A Reliable Job Allocation Scheduler for Time-Triggered Wireless Networks

The job allocation problem is a challenging in wireless systems, because the spatial and temporal distribution of dependent jobs to hosts must satisfy the precedence constraints, prevent communication interference and minimize energy consumption. In this paper, a new scheduler called Reliable Job Allocation scheduler (RJA) is proposed to improve the reliability of realtime wireless systems. The proposed scheduler uses an approach called Frame Replication and Elimination for Reliability (FRER) to replicate the communication flows through redundant routes. RJA considers the periodicity of Time-Triggered (TT) flows and the impact of the induced interference, by applying a physical interference model which is used to ensure that all flows are transmitted successfully in the assigned time-slots. The scheduling efficiency and the system reliability are improved through allocating jobs to hosts with high performance in terms of flow arrival time, energy consumption and failure rates. A reliability model is also introduced to determine the reliability of the system. The reliability model computes the reliability of each job depending on the reliability of all its incoming flows. The reliability of the leaf job, which has no forwarding flows, presents the global reliability of the overall system. RJA is compared with state-of-the-art TT schedulers that use either the shortest or load-aware routes to send flows without addressing reliability. The experimental results show that the reliability of the system computed by RJA is improved compared to the other schedulers while also ensuring scalability in the network design (i.e. increase of the number of jobs and hosts) and timeliness. We also study the impact of the injected link failures on the flow delivery ratio.