Abstract: As the new generation communication system, LTE/LTE-A requires reliable communication of higher standard for its high-throughput characteristic. Among those decoding algorithms of Turbo, Log-MAP algorithm, as a simplified algorithm, has a good performance, but its high complexity and delay is still a big problem; Max-Log-MAP algorithm with low complexity could not achieve a good performance as the Log-MAP algorithm. This paper proposed an improved Turbo decoding algorithm based on a linear approximation of the correction function. The improved algorithm adopted different correction fitting parameters for different regions. The simulation results demonstrate that, compared with the existing algorithms, this improved algorithm can achieve the same Bit Error Rate (BER) performance as the Log-MAP algorithm and effectively reduce the decoding delay. More importantly, the proposed algorithm is better for implementation.

Key words: Turbo code, Log-Map, Max-Log-MAP, decoding delay, correction function, linear approximation

摘要： 新一代移动通信系统LTE/LTE-A具有高吞吐率的突出特点和需求，但高速译码也对误码率和延时等提出了更高的要求。现有的Turbo码译码算法中，Log-MAP算法译码性能较好，但算法复杂度高，时延大;而Max-Log-MAP算法虽然具有较低的复杂度，但译码性能较差。为此，提出一种基于修正函数线性拟合的Turbo译码算法，该算法针对不同刻度区间采用不同的拟合参数。实验仿真表明，该算法与现有算法比较，能够达到Log-MAP算法的译码性能，且避免了Log-MAP的大量运算，从而在保证较好译码性能的基础上，有效地降低了译码延时，并且便于硬件实现。

关键词: Turbo码, Log-Map, Max-Log-MAP, 译码延时, 修正函数, 线性拟合