对两种次最佳软输入软输出译码算法（简化的最小误符号率（ＢＣＪＲ）和软输出维特比算法（ＳＯＶＡ））的优缺点进行简要比较分析，并就进一步简化ＢＣＪＲ 算法作了探讨．导出了以减少单步译码运算量为目的的两种简化算法递推公式；提出了一种更具一般性的活动窗ＢＣＪＲ算法实现方案．该方案用于级联码的迭代译码，通过适当调整活动窗参数，在尽可能降低算法复杂度的同时，获得与基于非活动窗ＢＣＪＲ算法时几乎相同的误比特性能 The advantages and disadvantages of two sub-optimal soft-input soft-output decoding algorithms (simplified minimum symbol error rate (BCJR) and soft-output Viterbi algorithm (SOVA)) are compared and analyzed, and further simplified BCJR algorithm is discussed . Two simplified algorithm recursion formulas are proposed to reduce the computation amount of single-step decoding. A more general implementation scheme of BCJR for active window is proposed. The scheme is used for iterative decoding of cascaded codes. By adjusting the parameters of the active window, the proposed scheme can reduce the complexity of the algorithm as much as possible, and obtain almost the same bit error performance as the BCJR algorithm based on the non-active window