中文说明： MAP算法是基于编码网格图的软输出译码算法，目的是使译码输出比特错误概率最小。根据最大似然译码原理，译码器的主要任务就是计算在接收采样条件下，传输符号的概率。而后，将其判决为概率值最大的信息符号。
English Description：
Map algorithm is a soft output decoding algorithm based on coded trellis graph, which aims to minimize the error probability of decoding output bits. According to the principle of maximum likelihood decoding, the main task of the decoder is to calculate the probability of transmission symbol under the condition of receiving sampling. Then, it is judged as the information symbol with the largest probability value.