高性能准循环低密度奇偶校验码在导航信号中的应用

全球定位系统(GPS)在其现代化计划中选择低密度奇偶校验(LDPC)码作为其将来的L1C电文的信道编码方案，能够获得优异的译码性能，但复杂度也相对提高，所采用随机LDPC码的编码器和解码器的硬件实现较为困难。在802.16e协议中提出的LDPC码的基础上，提出一种增强型的准循环低密度奇偶校验(QC-LDPC) 码，其校验矩阵同时具有准循环结构和近似下三角结构，且最小圈长为8，克服了随机LDPC码的缺点。仿真结果表明，所构造的QC-LDPC码性能优于802.16e协议中的LDPC码和GPS L1C电文中采用的LDPC码，对我国“COMPASS”导航系统的信道编码方案具有参考价值。

Application of quasi-cycle low-density parity check codes with high performance to satellite navigation signals

In the Global Positioning System (GPS) modernization plan, Low-Density Parity Check (LDPC) code is used for the channel coding scheme of L1C signals, which brings out excellent decoding performance, but higher complexity. The encoder and decoder of random constructed LDPC codes are difficult to implement with Very Large Scale Integration （VLSI）. A kind of enhanced Quasi-Cycle LDPC (QC-LDPC) codes based on LDPC codes was proposed, which had both quasi-cycle structure and approximate lower triangular form. The girth of the proposed codes is 8. The simulation results show that QC-LDPC codes are superior to LDPC codes used in 802.16e and GPS L1C signals, and it is helpful to the development of new signal scheme of COMPASS navigation system.