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采用Imai与Hirakawa提出的多层编码方法可构造出在AWGN信道与Rayleigh衰落信道中好的分组调制 (BCM)码 ,恰当选择成分码可使BCM码有较大的编码增益 .文章对几种BCM码在AWGN及Rayleigh衰落信道中的性能进行了仿真 ,并在这些BCM码之间以及它们与相同频带利用率的未编码系统之间进行了比较 ,结果表明 :在AWGN信道中 ,BCM码较相同频带利用率下的未编码系统有 1～ 3dB的编码增益 ,并且这些编码增益值主要取决于BCM码的最小平方欧氏距离 ;而在Rayleigh衰落信道中 ,编码增益值可达到 6～ 17dB ,决定此值的主要因素为BCM码的汉明距 ,对于BCM码的译码采用多级译码方法
By using the multi-layer encoding method proposed by Imai and Hirakawa, a good BCM code can be constructed in AWGN channel and Rayleigh fading channel, and proper selection of component codes can make the BCM code have larger encoding gain. The performance of the codes in AWGN and Rayleigh fading channels is simulated and compared between these BCM codes and their uncoded systems with the same band utilization. The results show that the BCM codes are the same in the AWGN channel The uncoded system under the band utilization has a coding gain of 1 ~ 3dB, and these coding gains mainly depend on the least square Euclidean distance of the BCM code. In the Rayleigh fading channel, the coding gain can reach 6 ~ 17dB, which determines The main factor of this value is the Hamming distance of the BCM code, and the multi-level decoding method is used for the decoding of the BCM code