Realization of noncausal 2-D systems based on a descriptor model

It is shown that a class of linear discrete noncausal two-dimensional systems can be represented by discrete descriptor systems whose coefficients are functions that admit Laurent series expansions on the unit circle in the complex plane. The basic idea is to obtain a conventional state-space realization with coefficient functions for causal and anticausal subsystems in one direction, and then view them as a descriptor system-a single entity. The resulting model is a 1-D descriptor system with coefficient functions defined on the unit circle in the complex plane. Some properties of this model concerning minimality are also investigated