喷泉码的编译码算法及应用研究

发布时间：2018-03-18 23:00

本文选题：喷泉码　切入点：LT码　出处：《中国矿业大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着无线通信系统的快速发展,用户对信息传输的可靠性提出了更高的要求。喷泉码作为一种基于删除信道的信道编码技术,被广泛应用于可靠广播传输场景中。其采用了随机编码的思想,具有无固定码率、鲁棒性、高效性、较低的编译码复杂度、无需反馈信道来确保传输的可靠性和适应实时变化的信道等优点。然而喷泉码作为一种依据某种启发思想设计出来的信道编码技术,其度分布函数和编译码算法仍然具有很大的改进空间。本文以喷泉码技术为主体,针对喷泉码的译码效率低、编码矩阵不满秩以及应用场景问题,研究了喷泉码的度分布算法、编译码算法及可靠传输方案。主要研究工作如下:第一,针对喷泉码较低的译码效率问题,MBRSD度分布算法通过控制度为1编码包的连接方式优化了平均可译集大小从而减少了译码时间。由于该算法中缺少度为1的编码包且其分布不均匀,通过把增加度为1的编码包的插值算法与MBRSD度分布算法相结合,本文提出了IMBRSD度分布算法。改进的算法减少了成功译码需要的编码包数,并且降低了系统的误码率。第二,针对喷泉码编码矩阵存在的不满秩情况会导致接收端无法正确译码的问题,本文在发送端对编码矩阵进行了满秩矩阵预处理。其通过对编码矩阵进行增广矩阵处理,选出少量列向量补充到原编码矩阵中来构成满秩矩阵。本文提出的编码矩阵满秩优化算法降低了喷泉码译码失败概率。第三,针对固定码率无法匹配实时变化的信道容量问题,本文将满秩优化后的喷泉码应用在广播传输方案中从而解决了不可靠传输问题。发送端依据接收端反馈的正确译码包的数目计算实际信道的删除概率,然后根据实际信道条件调整编码包输出个数。该传输方案可以减少反馈信道带来的能量消耗并且能够自适应地实现码率与时变信道容量的匹配,增加了广播的可靠性。
[Abstract]:With the rapid development of wireless communication system, users put forward higher requirements for the reliability of information transmission. Fountain code is a channel coding technology based on deleted channel. It is widely used in reliable broadcast transmission scenarios. It adopts the idea of random coding and has no fixed code rate, robustness, high efficiency, low encoding and decoding complexity. There is no need for feedback channels to ensure the reliability of transmission and the advantages of adapting to real-time changing channels. However, fountain code is a channel coding technique designed according to some heuristic idea. The degree distribution function and the encoding and decoding algorithm still have a great improvement space. In this paper, the fountain code is used as the main body. In view of the low decoding efficiency of the fountain code, the rank of the coding matrix and the application scene, the degree distribution algorithm of the fountain code is studied. Coding and decoding algorithms and reliable transmission schemes. The main research work is as follows: first, In order to solve the problem of low decoding efficiency of fountain codes, the MBRSD distribution algorithm optimizes the average translatable set size by controlling the connection of coding packets with a degree of 1, thus reducing the decoding time. Due to the lack of coded packets with degree 1 in the algorithm, the decoding time is reduced. And its distribution is uneven, By combining the interpolation algorithm with the MBRSD degree distribution algorithm, an improved IMBRSD degree distribution algorithm is proposed. The improved algorithm reduces the number of coding packets required for successful decoding and reduces the bit error rate (BER) of the system. In view of the problem that the incomplete rank of the fountain code coding matrix will cause the receiver to be unable to decode correctly, this paper preprocesses the full rank matrix of the code matrix at the sending end. A small number of column vectors are selected to add to the original coding matrix to form the full rank matrix. In this paper, the full rank optimization algorithm of the coding matrix reduces the decoding failure probability of fountain code. Thirdly, for the channel capacity problem in which the fixed code rate can not match the real-time variation, In this paper, the full rank optimized fountain code is applied to the broadcast transmission scheme to solve the unreliable transmission problem. The sender calculates the deletion probability of the actual channel according to the number of correct decoding packets feedback from the receiver. Then the output number of coding packets is adjusted according to the actual channel conditions. The proposed scheme can reduce the energy consumption brought by the feedback channel and adaptively match the code rate with the time-varying channel capacity and increase the broadcast reliability.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN911.22

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