International Conference Papers

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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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    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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    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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    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.