International Conference Papers
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Item Efficient QoS-aware Heterogeneous Architecture for Energy-Delay Constrained Connected Objects(IFIP, 2016-07-11) Doudou, Messaoud; Rault, Tifenn; Bouabdallah, AbdelmadjidConnected objects such as smart phones and wireless sensors becomes very attractive for our assisted daily life applications, because it offers continuous monitoring capability of both personal and environmental parameters. However, these systems still face a major energy issue that prevent their wide adoption. Indeed, continuous sampling and communication tasks quickly deplete sensors and gateways battery reserves, and frequent battery replacement are not convenient. One solution to address such a challenge consists in minimizing the activation of radio interfaces and switching between them in order to achieve very low duty-cycle. In this paper, we propose a new efficient communication architecture for patient supervision in the context of healthcare application making use of dual radio. At runtime, our solution determines the optimal interval parameters of switching on/off each radio interfaces in order to minimize the energy consumption of both sensors and mobile phones while satisfying the QoS requirements. The proposed solution is adequately analyzed and numerically compared against a solution without QoS. The results show that our proposed architecture exhibits better duty-cycle reduction while satisfying the delay constraints.Item A Study of Wireless Sensor Networks for Urban Traffic Monitoring: Applications and Architectures(Procedia Computer Science, Elsevier, 2013-06-26) Kafi, Mohamed Amine; Challal, Yacine; Djenouri, Djamel; Doudou, Messaoud; Bouabdallah, Abdelmadjid; Badache, NadjibWith the constant increasing of vehicular traffic around the world, especially in urban areas, existing traffic management solutions become inefficient. This can be clearly seen in our life through persistent traffic jam and rising number of accidents. Wireless sensor networks (WSN) based intelligent transportation systems (ITS) have emerged as a cost effective technology that bear a pivotal potential to overcome these difficulties. This technology enables a new broad range of smart city applications around urban sensing including traffic safety, traffic congestion control, road state monitoring, vehicular warning services, and parking management. This manuscript gives a comprehensive review on WSN based ITS solutions. The main contribution of this paper is to classify current WSNs based ITS projects from the application perspective, with discussions on the fulfillment of the application requirements.Item Slotted Contention-Based Energy-Efficient MAC Protocols in Delay-Sensitive Wireless Sensor Networks(2012-07-01) Doudou, Messaoud; Djenouri, Djamel; Badache, Nadjib; Bouabdallah, AbdelmadjidThis paper considers slotted duty-cycled medium access control (MAC) protocols, where sensor nodes periodically and synchronously alternate their operations between active and sleep modes to save energy. Communications can occur only when nodes are in active mode. The synchronous feature makes these protocols more appropriate for delay-sensitive applications than asynchronous protocols. With asynchronous protocols, additional delay is needed for the sender to meet the receiver's active period. This is eliminated with synchronous approaches, where nodes sleep and wake up all together. Moreover, the contention-based feature makes the protocols --considered in this paper-- conceptually distributed and more dynamic compared to TDMA protocols. Duty cycling allows obtaining significant energy saving vs. full duty cycle (sleepless) protocols. However, it may result in significant latency. Forwarding a packet over multiple hops often requires multiple operational cycles (sleep latency), i.e. nodes have to wait for the next cycle to forward data at each hop. Timeliness issues of slotted contention-based MAC protocols are dealt with in this paper, where a comprehensive review and taxonomy is provided. The main contribution is to study and classify the protocols from the delay-efficiency perspective.Item A study of Wireless Sensor Network Architectures and Projects for Traffic Light Monitoring(Elsevier, 2012-08-27) Kafi, Mohamed Amine; Challal, Yacine; Djenouri, Djamel; Bouabdallah, Abdelmadjid; Badache, NadjibVehicular traffic is increasing around the world, especially in urban areas. This increase results in a huge traffic congestion, which has dramatic consequences on economy, human health, and environment. Traditional methods used for traffic management, surveillance and control become inefficient in terms of performance, cost, maintenance, and support, with the increased traffic. Wireless Sensor Networks (WSN) is an emergent technology with an effective potential to overcome these difficulties, and will have a great added value to intelligent transportation systems (ITS) overall. In this survey, we review traffic light projects and solutions. We discuss their architectural and engineering challenges, and shed some light on the future trends as well.