UEP non-binary LDPC codes: A promising framework based on group codes

In this paper, we address the problem of providing unequal error protection (UEP) with LDPC codes built on finite sets of order strictly greater than 2 (nonbinary codes). The main interest of providing UEP with nonbinary LDPC codes is that future standards are likely to prefer nonbinary coding schemes because of their better robustness to the codeword length and the modulation size. However, the problem of giving UEP properties with nonbinary LDPC codes is much more difficult than with binary LDPC codes. We present a first attempt to solve this difficult problem, based on LDPC codes built on finite groups. The framework and the basis about group LDPC codes are first presented in details, and the framework is used to give examples of UEP nonbinary LDPC codes that actually achieve different UEP properties at the bit level while the symbol error properties are kept equally protected.