FaultTolerant Online Scheduling Algorithms for CubeSats CubeSats are small satellites operating in harsh space environment. In order to ensure correct functionality on board despite faults, fault tolerant techniques taking into account spatial, time and energy constraints should be considered. This paper presents a softwarelevel solution taking advantage of several processors available on board. Two online scheduling algorithms are introduced and evaluated. The results show their performances and the tradeoff between the rejection rate and energy consumption. Last but not least, it is stated that ordering policies achieving low rejection rate when using the algorithm scheduling all tasks as aperiodic are the Earliest Deadline and Earliest Arrival Time. As for the algorithm treating arriving tasks as aperiodic or periodic tasks, the Minimum Slack ordering policy provides reasonable results.

Scheduling Periodic and Aperiodic Tasks with Time, Energy Harvesting and Precedence Constraints on Multicore Systems Abstract   This paper deals with the realtime scheduling problem of multicore systems powered by renewable energy harvested from environment. They handle two types of software tasks which are mapped to cores statically and not allowed to migrate. A task can be periodic which may depend on other tasksxe2x80x99 results, or aperiodic which is added to the system to cope with external interruptions. The uncertainty of energy availability in energy harvesting systems makes realtime scheduling more challenging because energy constraints can be violated to ensure realtime performance. A novel scheduling strategy is proposed to effectively compute deadlines allowing for tasks and messages to meet related constraints. This method consists of two phases, i) the first one defines different time slots each of which is characterized by energy and frequency parameters to cope with the energy availability issue, and ii) the second one calculates the deadlines ensuring realtime system feasibility by considering the invocation of aperiodic task execution and task precedence constraints. The originality of the current work compared with related studies is that it deals with multicore, periodic and aperiodic tasks, dependency, energy harvesting, and realtime aspects simultaneously.