共查询到17条相似文献,搜索用时 203 毫秒
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利用现场可编程门阵列(FPGA,Field Programmable Gate Array)实现了一种基于深空通信的级联码结构。该级联码包括内码和外码,内码是基于全并行的软判决Viterbi译码器结构,用来纠正随机错误,结合帧同步技术完成解交织,然后进行外码里德-所罗门码(RS codes,Reed-solomon codes)译码,纠正突发错误,实现级联码译码。通过实际硬件测试,在满足系统误码率要求的前提下,使用该级联码译码器能够降低发射功率或减少天线尺寸,对降低系统成本及提高系统性能具有非常重要的作用。 相似文献
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光通信中基于BCJR的BCH译码算法研究 总被引:1,自引:1,他引:0
首先从理论上分析了硬判决译码算法和软判决译码算法的性能然后对BCH(Bose,Ray-Chaudhuri,Hocquenghem)码的网格结构以及BCJR(Bahl,Cocke,Jelinek and Raviv)算法进行了详细地分析及推导。实验结果表明,在光信道环境中,在误比特率为10-5时,当仅提高最小汉明距离码率相同或者仅减小码率最小汉明距离相同时,BCJR算法相对于硬判决译码算法的编码增益分别在之前的编码增益基础上又增加了0.15dB和0.25dB。因此设计级联码方案时,应尽可能选择纠错能力较大的内码。此外也可以采用适当增加内码的冗余度相应减小外码的冗余度的方法,在获得更高的编码增益的同时保证整个系统的带宽利用率不变。 相似文献
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针对短码长LT码(码长在103以下)的随机编码方式,需要较高的编码冗余才能保证一定的译码性能的问题。设计了一种基于限制Tanner图连接边随机关系的随机置换展开编码算法,可以实现在较小编码冗余开销下提高短码长LT码的可译码概率。在此基础上,针对短码长LT码的传统BP译码算法效率不高的问题,充分利用BP算法译码失败的停止集剩余信息,设计了采用上述编码算法的短码长LT码的停止集高斯译码算法,可以获得接近最大似然译码的性能。仿真结果表明,所提出的编译码联合算法有效降低了短码长LT码满足10 4译码失败概率时所需的编码冗余开销。 相似文献
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LDPC编码调制系统中基于反馈LLR均值的迭代解调/译码算法 总被引:1,自引:0,他引:1
该文针对LDPC码编码的BICM系统,提出一种对LDPC码译码器输出外附信息的计算方法进行改进的迭代解调/译码算法。与传统的解调/译码算法不同在于,该算法对每次BP迭代中译码器输出的各编码比特的外附LLR分别求均值后,再将其作为先验信息反馈给软解调器开始下次的迭代解调/译码。采用该方法可有效地减轻LDPC码在BP迭代过程中某些比特LLR值的振荡现象,从而使得传递给软解调器的外附信息更准确。仿真结果表明,和传统的两种迭代解调/译码算法相比,该算法能进一步提高LDPC编码BICM迭代系统的译码性能,而复杂度并无明显增加。 相似文献
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根据BP译码算法,设计了一种高速部分并行QC_LDPC码译码器结构,该结构适用于所有其校验矩阵具有准循环特性的LDPC码.针对传统BP译码器的结构复杂度高,系统运行频率低和吞吐率小等特点,本设计将BP译码算法中大量的复杂函数运算通过查找表的方法来实现;校验节点和变量节点的处理均采用5级流水线的方式;采用提前终止迭代译码策略.本设计能有效地减少译码器硬件实现复杂度,同时提高系统运行地频率和数据吞吐率. 相似文献
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A neural network (NN)-based decoding algorithm of block Markov superposition transmission (BMST) was researched.The decoders of the basic code with different network structures and representations of training data were implemented using NN.Integrating the NN-based decoder of the basic code in an iterative manner,a sliding window decoding algorithm was presented.To analyze the bit error rate (BER) performance,the genie-aided (GA) lower bounds were presented.The NN-based decoding algorithm of the BMST provides a possible way to apply NN to decode long codes.That means the part of the conventional decoder could be replaced by the NN.Numerical results show that the NN-based decoder of basic code can achieve the BER performance of the maximum likelihood (ML) decoder.For the BMST codes,BER performance of the NN-based decoding algorithm matches well with the GA lower bound and exhibits an extra coding gain. 相似文献
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Lin-Nan Lee 《Communications, IEEE Transactions on》1977,25(10):1064-1074
Concatenated coding systems utilizing a convolutional code as the inner code and a Reed-Solomon code as the outer code are considered. In order to obtain very reliable communications over a very noisy channel with relatively modest coding complexity, it is proposed to concatenate a byte-oriented unit-memory convolutional code with an RS outer code whose symbol size is one byte. It is further proposed to utilize a real-time minimal-byte-error probability decoding algorithm, together with feedback from the outer decoder, in the decoder for the inner convolutional code. The performance of the proposed concatenated coding system is studied, and the improvement over conventional concatenated systems due to each additional feature is isolated. 相似文献
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W. H. Ng J. L. Ungar 《International Journal of Satellite Communications and Networking》1993,11(2):53-61
Signal editing (SE) is a technique used to locate and erase unreliable data before error correction decoding. Consider a concatenated coding (CC) communication system in which the inner code employs convolutional encoding with Viterbi decoding (CEVD) and the outer code could employ either a convolutional or a Reed-Solomon code. In this study, we show that useful information can be derived from the inner Viterbi decoding process to perform two special operations: (i) to locate and erase unreliable decoded data and (ii) to estimate the input channel noise level. As a result, the number of errors input to the outer decoder is reduced and the overall CC system performance is improved. 相似文献
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LDPC编译码算法分析 总被引:1,自引:0,他引:1
低密度奇偶校验(LDPC)码是一种线性分组码,其纠错能力可以接近香农极限。针对LDPC码的编译码问题,分析了校验矩阵的构造方法。给出了LDPC码的编码算法以及算法的实现结构。分析了基于软判决的置信传播(BP)译码算法,并给出了可以进一步降低计算复杂度的简化译码方法。通过仿真对比了不同的译码算法在高斯信道下的译码性能。 相似文献
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Hybrid in-band on-channel digital audio broadcasting systems deliver digital audio signals in such a way that is backward compatible with existing analog FM transmission. We present a channel error correction and detection system that is well-suited for use with audio source coders, such as the so-called perceptual audio coder (PAC), that have error concealment/mitigation capabilities. Such error mitigation is quite beneficial for high quality audio signals. The proposed system involves an outer cyclic redundancy check (CRC) code that is concatenated with an inner convolutional code. The outer CRC code is used for error detection, providing flags to trigger the error mitigation routines of the audio decoder. The inner convolutional code consists of so-called complementary punctured-pair convolutional codes, which are specifically tailored to combat the unique adjacent channel interference characteristics of the FM band. We introduce a novel decoding method based on the so-called list Viterbi algorithm (LVA). This LVA-based decoding method, which may be viewed as a type of joint or integrated error correction and detection, exploits the concatenated structure of the channel code to provide enhanced decoding performance relative to decoding methods based on the conventional Viterbi algorithm (VA). We also present results of informal listening tests and other simulations on the Gaussian channel. These results include the preferred length of the outer CRC code for 96-kb/s audio coding and demonstrate that LVA-based decoding can significantly reduce the error flag rate relative to conventional VA-based decoding, resulting in dramatically improved decoded audio quality. Finally, we propose a number of methods for screening undetected errors in the audio domain 相似文献
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High-rate concatenated coding systems with bandwidth-efficient trellis inner codes and Reed-Solomon (RS) outer codes are investigated for application in high-speed satellite communication systems. Two concatenated coding schemes are proposed. In one the inner code is decoded with soft-decision Viterbi decoding, and the outer RS code performs error-correction-only decoding (decoding without side information). In the other the inner code is decoded with a modified Viterbi algorithm, which produces reliability information along with the decoded output. In this algorithm, path metrics are used to estimate the entire information sequence, whereas branch metrics are used to provide reliability information on the decoded sequence. This information is used to erase unreliable bits in the decoded output. An errors-and-erasures RS decoder is then used for the outer code. The two schemes have been proposed for high-speed data communication on NASA satellite channels. The rates considered are at least double those used in current NASA systems, and the results indicate that high system reliability can still be achieved 相似文献
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