分组Turbo码软判决自适应Chase译码算法的研究

针对二进制分组turbo码提出了一种加快译码速度的软判决译码算法-自适应门限Chase译码算法(ATC).该算法以迭代Chase算法为基础,根据传输系统编码方案和信道条件联合确定Chase算法中不可靠比特数,从而可以减少测试序列的数目,并利用外信息的三角函数代替迭代译码时的归一化因子,以达到降低软判决译码复杂度的目的;与迭代Chase译码算法相比,该算法可在译码复杂性和译码性能之间达到平衡.仿真结果表明:ATC算法能在保持turbo码的译码性能基础上,提高译码速度,降低译码复杂度.

Study of Adaptive Chase Algorithm for Block Turbo Codes

A novel soft-decision decoding algorithm, called as adaptive-threshold Chase algorithm (ATC), is proposed. The idea is based on excluding some of the least reliable bits from those be processed according to the Chase algorithm. A relation between the threshold and channel condition is established. The ATC algorithm uses trigonometric function of extrinsic information in stead of the scaling factor. Compared with the iterative Chase algorithm, the proposed algorithm for the binary block turbo code can achieve tradeoffs between decoding complexity and decoding performance. In the experiments, the Hard Decision Decoding numbers are considered as the comparing standard. Simulation results show that the proposed algorithm is faster than the iterative Chase algorithm and has relatively low decoding complexity.