Research Reports
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Item Energy-Delay Constrained Minimal Relay Placement in Low Duty-Cycled Sensor Networks Under Anycast Forwarding(CERIST, 2016-06) Doudou, Messaoud; M. Barcelo-Ordinas, Jose; Garcia-Vidal, JorgeA constrained relay placement problem satisfying application requirements in terms of network lifetime and end-to-end (e2e) delay in Wireless Sensor Networks (WSN) is investigated in this paper. The network and the traffic are adequately modeled considering uniform node deployment and low data rate periodic traffic generation. An optimization problem is defined to obtain the minimum number of relays to be deployed, at each level of the network, in order to fulfil network duty-cycle and e2e delay constraints under anycast forwarding based on the wake-up period parameter of the duty-cycle MAC protocol. Since the optimization problem is non-convex, an alternative and efficient algorithm for relay node placement called EDC-RP (Energy-Delay Constrained Relay Placement) is introduced. The comparison of the proposed node deployment strategy with state-of-the-art relay placement methods demonstrates the gain of the heuristic in terms of deployment cost (number of relays) over other solutions while fulfilling the application constraints.Item Efficient QoS-aware Heterogeneous Architecture for Energy-Delay Constrained Connected Objects(CERIST, 2016) 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 An Oscillation-Based Algorithm for Reliable Vehicle Detection with Magnetic Sensors(CERIST, 2016-02-25) Djenouri, Djamel; Doudou, Messaoud; Kafi, Mohamed AmineVehicle monitoring using a wireless sensor network is considered in this paper, where a new algorithm is proposed for vehicle detection with magnetic sensors. The proposed algorithm is based on processing the magnetic signal and thoroughly analyzing the number/direction of its oscillations. The main feature of the proposed algorithm over the state-of-the-art ones is its capability to detect vehicles with different shapes of signatures, while most state-of-the-art algorithms assume regular shapes of signatures. This makes the algorithm effective with all types of magnetic sensors. The proposed algorithm has been implemented on Micaz sensor motes and tested in real word scenarios. Results show reliability beyond 93% in all samples, and more than 95% in most of them.Item DZ50: Energy-Efficient Wireless Sensor Mote Platform for Low Data Rate Applications(CERIST, 2014-07-07) Ouadjaout, Abdelraouf; Lasla, Noureddine; Bagaa, Miloud; Doudou, Messaoud; Zizoua, Cherif; Kafi, Mohamed Amine; Derhab, Abdelouahid; Djenouri, Djamel; Badache, NadjibA low cost and energy efficient wireless sensor mote platform for low data rate monitoring applications is presented. The new platform, named DZ50, is based on the ATmega328P micro-controller and the RFM12b transceiver, which consume very low energy in low-power mode. Considerable energy saving can be achieved by reducing the power consumption during inactive (sleep) mode, notably in low data rate applications featured by long inactive periods. Without loss of generality, spot monitoring in a Smart Parking System (SPS) and soil moisture in a Precision Irrigation System (PIS) are selected as typical representative of low data rate applications. The performance of the new platform is investigated for typical scenarios of the selected applications and compared with that of MicaZ and TelosB. Energy measurement has been carried out for different network operation states and settings, where the results reveal that the proposed platform allows to multiply the battery lifetime up to 7 times compared to MicaZ and TelosB motes in 10s sampling period scenarios.Item Game Theoretical Approach for Energy-Delay Balancing in Distributed Duty-Cycled MAC Protocols of Wireless Networks(CERIST, 2014-04-24) Doudou, Messaoud; M. Barcelo-Ordinas, Jose; Djenouri, Djamel; Garcia-Vidal, Jorge; Badache, NadjibOptimizing energy consumption and end-to-end (e2e) packet delay in energy constrained distributed wireless networks is a conflicting multi-objective optimization problem. This paper investigates this trade-off from a game-theoretic perspective, where the two optimization objectives are considered as virtual game players that attempt to optimize their utility values. The cost model of each player is mapped through a generalized optimization framework onto protocol specific MAC parameters. From the optimization framework, a cooperative game is defined in which the Nash Bargaining solution assures the balance between energy consumption and e2e packet delay. For illustration, this formulation is applied to three state-of-the-art wireless sensor network MAC protocols; X-MAC, DMAC, and LMAC as representatives of preamble sampling, slotted contention-based, and frame-based MAC categories, respectively. The paper shows the effectiveness of such framework in optimizing protocol parameters that achieve a fair energy-delay performance trade-off under the application requirements in terms of initial energy budget and maximum e2e packet delay. The proposed framework is scalable with the increase in the number of nodes, as the players represent the optimization metrics instead of nodes.Item 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, NadjibThe 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.Item 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 ZohraThis 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.Item Survey on Latency Issues of Asynchronous MAC Protocols in Delay-Sensitive Wireless Sensor Networks(CERIST, 2012) Doudou, Messaoud; Badache, Nadjib; Djenouri, DjamelEnergy-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.Item Slotted Contention-Based Energy-Efficient MAC Protocols in Delay-Sensitive(CERIST, 2012) Doudou, Messaoud; Badache, Nadjib; Djenouri, DjamelThis 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.Item Synchronous Contention-Based MAC Protocols for Delay-Sensitive Wireless Sensor Networks: a Review and Taxonomy(CERIST, 2012) Doudou, MessaoudIn slotted duty-cycled medium access control (MAC) protocols, sensor nodes periodically and synchronously alternate their operations between active and sleep modes. The sleep mode allows a sensor node to completely turn off its radio and save energy. In order to transmit data from one node to another, both nodes must be in active mode. The synchronous feature makes the protocols more appropriate for delay-sensitive applications compared to asynchronous protocols. The latter involve additional delay for the sender to meet the receiver’s active period, which is eliminated with synchronous approach where nodes sleep and wake up all together. On the other hand, contention-based feature makes the protocol conceptually distributed and more dynamic compared to TDMA-based. Duty cycling allows obtaining significant energy saving compared to 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. This manuscript deals with timeliness issues of slotted contention-based WSN MAC protocols. It provides a comprehensive review and taxonomy of state-of-the-art synchronous MAC protocols. The main contribution is to study and classify these protocols from the delay efficiency perspective. The protocols are divided into two main categories: static schedule and adaptive schedule. Adaptive schedule are split up into four subclasses: adaptive grouped schedule, adaptive repeated schedule, staggered schedule, and reservation schedule. Several state-of-the-art protocols are described following the proposed classification, with comprehensive discussions and comparisons with respect to their latency.