共查询到20条相似文献,搜索用时 15 毫秒
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Design of Rate-Compatible Irregular Repeat Accumulate Codes 总被引:1,自引:0,他引:1
We consider the design of efficient rate-compatible (RC) irregular repeat accumulate (IRA) codes over a wide code rate range. The goal is to provide a family of RC codes to achieve high throughput in hybrid automatic repeat request (ARQ) scheme for high-speed data packet wireless systems. As a subclass of low-density parity-check codes, IRA codes have an extremely simple encoder and a low-complexity decoder while providing capacity approaching performance. We focus on a hybrid design method which employs both puncturing and extending. We propose a simple puncturing method based on minimizing the maximal recoverable step of the punctured nodes. We also propose a new extending scheme for IRA codes by introducing the degree-1 parity bits for the lower rate codes and obtaining the optimal proportions of extended nodes through density evolution analysis. The throughput performance of the designed RC-IRA codes in hybrid ARQ is evaluated for both AWGN and block fading channels. Simulation results demonstrate that our designed RC codes offer good error correction performance over a wide rate range and provide high throughput, especially in the high and low signal-to-noise ratio regions. 相似文献
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《Vehicular Technology, IEEE Transactions on》2008,57(5):2792-2803
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Ravazzi C. Fagnani F. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2009,55(11):4905-4924
In this paper, the ensembles of repeat multiple- accumulate codes (RAm), which are obtained by interconnecting a repeater with a cascade of m accumulate codes through uniform random interleavers, are analyzed. It is proved that the average spectral shapes of these code ensembles are equal to 0 below a threshold distance epsivm and, moreover, they form a nonincreasing sequence in m converging uniformly to the maximum between the average spectral shape of the linear random ensemble and 0. Consequently the sequence epsivm converges to the Gilbert-Varshamov (GV) distance. A further analysis allows to conclude that if m ges 2 the RAm are asymptotically good and that epsivm is the typical normalized minimum distance when the interleaver length goes to infinity. Combining the two results it is possible to conclude that the typical distance of the ensembles RAm converges to the Gilbert-Varshamov bound. 相似文献
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基于组合交织器的高码率RA码的设计 总被引:1,自引:1,他引:0
针对一般交织器结构的重复累积(RA)码的奇偶校验矩阵中出现的短环问题,提出将一种组合技术应用于RA码的交织器结构,设计一种新型的组合交织器,使得产生的RA码具有高码率且无4环。仿真结果显示,在码长较长和高码率的情况下,组合交织的RA码译码性能优于传统交织器。 相似文献
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一种基于分层译码和Min-max的多进制LDPC码译码算法 总被引:1,自引:0,他引:1
该文在现有译码算法的基础上提出一种高效的非二进制低密度奇偶校验码(NB-LDPC)译码方法,充分利用了分层译码算法与Min-max算法的优点,不但译码复杂度低、需要的存储空间小,而且可将译码速度提高一倍。应用该算法,对一种定义在GF(25)上的(620,509)码进行了仿真。该码的仿真结果表明:在相同误码率下,该文译码算法所需最大迭代次数仅为Zhang的算法(2011)的45%。 相似文献
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利用变量节点符号可靠度在迭代过程中的分布特征,提出了一种基于可靠度差值特征的自适应判决多元低密度奇偶校验(Low Density Parity Check,LDPC)译码算法。整个迭代过程划分为两个阶段,针对不同阶段节点可靠度的差值特征分别采用不同的判决策略:前期阶段,采用传统的基于最大可靠度的判决策略;后期阶段,根据最大、次大可靠度之间的差值特征,设计自适应的码元符号判决策略。仿真结果表明,所提算法在相当的译码复杂度前提下,能获得0.15~0.4 dB的性能增益。同时,对于列重较小的LDPC码,具有更低的译码错误平层。 相似文献
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Pfister H.D. Sason I. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2007,53(6):2088-2115
This paper introduces ensembles of systematic accumulate-repeat-accumulate (ARA) codes which asymptotically achieve capacity on the binary erasure channel (BEC) with bounded complexity, per information bit, of encoding and decoding. It also introduces symmetry properties which play a central role in the construction of new capacity-achieving ensembles for the BEC. The results here improve on the tradeoff between performance and complexity provided by previous constructions of capacity-achieving code ensembles defined on graphs. The superiority of ARA codes with moderate to large block length is exemplified by computer simulations which compare their performance with those of previously reported capacity-achieving ensembles of low-density parity-check (LDPC) and irregular repeat-accumulate (IRA) codes. ARA codes also have the advantage of being systematic. 相似文献
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本文对非规则LDPC码在RICE信道的性能进行了分析和仿真,修正了BP译码算法,证明了RICE信道满足对称性,给出了RICE信道译码稳定性条件,推导出了RICE信道的Shannon容量限,采用VC编程对码长N=49512和3072进行了仿真,同时与同码长的Turbo码进行了比较;仿真结果表明LDPC码在码长N=49512、码率R=1/3时,与Shannon限相差1dB以内、在低信噪比时其性能优于Turbo码,以及LDPC码本身有很好的交织特性和抗衰落的能力;这进一步表明了LDPC码在包括RICE信道在内的各种信道中的性能都是非常优良的. 相似文献
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本文设计了一种基于有限域GF(q)上的多元速率兼容LDPC (RC-LDPC) 码结合高阶调制的自适应编码调制(Adaptive Coded Modulation, ACM) 系统。并提出了多元RC-LDPC码在独立和相关衰落信道下的增量冗余型自适应编码调制方案。本方案中多元LDPC码码率从1/3到5/6灵活变化,以较低的系统复杂度,有效提高了系统的频带利用率。仿真结果表明:随着系统吞吐率提高,多元ACM系统相对于二元ACM系统具有越来越明显的编码增益,最高可达约9 dB。 相似文献
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A Unified Approach to the Construction of Binary and Nonbinary Quasi-Cyclic LDPC Codes Based on Finite Fields 总被引:3,自引:0,他引:3
《Communications, IEEE Transactions on》2009,57(1):84-93
A unified approach for constructing binary and nonbinary quasi-cyclic LDPC codes under a single framework is presented. Six classes of binary and nonbinary quasi-cyclic LDPC codes are constructed based on primitive elements, additive subgroups, and cyclic subgroups of finite fields. Numerical results show that the codes constructed perform well over the AWGN channel with iterative decoding. 相似文献
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重复累积码(RA)由于其编译码复杂度低、性能接近香农限的优点,目前得到学术界的广泛关注。文中研究了RA码及其译码算法,并将其应用于比特交织编码调制(BICM)系统。针对低信噪比下基于RA码的编码调制系统误码率较高的问题,提出了一种改进算法,该算法通过在解调器和译码器之间引入迭代处理,利用译码器输出的外信息改善解映射结果,从而降低了系统误码率。仿真结果表明,在加性高斯白噪声(AWGN)信道、瑞利(Rayleigh)衰落信道下,BICM系统使用迭代的译码算法与原算法相比,误码性能有较明显提高。 相似文献
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《Circuits and Systems II: Express Briefs, IEEE Transactions on》2009,56(8):629-633