16QAM因其高频谱利用率而被第三代移动通信增强型技术HSDPA采用。由于Turbo译码需要软信息输入，因此，解调输出需要计算比特软信息（LLR）。本文分析了LLR理论算法并在此基础上导出了简化算法。-16QAM its high spectral efficiency have been enhanced third-generation mobile communication technology HSDPA use. Turbo decoding requires soft information as input, therefore, need to compute soft output demodulation information (LLR). This paper analyzes the LLR theory based on the algorithm derived in this simplified algorithm.