该文在研究TURBO 码反向SOVA(SOFT－OUTPUT VITERBIALGORITHM )译码性能的基础上,提出了一种同时利用正向和反向SOVA译码软输出信息的基于SOVA 的改进译码结构及其相应的软输出修正公式.计算机模拟结果表明,所提出的改进方案与传统的SOVA算法相比,其译码性能有明显的改善,并略优于MAX－LOG－MAP的性能“,”Based on studying the decoding performance of parallel concatenated convolutional(turbo)codes(PCCCs)by using SOVA with backward recursion(B SOVA),an improved SOVA based decoding structure and a revised formula of soft output involved are proposed in this paper,in which the soft output information of B SOVA combined with that of SOVA(with forward recursion,as normal)is considered.The computer simulation results show that the decoding performance of the proposed scheme is obviously improved compared with that of the normal SOVA and is even slightly superior to that of Max Log MAP.