Document Type

Technical Report


Computer Science and Engineering

Publication Date






Technical Report Number



Recent years have witnessed the adoption of wireless sensor-actuator networks as a communication infrastructure for process control applications. An important enabling technology for industrial process control is WirelessHART, an open wireless sensor-actuator network standard specifically developed for process industries. A key challenge faced byWirelessHART networks is to meet the stringent real-time communication requirements imposed by feedback control systems in process industries. Fixed priority scheduling, a popular scheduling policy in real-time networks, has recently been shown to be an effective real-time transmission scheduling policy in WirelessHART networks. Priority assignment has a major impact on the schedulability of real-time flows in these networks. This paper investigates the open problem of priority assignment for periodic real-time flows for feedback control loops closed through a WirelessHART network. We first propose an optimal priority assignment algorithm based on branch and bound for any given worst case delay analysis. We then propose an efficient heuristic search algorithm for priority assignment. We also identify special cases where the heuristic search is optimal. Simulations based on random networks and the real topology of a physical sensor network testbed showed that the heuristic search algorithm achieved near optimal performance in terms of schedulability, while significantly outperforming traditional real-time priority assignment policies.


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