Path Pruning for Unequal Error Protection Turbo Codes

For some applications in communications, it is desirable to provide unequal error protection for different types of information data. In image coding, e.g., types of bits exist which have to be protected with different protection levels when transmitting these data over noisy channels. In this paper, we concentrate on turbo codes C. Berrou et al., 1993) with unequal error protection capabilities which are achieved by modifying the code rate R = k/n. After pointing out that puncturing and path pruning are modifications of the rate in the denominator and numerator, respectively, the latter is studied in more detail. Design rules are given and EXIT charts for performance analysis of turbo codes with path-pruned convolutional component codes are presented