Information efficiency of communications for networked control in cyber physical systems: When carnot meets shannon

Abstract

Communication is of key importance for networked control in cyber physical systems (CPSs). Motivated by the second law of thermodynamics, Shannon entropy is used to characterize the disorderliness of the physical dynamics in CPSs; thus communication provides negative entropy, namely information, to compensate the generation of entropy. Under mild conditions, it is shown that the entropy reduction in the physical dynamics is upper bounded by the information provided by the communication system. Hence, similarly to the Carnot heat engine efficiency, the information efficiency in CPS is defined to characterize the information utilization. Both upper and lower bounds are obtained for the information efficiency under various scenarios. The discussion on generic CPSs is then applied in concrete examples of Szilard engine and scalar linear dynamics. Numerical results for the maximal information efficiency, obtained from numerical optimizations, are provided.