Expected Completion Time Aware Message Scheduling for UM-BUS Interconnected System

Predictable message transmission is the primary requirement in networked safety critical embedded systems design. In these systems, delay jitter has been proven to be a critical factor that must be considered. For periodic messages, minimizing the delay jitter means messages should be transmitted at the expected time in every period. In this paper, we investigate the scheduling problem to reduce the delay jitter for periodic messages in networked safety critical embedded systems. Our approach is empirically assigning an expected completion time as a baseline for the periodic messages and minimizing the total deviation to them. It can be applied either in centralized control buses or in synchronized ones. This paper selects a novel bus protocol and UM-BUS, to evaluate the effectiveness of the proposed algorithm. UM-BUS is a multi-master bus with the capability of multi-lane concurrent transmission. Aiming at different operation mode of UM-BUS, we implemented two sets of experiments by configuring different parameters to change the bus utilization. The results show that the heuristic algorithm works effectively and can achieve a deviation within 0.35%, which is significantly smaller comparing with the existing scheduling algorithms.