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针对相位噪声造成的卫星数传系统性能的下降,该文仿真分析了2种不同频段下的相位噪声对于未编码和有低密度奇偶校验(low-density parity-check,LDPC)码的高阶调制系统的影响,并针对较高频段相位噪声造成的编码系统性能的明显下降,提出了一种联合LDPC译码的相位噪声迭代补偿算法。该算法通过对比解调前与译码后符号的相位信息差异,利用相位噪声的窄带低通特性对其进行提取,进而通过构造迭代环路对解调前的符号进行补偿。仿真结果表明:该算法可以有效降低误比特率,对于因相位噪声引起的LDPC编码系统性能的下降有显著的改善作用。
In order to reduce the performance of satellite data transmission system caused by phase noise, this paper simulates the phase noise in two different frequency bands for higher order of uncoded and low-density parity-check (LDPC) codes In order to reduce the performance of coding system caused by phase noise in higher frequency band, a phase noise iterative compensation algorithm combined with LDPC decoding is proposed. By comparing the differences of phase information between pre-decoded and post-decoded symbols, the algorithm extracts the phase noise by using the narrow-band low-pass characteristics of the phase noise, and then constructs an iterative loop to compensate the pre-demodulated symbols. The simulation results show that the proposed algorithm can effectively reduce the bit error rate and significantly improve the performance of LDPC coding system due to phase noise.