共查询到17条相似文献,搜索用时 93 毫秒
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针对规则LDPC码,采用了行列都均匀的(evenboth)随机构造H的方式,在瑞利平坦衰落信道下和卷积码的性能进行了对比,证明了规则LDPC码在中短帧传输下在瑞利平坦衰落信道的优异性能。这对LDPC码应用于实际无线通信系统具有重要参考价值。 相似文献
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近年来,结构化低密度奇偶校验(LDPC)码的构造方法受到了广泛地关注.本文提出了一种利用最大距离分割(MDS)编码构造结构化LDPC码的思路.该思路将基于两个信息符号的RS码构造LDPC码的方法扩展至适用于所有的MDS码.本文以具有MDS特性的卷积码为例详细描述该构造方法的细节,并构造了码长从255比特到4095比特的高码率LDPC码.由于卷积码的MDS定义不同于线性分组码,因此本文给出了一种对卷积码截短的方法及其必要的证明.仿真结果表明,本文构造MDS-Conv-LDPC码的性能优于随机构造的LDPC码. 相似文献
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为降低数字通信系统传输差错并提高可靠性,从工程应用角度出发,在DSP硬件平台上实现(2,1,7)卷积码。用MATLAB仿真影响(2,1,7)卷积码性能的各个参数,与约束度为3和码率为3/4、2/3的卷积码进行对比,其仿真结果为DSP硬件实现奠定理论基础。最后选用TI公司的TMS320DM6437型号,在CCS3.3开发环境上运行。实验表明:约束度为7、码率为1/2的卷积码在较低的信噪比(SNR=6 dB)下误码率则可达到10-6,且DSP实现的(2,1,7)卷积码方便可行,快速稳定,译码准确,并具有较强的纠错能力。 相似文献
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π旋转LDPC码克服了以往LDPC码编码复杂度高的缺点,具有码率变化灵活,长码构造简单,无需求出生成矩阵,节约储存空间等优点。为了提高超宽带(UWB)系统的传输可靠性,利用π旋转LDPC码设计了一种不采用交织的多带正交频分复用(MB-OFDM)超宽带的实现方案,并通过仿真计算分析了π旋转LDPC码与并行级联卷积码的性能差异。 相似文献
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截断式原模图低密度奇偶校验(LDPC)卷积码(P-LDPC-CCs)结合了原模图LDPC (P-LDPC)码和卷积码的特点,具有多变的编码构造方式和优异的纠错性能,实现了编译码低时延特性。边扩展作为构造截断式原模图LDPC卷积码基础矩阵关键步骤,是影响其性能的重要因素。该文提出了一种边扩展优化方法。该方法利用原模图外信息转移(P-EXIT)算法理论分析基础矩阵的译码门限,引入差分进化思想搜索一定条件下最优的边扩展方式。理论分析与系统仿真结果均表明所提边扩展优化方法比现有的方法具有更好的性能。 相似文献
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Pusane A.E. Feltstrom A.J. Sridharan A. Lentmaier M. Zigangirov K. Costello D.J. 《Communications, IEEE Transactions on》2008,56(7):1060-1069
Potentially large storage requirements and long initial decoding delays are two practical issues related to the decoding of low-density parity-check (LDPC) convolutional codes using a continuous pipeline decoder architecture. In this paper, we propose several reduced complexity decoding strategies to lessen the storage requirements and the initial decoding delay without significant loss in performance. We also provide bit error rate comparisons of LDPC block and LDPC convolutional codes under equal processor (hardware) complexity and equal decoding delay assumptions. A partial syndrome encoder realization for LDPC convolutional codes is also proposed and analyzed. We construct terminated LDPC convolutional codes that are suitable for block transmission over a wide range of frame lengths. Simulation results show that, for terminated LDPC convolutional codes of sufficiently large memory, performance can be improved by increasing the density of the syndrome former matrix. 相似文献
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LDPC block and convolutional codes based on circulant matrices 总被引:18,自引:0,他引:18
Tanner R.M. Sridhara D. Sridharan A. Fuja T.E. Costello D.J. Jr. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2004,50(12):2966-2984
A class of algebraically structured quasi-cyclic (QC) low-density parity-check (LDPC) codes and their convolutional counterparts is presented. The QC codes are described by sparse parity-check matrices comprised of blocks of circulant matrices. The sparse parity-check representation allows for practical graph-based iterative message-passing decoding. Based on the algebraic structure, bounds on the girth and minimum distance of the codes are found, and several possible encoding techniques are described. The performance of the QC LDPC block codes compares favorably with that of randomly constructed LDPC codes for short to moderate block lengths. The performance of the LDPC convolutional codes is superior to that of the QC codes on which they are based; this performance is the limiting performance obtained by increasing the circulant size of the base QC code. Finally, a continuous decoding procedure for the LDPC convolutional codes is described. 相似文献
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Johannes Pittermann Michael Lentmaier Kamil Sh. Zigangirov 《AEUE-International Journal of Electronics and Communications》2005,59(4):254-257
A new construction combining LDPC convolutional codes and multilevel coding/modulation is suggested and analyzed. In the case of QPSK, we demonstrate that it has a better performance than an LDPC convolutional code combined with conventional Gray mapping. 相似文献
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A class of serial concatenated ordinary (non-punctured) convolutional (SCOC) codes is introduced. Simulation results over additive white Guassian noise channels show that the SCOC codes have comparable performance as 3GPP turbo codes and LDPC codes, while with overall decoding complexity smaller than that of LDPC codes and 3GPP turbo codes. 相似文献