  Networked control systems (NCS) have attracted considerable attention in
recent years. While the stabilizability and optimal control of NCS for a given
communication system has already been studied extensively, the design of the
communication system for NCS has recently seen an increase in more thorough
investigation. In this paper, we address an optimal scheduling problem for a
set of NCS sharing a dedicated communication channel, providing performance
bounds and asymptotic stability. We derive a suboptimal scheduling policy with
dynamic state-based priorities calculated at the sensors, which are then used
for stateless priority queuing in the network, making it both scalable and
efficient to implement on routers or multi-layer switches. These properties are
beneficial towards leveraging existing IP networks for control, which will be a
crucial factor for the proliferation of wide-area NCS applications. By allowing
for an arbitrary number of concurrent transmissions, we are able to investigate
the relationship between available bandwidth, transmission rate, and delay. To
demonstrate the feasibility of our approach, we provide a proof-of-concept
implementation of the priority scheduler using real networking hardware.
