International Journal Papers

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Subject: search.filters.subject.End-to-End Delay

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    Delay-efficient MAC protocol with traffic differentiation and run-time parameter adaptation for energy-constrained wireless sensor networks
    (Springer, 2016-02) Doudou, Messaoud; Djenouri, Djamel; M. Barcelo-Ordinas, Jose; Badache, Nadjib
    This paper presents an asynchronous cascading wake-up MAC protocol for heterogeneous traffic gathering in low-power wireless sensor networks. It jointly considers energy/delay optimization and switches between two modes, according to the traffic type and delay requirements. The first mode is high duty cycle, where energy is traded-off for a reduced latency in presence of realtime traffic (RT). The second mode is low duty cycle, which is used for non-realtime traffic and gives more priority to energy saving. The proposed protocol, DuoMAC, has many features. First, it quietly adjusts the wake-up of a node according to (1) its parent’s wake-up time and, (2) its estimated load. Second, it incorporates a service differentiation through an improved contention window adaptation to meet delay requirements. A comprehensive analysis is provided in the paper to investigate the effectiveness of the proposed protocol in comparison with some state-of-the-art energy-delay efficient duty-cycled MAC protocols, namely DMAC, LL-MAC, and Diff-MAC. The network lifetime and the maximum end-to-end packet latency are adequately modeled, and numerically analyzed. The results show that LL-MAC has the best performance in terms of energy saving, while DuoMAC outperforms all the protocols in terms of delay reduction. To balance the delay/energy objectives, a runtime parameter adaptation mechanism has been integrated to DuoMAC. The mechanism relies on a constrained optimization problem with energy minimization in the objective function, constrained by the delay required for RT. The proposed protocol has been implemented on real motes using MicaZ and TinyOS. Experimental results show that the protocol clearly outperforms LL-MAC in terms of latency reduction, and more importantly, that the runtime parameter adaptation provides additional reduction of the latency while further decreasing the energy cost.
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    Performance Optimization of Duty-Cycled MAC in Delay-Energy Constrained Sensor Network Under Uniform and Non-Uniform Traffic Generation
    (interscience.wiley, 2016) Doudou, Messaoud; M. Barcelo-Ordinas, Jose; Djenouri, Djamel; Badache, Nadjib; Garcia-Vidal, Jorge
    Duty-Cycle at the MAC layer plays a key role in energy savings and network lifetime extension. It consists in putting a node’s radio in the sleep state as soon as it has no communication activity. Traditional WSN MAC protocols are designed with short duty cycles at the cost of long delays. Careful design is required for joint energy-delay constrained applications, where the optimal parameters should be thoroughly derived. The present paper deals with this issue and mathematically derives optimal values of key MAC parameters under low data rate applications for three well known duty-cycled MAC protocols, WiseMAC, SCP-MAC, and LMAC as representatives of three MAC protocol categories, respectively preamble-sampling, slotted contention-based and frame-based. The analysis provides also the optimum traffic sampling rate that guarantees the minimum energy consumption. It shows the role of these parameters in achieving the targeted e2e (end-to-end) delay constraints under network models with uniform traffic generation, for ring and grid topologies. As a second contribution, the model is extended to non-uniform traffic scenarios, where a certain percentage of deployed nodes are relays whose role is to balance traffic forwarding and save the overall network energy. The results reveal that different optimal internal MAC parameters and traffic generation rates can be found for different configurations of relay nodes deployment, which achieve minimal network energy consumption while satisfying the application required e2e delay threshold
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    Game Theory Framework for MAC Parameter Optimization in Energy-Delay Constrained Sensor Networks
    (ACM, 2016-05-15) Doudou, Messaoud; M. Barcelo-Ordinas, Jose; Djenouri, Djamel; Garcia-Vidal, Jorge; Bouabdallah, Abdelmadjid; Badache, Nadjib
    Optimizing energy consumption and end-to-end (e2e) packet delay in energy-constrained, delay-sensitive wireless sensor networks is a conflicting multi-objective optimization problem. We investigate the problem from a game theory perspective, where the two optimization objectives are considered as game players. The cost model of each player is mapped through a generalized optimization framework onto protocol specific MAC parameters. From the optimization framework, a game is first defined by the Nash Bargaining Solution (NBS) to assure energy-consumption and e2e delay balancing. Secondly, the Kalai-Smorodinsky Bargaining Solution (KSBS) is used to find equal proportion of gain between players. Both methods offer a bargaining solution to the duty-cycle MAC protocol under different axioms. As a result, given the two performance requirements, i.e., the maximum latency tolerated by the application and the initial energy budget of nodes, the proposed framework allows to set tunable system parameters to reach a fair equilibrium point which dually minimizes the system latency and energy consumption. For illustration, this formulation is applied to six state-of-the-art Wireless Sensor Network (WSN) MAC protocols; B-MAC, X-MAC, RI-MAC, SMAC, DMAC, and LMAC. The paper shows the effectiveness and scalability of such framework in optimizing protocol parameters that achieve a fair energy-delay performance trade-off under the application requirements.