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Author: search.filters.author.Badache, NadjibSubject: search.filters.subject.Wireless Sensor Networks

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    Cost Effective Node Deployment Strategy for Energy-Balanced and Delay-Efficient Data Collection in Wireless Sensor Networks
    (CERIST, 2014-01-08) Doudou, Messaoud; Djenouri, Djamel; M. Barcelo-Ordinas, Jose; Badache, Nadjib
    The real-world node deployment aspect is investigated, while considering cost minimization for resolving the energy hole around the sink, which represents a serious problem in typical sensor networks with uniform distribution. A novel strategy is proposed that is based on the use of two sinks and a few extra relay nodes close to the sinks’ areas. The traffic is then alternatively sent to the sinks in every other cycle. As a second contribution, an efficient data collection mechanism has been developed to determine the optimal data rate that meets delay requirements of individual sensor reports and improves the network lifetime. The comparison of the proposed node deployment strategy with uniform, non-uniform geometric and linear increase node distributions demonstrates that the cost of the proposed solution is very close to that of the uniform distribution and much lower than all the others, while achieving a load balancing at the same order of the state-of-the-art solutions perspective.
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    Survey on Latency Issues of Asynchronous MAC Protocols in Delay-Sensitive Wireless Sensor Networks
    (CERIST, 2012) Doudou, Messaoud; Badache, Nadjib; Djenouri, Djamel
    Energy-efficiency is the main concern in most Wireless Sensor Network (WSN) applications. For this purpose, current WSN MAC (Medium Access Control) protocols use duty-cycling schemes, where they consciously switch a node’s radio between active and sleep modes. However, a node needs to be aware of (or at least use some mechanism to meet) its neighbors’ sleep/active schedules, since messages cannot be exchanged unless both the transmitter and the receiver are awake. Asynchronous duty-cycling schemes have the advantage over synchronous ones to eliminating the need of clock synchronization, and to be conceptually distributed and more dynamic. However, the communicating nodes are prone to spend more time waiting for the active period of each other, which inevitably influences the one-hop delay, and consequently the cumulative end-to-end delay. This paper reviews current asynchronous WSN MAC protocols. Its main contribution is to study these protocols from the delay efficiency perspective, and to investigate on their latency. The asynchronous protocols are divided into six categories: static wakeup preamble, adaptive wake-up preamble, collaborative schedule setting, collisions resolution, receiver-initiated, and anticipation based. Several state-of-the-art protocols are described following the proposed taxonomy, with comprehensive discussions and comparisons with respect to their latency.
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    Slotted Contention-Based Energy-Efficient MAC Protocols in Delay-Sensitive
    (CERIST, 2012) Doudou, Messaoud; Badache, Nadjib; Djenouri, Djamel
    This 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. In order to transmit data from one node to another, both nodes must be in active mode. The synchronous feature makes these protocols more appropriate for delay-sensitive applications compared to 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, contention-based feature makes the protocols --considered in this paper-- conceptually distributed and more dynamic compared to TDMA-based protocols. Duty cycling allows obtaining significant energy saving vs. full duty cycle (sleepless) random access MAC protocols. However, it may result in significant latency. Forwarding a packet over multiple hops often requires multiple operational cycles (sleep latency), where nodes have to wait for the next cycle to forward data at each hop. Timeliness issues of slotted contention-based WSN MAC protocols is deal t with in this paper, where a comprehensive review and taxonomy of state-of-the-art synchronous MAC protocols is provided. The main contribution is to study and classify the protocols from the delay-efficiency perspective.
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    Duo-MAC: Energy and Time Constrained Data Delivery MAC Protocol in Wireless Sensor Networks
    (CERIST, 2013) Doudou, Messaoud; Badache, Nadjib; Djenouri, Djamel; AIaei, Mohammad; Barcelo-Ordinas, Jose M.
    We present Duo-MAC, an asynchronous cascading wake-up scheduled MAC protocol for heterogeneous traffic for- warding in low-power wireless networks. Duo-MAC deals with energy-delay minimization problem and copes with transmission latency encountered by Today’s duty-cycled protocols when forwarding heterogeneous traffic types. It switches, according to the energy and delay requirements, between Low Duty cycle (LDC) and High Duty Cycle (HDC) operating modes, and it quietly adjusts the wake-up schedule of a node according to (i) its parent’s wake-up time and (ii) its estimated load, using an effective real-time signal processing linear traffic estimator. As a second contribution, Duo-MAC, proposes a service differentiation through an improved contention window adaptation algorithm to meet delay requirements of heterogeneous traffic classes. Duo- MAC’s efficiency stems from balancing between the two traffic award operation modes. Implementation and experimentation of Duo-MAC on a MicaZ mote platform reveals that the protocol outperforms other state-of-the-art MAC protocols from the energy-delay minimization perspective.