Design and Performance Evaluation for BILCM-ID System With Improved Stopping Criterion

Low-density parity-check (LDPC) codes characterize both a relatively low decoding complexity and a performance nearing the Shannon limit. The integration of channel coding with modulation, known as bit-interleaved coded modulation (BICM), is widely utilized in communication and broadcasting systems. In particular, iterative message passing processes between soft demapper and decoder have proven effective in improving the bit error rate (BER) performance in the bit-interleaved LDPC coded modulation with iterative decoding (BILCM-ID) systems. This study proposes a novel approach for representing the iterative state in the probability domain for high-order modulation within the BILCM-ID process. Additionally, our methods introduce an improved stopping criterion based on the normalized belief evolution pattern (NBEP). Simulation analyses demonstrate that, compared to conventional hard-decision methods, the proposed algorithm can reduce ineffective iteration delay by approximately 88% with negligible degradation in BER performance.