天基信息传输高效低复杂度 LDPC 译码算法研究

Military satellite communication is required to fulfill the need of real-time information transmission, high transmission rate, large communication capacity and adaptability to the time-varying characteristics of inter-satellite links, so the channel coding schemes with high coding gain and high throughput are adopted. Low-density parity-check (LDPC) code has become one of the main channel coding standards for its excellent error-correction performance which can approximately achieve the Shannon limit and its parallel computing capability. However, there are still some problems in its decoder module design of satellite communication receiver, such as failure of real-time online stopping judgement on iterative decoding, limited system throughput, and excessive decision circuits that reduce the power and real-time performance of decoding circuit. This paper adopts the CCSDS coding standards for deep space communication, and proposes the design of an iterative decoding stopping criterion algorithm based on a factor graph model. The algorithm tightly couples the evolution of normalized syndrome satisfaction probability with the state of LDPC decoder, so as to achieve high performance and low complexity. The results show that, when high throughput is preferentially considered, the bit error rate (BER) performance is degraded by 0. 13 dB, and meanwhile the average number of iterations (ANI) in medium and low SNRs is reduced by more than 50%; when error-correcting performance is preferentially considered, BER performance is only degraded by 0. 02 dB. Whereas, the ANI is greatly reduced. The proposed algorithm serves as an effective solution for the design of low complexity and high efficiency LDPC decoder.