Research on Performance of LDPC Coded BICM Schemes Using Pre-decision Message

Low-Density Parity Check(LDPC) coded Bit-Interleaved Coded Modulation (BICM) schemes are analyzed in this paper. The schemes using decoding method without iteration between demodulator and decoder are first simulated. Then a novel method using pre-hard-decision message is proposed. And the performance over Additive White Gaussian Noise (AWGN) and Rayieigh fading channels is analyzed. The decoding complexity is also considered. The new method proves that the conventional bit-metrics generation method is not optimal. Through the simulation results there is conclusion that the proposed schemes have better performance than the scheme without pre-decision message both over AWGN and Rayieigh fading channels with nearly same complexity.