Mapping Strategies And Performance Analysis In LDPC Coded BICM And BICM-ID Systems

Low-Density Parity-Check (LDPC) coded Bit-Interleaved Coded-Modulation (BICM) system and its iteration version (BICM-ID) have been extensively investigated due to flexible structure, high band-width efficiency and excellent decoding performance. This thesis focuses on the design of mapping strategies in LDPC coded BICM and BICM-ID schemes and launch mapping performance analysis based on Extrinsic Information Transfer Chart.It's found that the overall performance of modulation in these systems depends not merely on the constellation and the map from bits to symbols, but also the code used and the decoding strategy. The design criterions proposed previously based on Euclidean distance that only take constellation and labeling into consideration will be challenged. The newly proposed bit mutual information proves to be a more accurate tool. To obtain "the-best-mapping" by maximizing the HMMSE value, promising mapping such as Swap and Nature are easily generated by swapping operation originally from Gray mapping. Under the help of bit mutual information design rule, "the-best-mapping" in 16QAM and 64QAM are found and the system performance is improved significantly with no added complexity.In order to provide a more comprehensive fashion to interpret the specificity of mapping design, EXIT chart for high-ary modulated BICM system is introduced. According to the variable node decoder information updating difference, EXIT chart under the conditions of non-BPSK modulated channel is developed and improved, which can help to evaluate mapping performance efficiently.