LDPC Coded Modulation Schemes with Largely Unequal Error Protection

Coding and modulation schemes able to achieve unequal error protection are of interest for many applications in which parts of the payload must be differently protected against the noise. They are also useful for physical layer security of transmissions over the broadcast channel with confidential messages. Classical design approaches aim at optimizing the performance over all the protection classes, independently of the separation between them. We instead propose a solution to improve the performance over the most protected bits, at the expense of performance over the least protected ones. This allows to design coded modulation schemes with largely unequal error protection. We also consider the use of high order modulations, and propose a technique to study the performance over each protection class in the asymptotic regime of infinite code length.