共查询到19条相似文献,搜索用时 171 毫秒
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当通信系统允许反馈时,除用反馈控制信息的传输外,还可用于调整喷泉码的编码,提高整体的编译码性能。文章针对Raptor码的码长分别为短码和中长码时,研究如何利用反馈来调整Raptor码的编码算法,并给出了两种不同的编码算法。仿真结果表明,与原来的编码算法相比,提出的两种算法均明显减小了译码开销,提高了译码效率。 相似文献
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Fountain码编译码技术的研究 总被引:2,自引:2,他引:0
通过从Fountain码的其中一种LT码的度数分布入手进行分析,发现LT码易出现停止集.针对LT码的缺点分别将汉明码和RS码作为Fountain码的预编码对其进行了改进并仿真.仿真结果证明预编码可以降低停止集出现的概率.通过对Hamming-Founta in码和RS-Fountain的仿真对比表明RS-Fountain码具有更高的恢复能力. 相似文献
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LDPC码BP译码算法研究 总被引:1,自引:0,他引:1
本文研究了LDPC码的译码。深入研究了概率域BP算法和LLRBP算法。通过计算机仿真,比较了不同码长和不同迭代次数对译码性能的影响。通过计算机仿真得到在LDPC译码过程中,LDPC码的码字越长,构造的校验矩阵中短周期就越短,性能提高就越为明显。同时得到在LDPC译码过程中,迭代次数越多,各节点获得的信息的准确性就越高,性能提高就越为明显。 相似文献
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度分布是影响Luby变换(Luby transform,LT)码性能优劣的关键因素,为了得到更优的度分布,提出一种基于改进的二进制指数分布(improved binary exponential distribution,IBED)和仿生算法的LT码度分布设计方案.采用IBED度分布进行LT编码,初始译码成功率可高达90%以上,但随着译码开销增大,译码成功率上升速度减缓,而此时鲁棒孤子分布(robust soliton distribution,RSD)的译码性能表现更佳.为了将IBED和RSD的优点有机结合,利用人工鱼群算法(artificial fish swarm algorithm,AFSA)在两种度分布间寻优,基于期望可译集构建该算法的目标函数,通过最大化目标值得到更优的度分布.仿真结果表明,与类似方法及传统的RSD相比,采用新度分布进行LT编码可明显降低译码开销,并节约编译码耗时. 相似文献
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This paper presents a two-stage turbo-coding scheme for Reed-Solomon (RS) codes through binary decomposition and self-concatenation. In this scheme, the binary image of an RS code over GF(2/sup m/) is first decomposed into a set of binary component codes with relatively small trellis complexities. Then the RS code is formatted as a self-concatenated code with itself as the outer code and the binary component codes as the inner codes in a turbo-coding arrangement. In decoding, the inner codes are decoded with turbo decoding and the outer code is decoded with either an algebraic decoding algorithm or a reliability-based decoding algorithm. The outer and inner decoders interact during each decoding iteration. For RS codes of lengths up to 255, the proposed two-stage coding scheme is practically implementable and provides a significant coding gain over conventional algebraic and reliability-based decoding algorithms. 相似文献
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Probabilistic algorithms are given for constructing good large constraint length trellis codes for use with sequential decoding that can achieve the channel cutoff rate bound at a bit error rate (BER) of 10-5-10-6. The algorithms are motivated by the random coding principle that an arbitrary selection of code symbols will produce a good code with high probability. One algorithm begins by choosing a relatively small set of codes randomly. The error performance of each of these codes is evaluated using sequential decoding and the code with the best performance among the chosen set is retained. Another algorithm treats the code construction as a combinatorial optimization problem and uses simulated annealing to direct the code search. Trellis codes for 8 PSK and 16 QAM constellations with constraint lengths v up to 20 are obtained. Simulation results with sequential decoding show that these codes reach the channel cutoff rate bound at a BER of 10-5-10-6 and achieve 5.0-6.35 dB real coding gains over uncoded systems with the same spectral efficiency and up to 2.0 dB real coding gains over 64 state trellis codes using Viterbi decoding 相似文献
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传统的简单级联编码调制系统在译码时会造成软信息损失.提出了一种基于MSK和LT码的联合软迭代译码算法,设计了算法的系统模型.利用LT码的软译码和MSK调制的SISO算法,进行联合软迭代译码,提高了编码调制系统的性能.仿真结果表明:在误码率为10-4时,提出的算法比传统的简单级联编码调制算法约有1.5 dB的编码增益. 相似文献
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Sang‐Hyo Kim Hosung Park Jong‐Seon No Dong‐Joon Shin 《International Journal of Communication Systems》2013,26(11):1475-1484
Under severely unreliable channel, decoding of error‐correcting codes frequently fails, which requires a lot of computational complexity, especially, in the iterative decoding algorithm. In hybrid automatic repeat request systems, most of computation power is wasted on failed decoding if a codeword is retransmitted many times. Therefore, early stopping of iterative decoding needs to be adopted. In this paper, we propose a new stopping algorithm of iterative belief propagation decoding for low‐density parity‐check codes, which is effective on both high and low signal‐to‐noise ratio ranges and scalable to variable code rate and length. The proposed stopping algorithm combines several good stopping criteria. Each criterion is extremely simple and will not be a burden to the overall system. With the proposed stopping algorithm, it is shown via numerical analysis that the decoding complexity of hybrid automatic repeat request system with adaptive modulation and coding scheme can be fairly reduced. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Results on the Improved Decoding Algorithm for Low-Density Parity-Check Codes Over the Binary Erasure Channel 总被引:1,自引:0,他引:1
Vellambi B.N. Fekri F. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2007,53(4):1510-1520
In this correspondence, we first investigate some analytical aspects of the recently proposed improved decoding algorithm for low-density parity-check (LDPC) codes over the binary erasure channel (BEC). We derive a necessary and sufficient condition for the improved decoding algorithm to successfully complete decoding when the decoder is initialized to guess a predetermined number of guesses after the standard message-passing terminates at a stopping set. Furthermore, we present improved bounds on the number of bits to be guessed for successful completion of the decoding process when a stopping set is encountered. Under suitable conditions, we derive a lower bound on the number of iterations to be performed for complete decoding of the stopping set. We then present a superior, novel improved decoding algorithm for LDPC codes over the binary erasure channel (BEC). The proposed algorithm combines the observation that a considerable fraction of unsatisfied check nodes in the neighborhood of a stopping set are of degree two, and the concept of guessing bits to perform simple and intuitive graph-theoretic manipulations on the Tanner graph. The proposed decoding algorithm has a complexity similar to previous improved decoding algorithms. Finally, we present simulation results of short-length codes over BEC that demonstrate the superiority of our algorithm over previous improved decoding algorithms for a wide range of bit error rates 相似文献
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An algorithm for decoding Turbo codes that combines conventional Turbo decoding and list sequence maximum a posteriori probability decoding is presented and evaluated. Compared to previous results on this theme, performance improvements in the order of 0.7 dB are obtained for Turbo codes with 514-b pseudorandom interleaving at a frame error rate of 10/sup -4/ on the additive white Gaussian noise channel. 相似文献
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对信源信道自适应联合编码方法进行了研究,提出了一种新的基于纠错算术码的联合信源信道编解码系统。该系统在编码端利用算术码内嵌禁用符号实现信源信道一体式编码,即利用马尔科夫信源模型和根据信道状态信息自适应地调整禁用符号概率大小从而调整编码码率来实现信道自适应;在解码端,推导出了基于MAP的解码测度数学公式并基于此测度公式提出了一种改进的堆栈序列估计算法。与传统的信道自适应编码算法不同,该自适应编码算法只需调整一个参数:禁用符号,且理论上可获得连续可变的编码码率。实验结果表明,与经典的Grangetto联合编码系统以及分离编码系统相比,所提出的编码系统具有明显改善的性能增益。 相似文献
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In this letter, we propose a new decoding algorithm to improve the bit error rate performance of the hard-input hard-output (HIHO) turbo product codes (TPC) with hard iterative decoding. The proposed algorithm iteratively, but not sequentially, decodes the received TPC blocks based on the reliability of the constituent codes. Simulation results confirm a noticeable coding gain improvement using the proposed decoding process with respect to standard HIHO TPC decoding. An efficient implementation of the new technique offers a negligible additional complexity when the channel-bit error probability is less than 10?2. 相似文献