TITLE:      Error-correcting two-dimensional modulation codes
AUTHORS:    W. H. Erxleben and M. W. Marcellin
JOURNAL:    IEEE Transactions on Information Theory
ABSTRACT:
Modulation coding, to limit the number of consecutive zeroes in a data
stream, is essential in digital magnetic recording/playback
systems.  Additionally, such systems require error correction coding to
ensure that the decoded output matches the recorder input, even if noise
is present.  Typically these two coding steps have been performed
independently, although various methods of combining them into one step
have recently appeared.  Another recent development is two-dimensional
modulation codes, which meet runlength constraints using several parallel
recording tracks, significantly increasing channel capacity.  This
correspondence combines these two ideas.  Previous techniques (both block and
trellis structures) for combining error correction and modulation coding are
surveyed, with discussion of their applicability in the two-dimensional
case.  One approach, based on trellis-coded
modulation, is explored in detail, and a class of codes are developed which
exploit the increased capacity to achieve good error-correcting ability
at the same rate as common non-error-correcting one-dimensional codes.