Unequal Error Protection Using LDPC Codes by Partial Superposition Transmission

In this paper, we present a new approach for unequal error protection (UEP) using low-density parity-check (LDPC) codes by partial superposition transmission (referred to as UEP-by-PST for convenience). The information sequence with two levels of importance is distinguished as two parts, the more important data (MID) and the less important data (LID), both of which are coded with binary LDPC codes. The codeword that corresponds to the MID is superimposed on the codeword that corresponds to the LID. We also investigate the UEP from an information-theoretic point of view. Simulation results show that, over both AWGN channels and uncorrelated Rayleigh fading channels, the UEP-by-PST provides higher coding gain for the MID compared with the traditional equal error protection (EEP) approach, but with negligible performance loss for the LID.