Controller and Scheduler Codesign for Feedback Control Over IEEE 802.15.4 Networks

In this paper, we examine the impact of the scheduling policy on the performance for feedback control over networks based on a hybrid communication protocol, which incorporates both contention-free and contention-based medium access. We investigate the possibilities and limitations of feedback control in the IEEE 802.15.4 specification and state the problem of scheduling when the controller both utilizes the contention-based and guaranteed parts of the protocol. We propose and compare a number of scheduler-controller codesign algorithms that take both the contention-based and guaranteed parts of the protocol into account using an approximation to an infinite horizon linear quadratic cost function. The simulation studies show that a careful codesign of the scheduler-controller results in significant performance gains, when using both online and offline scheduling policies.