International Journal Papers

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    Energy-Aware Constrained Relay Node Deployment for Sustainable Wireless Sensor Networks
    (IEEE, 2017-03) Djenouri, Djamel; Bagaa, Miloud
    This paper considers the problem of communication coverage for sustainable data forwarding in wireless sensor networks, where an energy-aware deployment model of relay nodes (RNs) is proposed. The model used in this paper considers constrained placement and is different from the existing one-tiered and two-tiered models. It supposes two different types of sensor nodes to be deployed, i) energy rich nodes (ERNs), and ii) energy limited nodes (ELNs). The aim is thus to use only the ERNs for relaying packets, while ELN’s use will be limited to sensing and transmitting their own readings. A minimum number of RNs is added if necessary to help ELNs. This intuitively ensures sustainable coverage and prolongs the network lifetime. The problem is reduced to the traditional problem of minimum weighted connected dominating set (MWCDS) in a vertex weighted graph. It is then solved by taking advantage of the simple form of the weight function, both when deriving exact and approximate solutions. Optimal solution is derived using integer linear programming (ILP), and a heuristic is given for the approximate solution. Upper bounds for the approximation of the heuristic (versus the optimal solution) and for its runtime are formally derived. The proposed model and solutions are also evaluated by simulation. The proposed model is compared with the one-tiered and two-tiered models when using similar solution to determine RNs positions, i.e., minimum connected dominating set (MCDS) calculation. Results demonstrate the proposed model considerably improves the network life time compared to the one-tiered model, and this by adding a lower number of RNs compared to the two-tiered model. Further, both the heuristic and the ILP for the MWCDS are evaluated and compared with a state-of-the-art algorithm. The results show the proposed heuristic has runtime close to the ILP while clearly reducing the runtime compared to both ILP and existing heuristics. The results also demonstrate scalability of the proposed solution.
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    Synchronization Protocols and Implementation Issues in Wireless Sensor Networks: A Review
    (IEEE, 2015) Djenouri, Djamel; Bagaa, Miloud
    Time synchronization in wireless sensor networks (WSNs) is a topic that has been attracting the research community in the last decade. Most performance evaluations of the proposed solutions have been limited to theoretical analysis and simulation. They consequently ignored several practical aspects, e.g., packet handling jitters, clock drifting, packet loss, and mote limitations, which affect real implementation on sensor motes. Authors of some pragmatic solutions followed empirical approaches for the evaluation, where the proposed solutions have been implemented on real motes and evaluated in testbed experiments. This paper gives an insight on issues related to the implementation of synchronization protocols in WSN. The challenges related to WSN environment are presented; the importance of real implementation and testbed evaluation are motivated by some experiments we conducted. The most relevant implementations of the literature are then reviewed, discussed, and qualitatively compared. While there are several survey papers that present and compare the protocols from the conception perspectives, as well as others that deal with mathematical and signal processing issues of the estimators, a survey on practical aspects related to the implementation is missing. To our knowledge, this paper is the first one that takes into account the practical aspect of existing solutions.
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    New power-aware routing for mobile ad hoc networks
    (Inderscience, 2006) Djenouri, Djamel; Badache, Nadjib
    Since devices used in wireless mobile ad hoc networks are generally supplied with limited autonomous resources, energy conservation is one of the most significant aspects in these networks. Recent studies show that the energy consumed for routing data-packets in mobile ad hoc networks can be significantly reduced compared with the min-hop full-power routing protocols. One of the promising mechanisms proposed in literature to reduce the energy consumption is the transmission power control. In this paper, we define new routing metrics to strike a balance between the required power minimisation and batteries freshness consideration. We also define a new technique which allows the distribution of the routing task over nodes. Using these metrics and techniques we derive from DSR [2] a new power-aware and power-efficient routing protocol, whose performance is analysed by simulation in different situations of mobility and network load.
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    Ad hoc networks routing protocols and mobility
    (2006-04) Djenouri, Djamel; Derhab, Abdelouahid; Badache, Nadjib
    An ad hoc network is a temporary infrastructureless network, formed dynamically by mobile devices without turning to any existing centralized administration. To send packets to remote nodes, a node uses other intermediate nodes as relays, and ask them to forward its packets. For this purpose, a distributed routing protocol is required. Because the devices used are mobile, the network topology is unpredictable, and it may change at any time. These topology changes along with other intrinsic features related to mobile devices, such as the energy resource limitation, make ad hoc networks challenging to implement efficient routing protocols. In this paper, we drive a GloMoSim based simulation study, to investigate the mobility effects on the performance of several mobile ad hoc routing protocols.