Design of Unequal Error Protection LDPC Codes for Higher Order Constellations

We present an optimization method for unequal error protection (UEP)-LDPC codes with higher order constellations. By modifying the density evolution algorithm under the Gaussian approximation, we propose a flexible code design algorithm for a variable number of protection classes and arbitrary modulation schemes with Gray mapping. Our results show that appropriate code design for higher order constellations reduces the overall bit-error rate. Furthermore, the influence on the UEP capability of the code, that is, the difference in bit-error rate between the protection classes, is investigated.