卢比变换(LT)码是第一种具有实用价值的数字喷泉码。LT码在噪声信道中具有良好的性能, 且已在自由空间光通信(FSO)中广泛应用。文章首先简要说明了LT码的基本原理, 列举了LT码与其他几种FSO中常用的编码方案的优缺点。然后, 概括了国内外对LT码在FSO系统中应用的研究进展, 并从新型度分布和改进的译码方案两个角度详细介绍了LT码在FSO系统中应用的性能优化方案。最后, 指出了现有LT码相关研究的不完善之处, 对LT码在FSO中的未来研究方向提出了展望。

The Luby Transform (LT)codes is the first digital fountain codes that has practical values. LT codes can demonstrate excellent performance in noisy channels, and it has been widely applied in Free Space Optical Communications (FSO). In this article, the basic principle of LT codes is introduced, and the advantages and disadvantages of LT codes and other common encoding schemes for FSO are listed. Besides that, the progress of both domestic and foreign researches on the applications of LT codes in FSO systems is summarized. Then, the strategies for enhancing the performance of LT codes in FSO systems are elaborately described in two aspects, i.e., novel degree distributions and improved decoding schemes. Finally, the incompletions of the existing researches on LT codes are indicated, and some directions of further researches on LT codes in FSO are depicted.