Challenges in Real-time Scheduling for Energy Harvesting Embedded Systems

Abstract

The recent and rapid development of the Internet of Things (IoT’) leads to the need for embedded devices that comprise one or more resource-constrained computing elements and sensors. Energy Harvesting (EH) technology provides the ability for any low-power embedded device to operate thanks to the generation of electricity from the energy available in the device's immediate surroundings such as light or motion. Energy neutrality is the central requirement of autonomous real-time computing systems that should be designed to correctly function for long times with no possible manual intervention to charge or replace batteries. Unfortunately, most of environmental energy sources are fluctuating and not controllable. It means that a stable power supply cannot be relied upon that makes challenging the issue of compliance with hard real-time constraints. Specific power management and scheduling solutions have to be conceived in order to prevent energy starvation and guarantee real-time responsiveness. Task scheduling should take into account not only the timing parameters of the deadline constrained tasks such as worst-case execution times but also energy consumptions, profile of the energy source and capacity of the energy storage unit. The classical greedy scheduler Earliest Deadline First (EDF) or Rate Monotonic (RM) used in battery powered devices should be revisited for this novel operational context. This keynote discusses the state of the art as well as our findings in real-time scheduling and dynamic processor management for autonomous embedded systems. Short biography: Maryline Chetto is currently a full professor in computer engineering with Nantes Université, France and researcher with CNRS. She received the degree of Docteur de 3ème cycle in control engineering and the degree of Habilitee á Diriger des Recherches in Computer Science from the University of Nantes, France, in 1984 and 1993, respectively. From 1984 to 1985, she held the position of Assistant professor of Computer Science at the University of Rennes, while her research was with the Institut de Recherche en Informatique et Systemics Aléatoires (IRISA), Rennes. In 1986, she returned to Nantes and has been from 2002 a full professor with the University of Nantes. She is conducting her research at Laboratoire des Sciences du Numérique de Nantes (LS2N, UMR CNRS no 6004) in the Real Time System group.