Analysis of coding schemes for modulation and error control

Several techniques for constructing practical codes for noisy modulation channels represented by (d,k) constraints, such as in magnetic and optical recording, are analyzed. Concatenated schemes based on inner sliding-window codes are compared with concatenated schemes based on inner block codes in terms of efficiency and reliability. The performance of the schemes is investigated in detail for (1,7) constrained channels with different error characteristics. It is shown that for such channels, concatenated schemes based on inner sliding-window codes have higher code rates than concatenated schemes based on inner block codes for typical applications. However, if the channels are very noisy or extremely small decoding error probabilities are required, then the latter schemes tend to have higher code rates than the former ones.