基于纠删码的遥测链路丢帧恢复技术

针对遥测系统在恶劣天气条件、航天器姿态调整、天线指向偏离、脉冲干扰等各种因素影响下出现的遥测信号闪断以至接收机丢帧问题,提出一种适用于闪断信道的纠删码技术,用于恢复丢失的数据帧.首先介绍LDPC（低密度奇偶校验）纠删码的编译码算法,然后构造一种以短码长的随机码为外码、IRA（不规则重复累积）LDPC码为内码的级联纠删码,最后给出纠删码的应用策略和实现纠删码所需的CCSDS（空间数据系统咨询委员会）协议扩展.通过仿真实验和分析,得到了LDPC纠删码和级联纠删码的纠删性能,得出级联纠删码与LDPC纠删码均可获得接近理想的纠删性能的结论,且级联纠删码的构造更为灵活,可适应不同的应用环境,对CCSDS协议进行适当扩展后即可支持纠删码在CCSDS遥测链路中的应用.

Erasure Correction Codes for Frame Loss Recovery in Telemetry Links

An erasure correction code is proposed to recover frame loss because of signal discontinuity caused by factors such as adverse weather,spacecraft attitude adjustment,antenna pointing error and pulse interference.Following introduction of encoding/decoding algorithm of erasure correction LDPC （Low Density Parity Check） codes,a concatenated code composed of a short random outer code and an IRA （Irregular Repetitive Accumulation） LDPC in ner code are constructed.Possible coding strategies and CCSDS （Consultative Committee for Space Data Systems）protocol extensions for implementation of erasure correction codes are presented.The performance of erasure correction LDPC codes and concatenated codes are obtained through simulation and the results show that near-optimum erasure correction performance is achieved.The proposed codes can be designed with high flexibility and is applicable to a variety of application scenarios after making necessary CCSDS protocol extensions.