Real-time scheduling for energy harvesting sensor nodes

Energy harvesting has recently emerged as a feasible option to increase the operating time of sensor networks. If each node of the network, however, is powered by a fluctuating energy source, common power management solutions have to be reconceived. This holds in particular if real-time responsiveness of a given application has to be guaranteed. Task scheduling at the single nodes should account for the properties of the energy source, capacity of the energy storage as well as deadlines of the single tasks. We show that conventional scheduling algorithms (like e.g. EDF) are not suitable for this scenario. Based on this motivation, we have constructed optimal scheduling algorithms that jointly handle constraints from both energy and time domain. Further we present an admittance test that decides for arbitrary task sets, whether they can be scheduled without deadline violations. To this end, we introduce the concept of energy variability characterization curves (EVCC) which nicely captures the dynamics of various energy sources. Simulation results show that our algorithms allow significant reductions of the battery size compared to Earliest Deadline First schedulin

Task Scheduling in Energy Harvesting Real-time Embedded Systems

International audienceHarvesting energy from the environment is very desirable for many emerging applications that use embedded devices. Energy harvesting also known as energy scavenging enables us to guarantee quasi-perpetual system operation for wireless sensors, medical implants, etc. without requiring human intervention which is normally necessary for recharging batteries in classical battery-operated systems. Nevertheless, energy harvesting calls for solving numerous technological problems in relation with chemistry when batteries are used for temporary energy storage for example, power management of the embedded computing system that consumes the energy, etc. And this latter problem becomes more complex when the embedded system has real-time constraints i.e. deadlines attached to computations. This paper surveys the main issues involved in designing energy harvesting embedded systems that present strict timing requirements

ASTORE : Autonomie des Systèmes embarqués par la Technologie de l'Ordonnancement temps réel et la Récupération de l'Énergie renouvelable

National audienceDans la conception d'un système temps réel embarqué il existe plusieurs attributs dont le développeur doit tenir compte. Premièrement, le produit final doit être correct d'un point de vue fonctionnel. Deuxièmement, sa performance exprimée en termes de temps de réponse doit être satisfaisante et conforme aux spécifications. Et troisièmement, lorsqu'il utilise une batterie comme source d'alimentation, son fonctionnement doit s'adapter à la quantité d'énergie disponible. Comme l'altération d'un de ces attributs va altérer les deux autres, la conception d'un système embarqué passera par la considération conjointe des aspects temporels et énergétiques. Notre objectif est de prouver sur un démonstrateur l'efficacité d'une stratégie qui combine ordonnancement temps réel et gestion énergétique visant à assurer un fonctionnement perpétuel qualifié d'énergétiquement neutre

Energy harvesting earliest deadline first scheduling algorithm for increasing lifetime of real time systems

In this paper, a new approach for energy minimization in energy harvesting real time systems has been investigated. Lifetime of a real time systems is depend upon its battery life.  Energy is a parameter by which the lifetime of system can be enhanced.  To work continuously and successively, energy harvesting is used as a regular source of energy. EDF (Earliest Deadline First) is a traditional real time tasks scheduling algorithm and DVS (Dynamic Voltage Scaling) is used for reducing energy consumption. In this paper, we propose an Energy Harvesting Earliest Deadline First (EH-EDF) scheduling algorithm for increasing lifetime of real time systems using DVS for reducing energy consumption and EDF for tasks scheduling with energy harvesting as regular energy supply. Our experimental results show that the proposed approach perform better to reduce energy consumption and increases the system lifetime as compared with existing approaches.

Cooperative energy harvesting-adaptive MAC protocol for WBANs

In this paper, we introduce a cooperative medium access control (MAC) protocol, named cooperative energy harvesting (CEH)-MAC, that adapts its operation to the energy harvesting (EH) conditions in wireless body area networks (WBANs). In particular, the proposed protocol exploits the EH information in order to set an idle time that allows the relay nodes to charge their batteries and complete the cooperation phase successfully. Extensive simulations have shown that CEH-MAC significantly improves the network performance in terms of throughput, delay and energy efficiency compared to the cooperative operation of the baseline IEEE 802.15.6 standard.Peer ReviewedPostprint (published version

Energy-aware task allocation for energy harvesting sensor networks

10.1186/s13638-015-0490-3Eurasip Journal on Wireless Communications and Networking201611-1