| The Controller Area Network (CAN) is employed widely in modern automobiles, medical instrumentation, tactical vehicles, building automation, metropolitan transportation, and manufacturing control systems. DeviceNet is one example of a commercial SCADA network that is based on the CAN specification. Most, if not all, critical infrastructure control systems make use of a CAN or CAN-like network at some point in their layout for connecting remote sensors to indicators and controllers to actuators, or to link multiple controllers to a common user interface.; The IEEE 802.15.4 wireless standard was finalized in late 2003. Commercially known as "ZigBee," this system is designed to operate at low data rates with secure, low cost network configurations. Such a network is commonly referred to as a low-rate wireless personal area network (LR-WPAN). LR-WPANs are often used for home networking, medical instrumentation, and other applications which require very low power remote sensors in order to optimize battery life and minimize sensor maintenance. Two key elements of the IEEE 802.15.4 LR-WPAN standard are low power operation and inherent security implementation.; This dissertation proposes an architecture to extend CAN to the wireless domain of the IEEE 802.15.4 LR-WPAN, thereby providing a low cost, low power, efficient, and secure wireless network interface compatible with many existing SCADA infrastructure networks, in addition to the countless other installations incorporating a CAN backbone. An architectural model for such an extension mechanism is proposed which includes additions to the CAN protocol stack. New protocols are recommended for the tunneling of messages and for enhancing reliability.; Results obtained indicate successful protocol compliance and net message delay times well within the advertised specification of ten milliseconds per hop for non-secure messages. Additional latency for security processing was found to increase message delay by approximately 7.5 milliseconds. The predicted launch times for normal and GTS messages in beacon-enabled networks were also verified. |
