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针对恶劣环境下接收数据中存在错误而导致喷泉码译码时的误码扩散问题,提出一种具有检错容错能力的LT(Luby transform)码编译码算法。利用LT码编码特点和BP(belief propagation)译码性质,通过对译出源包的冗余校验检出错误的编码包,结合LT码的纠删特性进行正确译码。通过增加少量译码开销,提高了LT码在接收数据错误时的传输可靠性。LT码作为Raptor码的内码,其容错设计可以作为Raptor码容错设计的参考。仿真结果表明:在采用优化度分布函数,包长为250 B,源包个数为512时,该算法可以检出任意数目编码包的错误,检错率达到99.9%以上,并且成功译码时新增译码开销不大于2%。
Aiming at the problem of error code spreading in fountain code decoding when there is an error in the received data under harsh environment, an encoding / decoding algorithm of LT (Luby transform) with error detection and fault tolerance is proposed. By using the coding characteristics of LT code and the BP (belief propagation) decoding property, the error code package is detected by the redundant verification of the translated source packet, and the correct decoding is performed according to the erasure correction characteristics of the LT code. By adding a small amount of coding overhead, the LT code improves the reliability of the transmission when receiving data errors. LT code as the inner code of Raptor code, its fault-tolerant design can be used as Raptor code fault-tolerant design reference. The simulation results show that the proposed algorithm can detect errors of any number of encoded packets when the packet length is 250 B and the number of source packets is 512, and the error detection rate reaches more than 99.9%. When the decoding is successful New decoding cost is not more than 2%.