本文利用软输入软输出信道译码器输出对数似然比随相位偏差变化的规律得到低信噪比MPSK信号的 相位偏差代价函数，并提出一种求解该代价函数的迭代相位搜索方法，以相对较小的运算量实现较高精度的相 位估计。仿真表明，该算法在低信噪比下具有稳定的性能，并且能够克服大多相位估计算法都存在的相位模糊 问题。-In this paper, the soft input soft output channel decoder output log-likelihood ratio with the v

This document is about 16 QAM demapping of received data. But its a soft demapping method based Log likelihood ratio(llr). So results can be used as inputs for viterbi decoder or turbo decoder. It is very usefull to decrease BER for communication sys