LQG and Medium Access Control ?

The communication channel is a shared resource in networked control systems, and channel access at every instant cannot be guaranteed. In this paper, we propose a novel architecture for control over wireless networks with integrated medium access control (MAC). We evaluate the impact of constrained channel access on the cost of controlling a single plant over a network and establish that the separation principle holds under certain conditions on the MAC. We arrive at a classification of random access methods for networked control systems and identify a structure for each method. Then, by evaluating the increase in cost compared to a conventional setup, we identify an adaptive random access method which uses a threshold-based decision criteria on the current data to determine channel access. Finally, we give stability criteria for control applications using these medium access methods.