说明：  ：介绍了AWGN 信道基于高阶调制的软解调算法，研究了LDPC 码的和-积译码算法原 理，并对高阶调制的和-积算法及其简化算法进行了研究与性能仿真. 仿真结果表明采用高阶 调制的λ -min 和-积简化算法译码在降低了译码复杂度的同时可实现高速率数据的可靠传输
(the high order soft demodulation algorithms based on AWGN were introduced. Then the basic encoding and decoding principles of LDPC codes were studied, and the sum-product algorithms with its reduced complexity algorithms were presented based on high order soft demodulation. Simulation result shows that the coded-modulation algorithms can work reliably in high speed digital communication.)