Constrained Codes as Networks of Relations

We address the well-known problem of determining the capacity of constrained coding systems. While the onedimensional case is well understood to the extent that there are techniques for rigorously deriving the exact capacity, in contrast, computing the exact capacity of a two-dimensional constrained coding system is still an elusive research challenge. The only known exception in the two-dimensional case is an exact (however, not rigorous) solution to the (1, )-RLL system on the hexagonal lattice. Furthermore, only exponential-time algorithms are known for the related problem of counting the exact number of constrained two-dimensional information arrays. We present the first known rigorous technique that yields an exact capacity of a two-dimensional constrained coding system. In addition, we devise an efficient (polynomial time) algorithm for counting the exact number of constrained arrays of any given size. Our approach is a composition of a number of ideas and techniques: describing ...

• Type: Journal
• Year: 2008
• Where: TIT
• Authors: Moshe Schwartz, Jehoshua Bruck
• Keywords: Constrained Coding, Exact Capacity, TIT 2008, Two-dimensional Constrained Coding