中文摘要：

主要研究在电力线信道下的高阶QAM软信息LDPC解码算法。传统的高阶QAM软信息LDPC算法是基于AWGN信道提出的，若运用在电力线信道中误码率较高。采用MiddletionA类噪声模型来表征电力线信道中的脉冲噪声，针对G．9960协议中的QC-LDPC与高阶QAM软信息进行分析研究，改进现有的M-QAM软信息LDPC解码算法，提出了一种适合电力线信道的高阶调制软信息LDPC解码方法。仿真结果表明改进后的算法误码率更低，相比于传统的高阶软信息算法性能提高2-3dB。

英文摘要：

LDPC （Low-Density Parity Check） decoding algorithm with M-QAM soft demodulation in power line channel is proposed and discussed. The application of traditional algorithm based on AWGN channel to the power line channel would result in high BER. Middletion Class A noise model is applied to reprensenting impulse noise in the power line channel. In accordance with G. 9960 Protocol, a high-order modulation with QC-LDPC as the channel coding is sumulated. Based on the existing soft information LDPC decoding algorithm, a modified high-order modulation LDPC decoding algorithm suitable for power line channel is proposed, and the simulation show that the BER of modified algorithm is lower than that of traditional one, and the transmission performance is significantly improved.