深空通信中Ka频段自适应纠删编码研究

摘要

未来深空通信将采用Ka频段进行深空探测任务,但余量有限的Ka频段链路受地面站区域天气的影响较大,容易产生中断.将Ka频段链路的噪声温度建模为两状态马尔科夫链的Gilbert-Elliot信道,结合异步CFDP传输模式,设计了低误差的天气状态预测模型,同时针对给定噪声阈值下天气状态转换对下行链路丢包率的影响,提出一种基于天气状态转换的RS码与弱鲁棒孤波分布LT码级联的分组纠删编码技术,通过预测模型实现自适应码率调整以保持Ka频段的数据链路连续性以及有效吞吐量.仿真表明算法可实现对数据分组的纠删保护,提高接收端的译码性能,增大系统吞吐量,提高文件传输效率.%Deep-space communication will employ Ka-band for future exploration missions. While the Ka-band links with limited margin, it is much more susceptible to fluctuating weather conditions of ground station area, thus leading to interrupt easily. A low-error weather state forecast model is designed by combining a two-state Markov Gilbert-Eliot channel for the noise temperature and CCSDS File Delivery Protocol (CFDP) Asynchronous NAK mode. Considering the different downlink' s packet loss rate in two states separated by the noise temperature threshold, a packet erasure concatenated coding scheme composed of RS code and LT code with Weaken Robust Soliton Distribution (WRSD) is proposed. The coding scheme is capable to adapt code rate to maintain the Ka-band link continuity and effective throughput. Simulation results show that the algorithm can recover erasure packets, enhance decoding performance, increase system throughput and improve transmission efficiency.