Networked control over fading channels

Classical control theory assumes that the communication links connecting plants, sensors and controllers are perfect, which however is not true in practical applications. The imperfection of communication channels would introduce uncertainties into feedback control systems, which might impact the stability and performance of the corresponding control system.  This talk focuses on the fading phenomenon in wireless communications and studies how channel fading affects the stability of feedback control systems. In the first part of this talk, we consider the mean square stabilizability problem of linear systems controlled over power constrained fading channels, which suffers from both SNR constraints and the time-varying i.i.d. channel fading. We try to characterize channel requirements for the existence of coding and controlling policies that can mean square stabilize the linear system. We show that there is a fundamental limitation on the mean square stabilizability for networked control over fading channels. In the second part of this talk, we study the consensusability problem of linear multi-agent systems over fading networks. The agents in the multi-agent systems communicate with their neighborhoods through fading channels. We aim to characterize requirements on the agent dynamics, channel capacities and the network topology for the existence of a distributed consensus controller. The results imply that the consensusability is closely related to the statistics of fading networks, the eigenratio of the graph, and the instability degree of the dynamical system.