Observer design for descriptor networked control systems with unknown and partially known inputs

Sufficient conditions are given for the existence of unknown and partially known input normal and descriptor observers for a class of descriptor discrete time networked control systems.It is shown that a causal and regular descriptor system subjected to input and output periodic communication constraints,can be down sampled into a causal and regular p-lifted time invariant system.According to the lifted formulation,interesting results on minimum and maximum feasible values for communication sequence periods are drawn for the existence of an unknown or partially known input observer.The case of partially known input observer,cover unknown input case as an extreme case.An example is given for clarification.