New low-complexity turbo-like codes

We discuss the design of new low-complexity turbo-like codes based on a multiple parallel concatenation of 4-state and 2-state constituent codes. The new code designs take advantage of the big-numerator/little-denominator principle along with specially designed interleavers to outperform previously designed turbo codes over the entire range of signal-to-noise ratios. Puncturing at the encoder is used to produce low-complexity codes with excellent performance at code rates of 1/2 and 1/3. The multiple parallel concatenation and puncturing results in turbo-like encoders which are either partially systematic or completely nonsystematic. Comparisons with the proposed 8-state turbo coding standard and with other low-complexity alternative code designs are included.