一种近联合界北斗B1I信号BCH码译码算法

提出一种性能接近联合界的北斗B1I信号BCH码译码算法. 以北斗卫星导航系统B1I公开服务信号ICD为基础,分析导航电文的BCH(15,11)编码的纠错能力和联合界,针对ICD标准译码算法的编码增益低和译码失败门限高提出改进算法. 以Chase算法为基础提出一种新的BCH编码软判决译码算法,使用格雷码排序优化伴随式计算,证明最大相关性与最小欧氏距离的等价关系,优化算法在不损失编码增益的条件下复杂度降低50%. 仿真结果表明在误码率10-5时距离联合界仅0.01 dB,新算法可获得2.5 dB的编码增益,译码失败门限从4.4 dB下降到1.2 dB. 

A Near Union Bound Decoding Algorithm for BCH Code of Beidou B1I Navigation Signal

A near union bound decoding algorithm for BCH code of Beidou B1I navigation signal was proposed. The error correlation capability and union bound of BCH (15, 11) was established, which is accordant to Beidou B1I open service signal ICD file. An improved decoding algorithm was designed to overcome the low coding gain and high decoding fail threshold of standard decoding algorithm in ICD file. The new soft-decision decoding algorithm was considered based on Chase algorithm. The complexity of syndromes computing was reduced based on Gray code ordering in test code set. The equivalence of maximum correlation and minimum Euclidean distance was proved. The complexity of optimized soft-decision decoding algorithm reduces 50% without coding gain lost. Simulation results indicate that the different of union bound and the proposed scheme less than 0.01 dB at BER=10^-5. More than 2.5 dB coding gain is provided by the new decoding algorithm and the decoding failure threshold decreases from 4.4 dB to 1.2 dB.