Reducing CAN latencies by use of weak synchronization between stations

Scheduling frames with offsets has been shown in the literature to be very beneficial for reducing response times in real-time networks because it allows the workload to be better spread over time and thus to reduce peaks of load. Maintaining a global synchronization amongst the stations induces substantial overhead and complexity in networks not providing a global time service such as CAN. Indeed, on CAN, a global clock is rarely implemented in practice and each station possesses its own local clock. Without a global clock, the de-synchronization between the streams of frames created by offsets remains local to each station and thus less efficient. In a previous paper [1], we developed a method to compute latency upper bounds for set of messages with offsets when the inter-node synchronization is not perfect. On a simplified test case, we obtained a reduction of 65% of the delay using a clock accuracy of only 1ms. In this article, we extend the method to consider a realistic case study (mixing periodic and asynchronous flows, considering errors and tacking into account the synchronization protocol)