It has been reported [Chung01]that a well-designed irregular LDPC code of length 10has the performance within 0.04dB of the Shannon limit at BER=10 d-20 m 10 . 0.05 0.1 015 02 04 05 05 Irregular LDPC Codes,Density Evolution (Chung,Forney,Richardson,Urbanke,2001) For non-binary codes,the coded modulation schemes based on Turbo-like codes can also achieve near capacity performance on both AWGN and fading channels.Fig.4.3 compares the Turbo-TCM scheme to the ti TCM scheme It is se that the improvement made by coding becomes evident.The bit-interleaved coded modulation (BICM)and multilevel coding (MLC)schemes using LDPC codes exhibit similar or even better performance. 4-3 4-3  It has been reported [Chung01] that a well-designed irregular LDPC code of length 107 has the performance within 0.04dB of the Shannon limit at BER=10-6. For non-binary codes, the coded modulation schemes based on Turbo-like codes can also achieve near capacity performance on both AWGN and fading channels. Fig. 4.3 compares the Turbo-TCM scheme to the conventional TCM scheme. It is seen that the improvement made by coding becomes evident. The bit-interleaved coded modulation (BICM) and multilevel coding (MLC) schemes using LDPC codes exhibit similar or even better performance