不规则Qc-LDPC编码在卫星导航系统中的应用研究

Application Research of Irregular Qc-LDPC Codes on Satellite Navigation Systems

LDPC码作为一种接近香农极限的信道编码,近年来被广泛应用于卫星导航及通信领域。现代GPS系统L1C信号的电文已使用码率为1/2的不规则LDPC编码,提升系统的纠错性能。准循环Qc-LDPC编码是一种结构化LDPC码,具有构造简单,译码复杂度低,纠错性能优良等优点。本文对不同长度、不同码率的Qc-LDPC码的两种迭代译码算法的性能进行了仿真研究,研究结果可用于指导不同卫星导航系统导航电文的编译码设计,比如美国的GPS系统、欧洲的Galileo系统和中国的Compass系统。

Low Density Parity Check （LDPC）, as a type of advanced channel codes approaching Shannon limit, has been widely applied in the satellite navigation and communication fields. Modem GPS system has been adopted irregular LDPC codes to enhance the receiving performance of GPS L1C signal. Quasi cyclic-LDPC （Qc-LDPC） codes have the characteristics of simple structure, low decoding complexity and good performance of error correction. In this paper, the performances of two kinds of decoding algorithms of Qc-LDPC codes with different code length and different code rate are compared. The research results can be applied to guide the encoding and decoding design for different satellite navigation systems, such as GPS in USA, Galileo system in Europe and Compass system in China.