Coding for Constrained Channels: A Comparison of Two Approaches

We discuss the relation between some early techniques for constrained channel coding and more recent ones adapted from the mathematical area of symbolic dynamics. A primary difference between the two is that the latter focus on issues of code existence, whereas the former were primarily concerned with code construction and optimality. 1. Introduction One of the more notable developments in information theory within the last few years has been the discovery [ I ] of the relationship between the recent work in the mathematical area of symbolic dynamics and what is often termed channel coding. Aside from the work [ 11 by Adler, Coppersmith, and Hassner (referred to here as ACH), this has led to such significant results as those of Marcus [ 2 ] , and in general this development has substantially improved the mathematical underpinnings