Abstract
Controller Area Network (CAN) is a control network protocol that can be found in a wide range of embedded systems. Control networks are inherently real-time local area networks (LANs) whose correct performance is specified in terms of the reliable and timely delivery of messages. These networks are typically required to provide long periods of uninterrupted service in harsh and dynamic environments. Under these conditions, the network is prone to transient-surges in loading that tend to upset temporal behavior. During transient-surges, it is highly desirable to sustain the timely transmission of critical messages. In this effort we describe a protocol that provides Quality of Service (QoS) support for critical real-time message transmissions under nominal conditions and during transient-surges. Our approach uses the CAN protocol in conjunction with a time-value scheduling algorithm. The QoS support for individual message transmissions considers system-state, network loading, and the value of pending messages with respect to time.