一种新的WIMAX标准LDPC码的软判决译码算法

摘要

WIMAX standard LDPC is based on quasi-cyclic encoding, and the decoding usually uses the sum-product decoding algorithm. In order to further reduce decoding complexity, a novel modified normalized min-sum (NMS) algorithm is proposed in this paper. The optimal multiplicative factor is obtained by a lot of simulation samples and analyses, and the approximate linear formula is deduced as well. On the basis of it, combining with the check node degree-matched algorithm, the decoding performance is improved further. Simulation results indicate that the proposed novel algorithm improves the decoding performance greatly compared with the NMS algorithm, the offset min-sum (OMS) algorithm and check node degree-matched (CNM) algorithm, and the BER is very close to the sum-product algorithm.%WIMAX 标准下的 LDPC 码采用准循环编码方式，其译码多为和积（SP）译码算法。为了进一步降低译码复杂度，通过大量仿真分析获得最优乘性因子的值，并推导出近似线性公式，提出了一种改进型的归一化最小和(MNMS)算法。在此基础上，与校验节点匹配(CNM)算法相结合，进一步提高译码性能。仿真结果表明，这种新算法相比归一化最小和(NMS)算法、抵消最小和(OMS)算法、校验节点匹配(CNM)算法，其译码性能有明显改善，性能几乎接近和积（SP）译码算法。