A new soft decision metric for QAM is presented in this paper.Unlike traditional soft decision metric based on minimum Euclidean distance, the proposed metric is based on the bit confidences.

• 传统的软判决度量大多是基于最小欧氏距离准则生成，该文提出一种基于比特置信度快速生成QAM软判决度量的算法，通过将比特置信度引入到QAM软判决度量的计算中来减少计算的复杂性。