Research Reports

Permanent URI for this collectionhttp://dl.cerist.dz/handle/CERIST/34

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Author: search.filters.author.Djenouri, DjamelSubject: search.filters.subject.Wireless Sensor Networks

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Now showing 1 - 7 of 7
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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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    Distributed Receiver/Receiver Synchronization in Wireless Sensor Networks: New Solution and Joint Offset/Skew Estimators for Gaussian Delays
    (CERIST, 2011-06) Djenouri, Djamel
    This paper proposes a synchronization protocol for wireless sensor networks (WSN). The receiver/receiver approach inspired from Reference Broadcast Synchronization (RBS) protocol is chosen for its lower time-critical path compared to the sender/receiver approach. Contrary to RBS upon which rely all current receiver/receiver solutions, the proposed one is totally distributed and does not depend on any fixed reference. The reference’s function is balanced among all sensors, which eliminates the single point of failure shortcomings. RBS needs additional steps for exchanging reception timestamps. On the other hand, the proposed protocol allow these timestamps to be piggybacked to the regular beacons, reducing thus the overhead and energy consumption. The protocol deals with local synchronization and allows neighboring nodes to relatively synchronize with each other by estimating relative skews/offsets. Maximum Likelihood estimators (MLEs) are derived for channels with Gaussian (normal) distributed delays, and for both offset-only and joint offset/skew models. The Cramer- Rao Lower Bounds (CRLBs) are derived for each model and numerically compared with the MLE. Results show quick convergence of the proposed estimators’ precision to CRLB. Like the CRLB, the mean square errors (MSE) of the estimators quadratically decrease toward zero as the number of messages increases. To our knowledge, this is the first distributed receiver/receiver solution that eliminates the need of a fixed reference while taking advantage of the receiver/receiver synchronization’s precision.
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    Fault-Tolerant Implementation of a Distributed MLE-based Time Synchronization Protocol for Wireless Sensor Networks
    (CERIST, 2012) Djenouri, Djamel; Doudou, Messaoud; Merabtine, Nassima; Mekahlia, Fatma Zohra
    This paper describes the implementation and evaluation of R4Syn protocol on MICAz platform and TinyOS operating system. The contribution is two folds. First, the implementation uses thorough maximum-likelihood estimators (MLE) in the joint offset/skew model, while all similar MLE-based estimators are merely evaluated with theoretical and numerical analysis thus far, and empirical solutions use simple computation estimators, such as offset-only models, or linear regression for skew estimation. Difficulties that has been encountered and overcome are reported in this paper. The second contribution is to consider fault-tolerance, an aspect that has been completely abstracted in previous works. The implementation assures correct behavior despite nodes failure or packet loss, as demonstrated by the experiments. Experimental results also demonstrate microsecond-level precision and long-term validity of the estimators in the joint skew/offset model.
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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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    On the Relevance of Using Interference and Service Differentiation Routing in the Internet-of-Things
    (CERIST, 2013) Djenouri, Djamel; Bagula, Antoine; Karbab, Elmouatezbillah
    Next generation sensor networks are predicted to be deployed in the Internet-of-the-Things (IoT) with a high level of heterogeneity, using a model where the sensor motes will be equipped with different sensing and communication devices and tasked to deliver different services leading to different energy consumption patterns. The application of traditional wireless sensor routing algorithms designed for sensor motes expanding the same energy to such heterogeneous networks may lead to energy unbalance and subsequent short-lived sensor network resulting from routing the sensor readings over the most overworked sensor nodes while leaving the least used nodes idle. Building upon sensor devices service identification, this paper assess the relevance of using sensor node service differentiation to achieve efficient traffic engineering in IoT settings and its relative efficiency compared to traditional sensor routing. Performance evaluation with simulation reveals clear improvement of the proposed protocol vs. state of the art solutions in terms of load balancing, notably for critical nodes that cover more services. Results show that the proposed protocol considerably reduce the number of packets routed by critical nodes, where the difference with the compared protocol becomes more and more important as the number of nodes rises. Results also show clear reduction in the average energy consumption.
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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.