Messaoud Doudou

Review: Synchronous contention-based MAC protocols for delay-sensitive wireless sensor networks: A review and taxonomy

Duty-cycling allows obtaining significant energy saving compared to full duty cycle (sleepless) random access MAC protocols. However, it may result in significant latency. In 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 receivers active period, which is eliminated with synchronous approach where nodes sleep and wake up all together. Despite the possible increase of contention by grouping active periods, the delay due to packets retransmissions after collisions is less significant compared to the waiting time of asynchronous protocols. Furthermore, contention-based feature makes the protocol conceptually distributed and more dynamic compared to TDMA-based. 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 performance objective considered in the proposed taxonomy is the latency, in the context of energy-limited WSN, where energy is considered as a constraint for the MAC protocol that yields the need of duty-cycling the radio. 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.

A Study of Wireless Sensor Networks for Urban Traffic Monitoring: Applications and Architectures

Abstract With 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.

DZ50: Energy-efficient Wireless Sensor Mote Platform for Low Data Rate Applications☆

Abstract A low cost and energy e_cient 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 measurements have been carried out for di_erent 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.

Game Theory Framework for MAC Parameter Optimization in Energy-Delay Constrained Sensor Networks

Optimizing energy consumption and end-to-end (e2e) packet delay in energy-constrained, delay-sensitive wireless sensor networks is a conflicting multiobjective 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. Secondy, the Kalai-Smorodinsky bargaining solution (KSBS) is used to find an 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 that 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 article shows the effectiveness and scalability of such a framework in optimizing protocol parameters that achieve a fair energy-delay performance trade-off under the application requirements.

Duo-MAC: Energy and time constrained data delivery MAC protocol in wireless sensor networks

We present Duo-MAC, an asynchronous cascading wake-up scheduled MAC protocol for heterogeneous traffic forwarding in low-power wireless networks. Duo-MAC deals with energy-delay minimization problem and copes with transmission latency encountered by Todays 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 parents 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-MACs 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.

Efficient QoS-aware heterogeneous architecture for energy-delay constrained connected objects

Connected 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.

FH-MAC: A Multi-Channel Hybrid MAC Protocol for Wireless Mesh Networks

In this article, the authors propose a new hybrid MAC protocol named H-MAC for wireless mesh networks. This protocol combines CSMA and TDMA schemes according to the contention level. In addition, it exploits channel diversity and provides a medium access control method that ensures the QoS requirements. Using ns-2 simulator, we have implemented and compared H-MAC with other MAC protocol used in Wireless Network. The results showed that H-MAC performs better compared to Z-MAC.

Performance Specifications of Market Physiological Sensors for Efficient Driver Drowsiness Detection System

Significant advances in bio-sensors technologies hold promise to monitor human physiological signals in real time. In the context of driving safety, such devices are knowing notable research investigations to objectively detect early stages of driver drowsiness that impair driving performance under various conditions. Seeking for low-cost, compact yet reliable sensing technology that can provide a solution to drowsy state problem is challenging. The contribution of this paper is to study fundamental performance specifications required for the design of efficient physiological signals based driver drowsiness detection systems. Existing measurement products are then accessed and ranked following the discussed performance specifications. The finding of this work is to provide a tool to facilitate making the appropriate hardware choice to implement efficient yet low-cost drowsiness detection system using existing market physiological sensors products.

Energy-delay constrained minimal relay placement in low duty-cycled sensor networks under anycast forwarding

A 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.

An oscillation-based algorithm for reliable vehicle detection with magnetic sensors

Vehicle 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 world scenarios. Results show reliability beyond 93% in all samples, and more than 95% in most of them.