次最佳软输入软输出译码算法

对两种次最佳软输入输出译码算法（简化的最小误符合率（ＢＣＪＲ）和软输出维持比算法（ＳＯＶＡ）的优缺点进行简化比较分析，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。

Sub-Optimal Soft-In-Soft-Out Decoding Algorithms

For practical implementation, there have been various simplified Bahl Cocke Jelinek Raviv(BCJR) algorithms and other sub optimal decoding algorithms such as soft output viterbi algorithm(SOVA). This paper presented a comparative analysis of these sub optimal algorithms. Going further into the problem about the simplification of the BCJR algorithm, it derived a more simplified recursive formulae to reduce its decoding operation for each bits. Finally, it proposed a more general scheme of sliding window BCJR algorithm. Using this modified BCJR algorithm to implement iterative decoding of concatenated codes, by adjusting its sliding window parameters, it can reduce the complexity of the algorithm as much as possible meanwhile the BER performance of the concatenated codes nearly remains the same as the decoding scheme based on the non sliding window BCJR algorithm.