On Future-Dependent Block Coding for Input-Restricted Channels

Consider a restricted channel whose constraints may be characterized by a finite state machine model. Conventional coding techniques for such channels result in codes where the choice of a word to be transmitted is only a function of the current state and the information to be represented by this word. This paper develops techniques for constructing codes where the code word choice may also depend on future information to be transmitted. It is shown that such future-dependent codes exist for channels and coding rates where no conventional code may be constructed.