Performance Analysis of LDPC-BICM System Based on Gaussian Approximation

In this paper, we propose a performance analysis algorithm of low density parity check-bit interleaved coded modulation (LDPC-BICM) system. First, we introduce the Gaussian mixture approximation method of the LLR messages output from the demodulator over the AWGN channel. Then, we analyze the density evolution based on these Gaussian mixture approximation LLR messages. During the analysis, the Gaussian approximation is applied to simplify the calculation. Some LDPC-BICM systems (which are adopted by ATSC3.0 standard) are used to evaluate the proposed algorithm. We also employ the actual performances and the thresholds obtained by the multi-edge type (MET) discretized density evolution algorithm as the references. The simulation results prove that our proposed algorithm can work well in most cases. Furthermore, the proposed algorithm is simpler than the MET algorithm because of the Gaussian or Gaussian mixture approximations.