Optimization and Simulation of Demodulation and Decoding of the LDPC-BICM-ID System

In the bit interleaving coded modulation (BICM-ID) solution,includes the demodulator and decoder into the iteration and decoding process, and the decoding is completed between demodulator and decoder. In studies, it have been found that the oscillation is generated on logarithmic likelihood ratio (LLR) because the soft information generated by all previous BP iterations is ignored in this solution, so that the BP soft information output by the final BP iterative decoding is not always reliable. In this paper, the above problem is solved by optimizing the iterative demodulation and decoding solution. Aiming at this problem, this paper firstly puts forward a kind of optimization scheme about iterative demodulation and decoding, then the simulation analysis, the result show that, under the premise of ensuring the system complexity basically unchanged, can improve the demodulation and decoding performance of LDPC coded modulation and demodulation system.