Modified target and concatenated coding for d=1 constrained magnetic recording channels

Constrained Parity-Check Code and Post-Processor for Advanced Blue Laser Disc Systems

“…Most of the prior art schemes design codes in the NRZI format. [9][10][11][12] Using the proposed code design technique, constrained PC codes can be designed either in NRZI format or in NRZ format. For PC codes and post-processing based detection approaches, we find it preferable to impose the PC constraint on the NRZ sequence at the output of the precoder, rather than on the NRZI sequence at the input of the precoder.…”

“…Since the modulation constraints should also be simultaneously satisfied, an additional code rate loss will be incurred. Although many attempts have been taken by researchers in recent years to efficiently combine the constrained codes with the PC codes, [9][10][11][12] the systematic design of constrained PC codes with minimum code rate loss remains an open problem. It is especially difficult to design constrained PC codes that satisfy multiple-bit PC constraints for the optical recording systems.…”

A general construction of constrained parity-check codes for optical recording

“…Gopalaswamy and Bergmans [16] proposed concatenated coding to construct modulation codes with error detection capability. In this scheme, the PC information is first calculated for each constrained data block.…”

“…A combi-code scheme proposed by Coene et al [11] achieves high efficiency similar to [16], and avoids the paritybit related error propagation. In this scheme, the constrained PC code consists of two sliding block codes, which are designed to detect single-bit transition shift errors (i.e.…”

“…The constrained encoded bits before and after the precoder are referred to as a non-return-to-zero-inverse (NRZI) sequence, and a non-return-to-zero (NRZ) sequence, respectively. Most of the prior art schemes design codes in the NRZI format [15], [16], [11], [17].…”