddine; Younis, Mohamed; Ouadjaout, Abdelraouf; Badache, Nadjib
    Area-based localization is a simple and efficient approach, where each node estimates its position based on proxim- ity information to some special nodes with known location, called anchors. Based on the anchors’ coordinates, each node first determines its residence area and then approximates its position as the centroid of that area. Therefore, the accu- racy of the estimated position depends on the size of the residence area; the smaller the residence area is, the bet- ter the accuracy is likely to be. Because the size of the residence area mainly depends on the number and the posi- tions of anchor nodes, their deployment should be carefully considered in order to achieve a better accuracy while mini- mizing the cost. For this purpose, in this paper we conduct a theoretical study on anchor placement for a very popular area based localization approach. We determine the optimal anchor placement pattern for increased accuracy and how to achieve a particular accuracy goal with the least anchor count. Our analytical results are further validated through simulation.