Structured low-density parity-check codes

Iterative coding techniques that improve the reliability of input-constrained, intersymbol interference (ISI) channels have recently attracted considerable attention for data storage applications. Inspired by the success of turbo codes [6], several authors have considered iterative decoding architectures for coding schemes comprised of a concatenation of an outer block, convolutional or turbo encoder with a rate one code representing the channel. Such an architecture is equivalent to a serial concatenation of codes [4], with the inner code being the ISI channel. Application of this concatenated scheme in magnetic and optical recording systems is considered in [23, 24].