This paper considers the stability problem of networked control systems (NCS) with node devices acting over a limited communication channel. The feedback loops of the NCS are realized via observer-based dynamics. An iterative approach is proposed to model networked control systems with periodic transmission policy and arbitrary transmission policy as linear discrete time systems and switched linear systems, respectively. Sufficient conditions are presented on stability of the NCS. The merit of the iterative approach is that the controllers can make full use of the previous information to stabilize NCS when the current state measurements are available from the network. A simulation example is worked out to illustrate the effectiveness of the proposed approach.