共查询到19条相似文献，搜索用时 656 毫秒
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研究了Turbo码的高通信质量的信道编码问题。针对WCDMA系统中Turbo编码器采用的3GPP交织器在并行译码过程中存在内存争用问题,且串行译码存在较大时延,不能满足未来移动通信的传输时延要求,将QPP交织器应用于Turbo码编码器中,该交织器在解决内存争用及减少Turbo码译码复杂度方面具有优势,采用SF-MAX-Log-MAP并行译码算法,有效提高了码的纠错性能,更好地提高了通信过程中有效性和可靠性。 相似文献
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基于变长Turbo码的联合信源信道译码通过构造联合译码平面网格图,具有比比特级译码更好的性能.但平面网格图复杂,使变长Turbo码译码复杂度高.基于此,构造了一个空间网格图,提出基于变长Turbo码的低复杂度联合信源信道译码方法.仿真结果表明,该算法比平面网格图计算复杂度减少约3.8%,在SER(symbol error ratio)为10-4时,获得Eb/N0增益约为0.2dB. 相似文献
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Turbo码是一种新型的信道编码技术,它在无线通信中优异的纠错性能引起了众多研究人员的关注.文章设计了一种Turbo码编译码器,分析了常用的MAP译码算法,并对不同的解码算法、迭代次数以及交织长度等因素对Turbo码的性能影响进行了分析仿真,结果表明:Turbo码在无线环境中和低信躁比条件下具有优良的性能. 相似文献
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论文针对LTE下行链路中Turbo码的译码结构,提出了一种并行分块译码的方式,并针对并行分块译码中的迭代次数、分块并行度和重叠比特等关键参数进行深入分析和研究。通过研究定点小数位宽对译码性能的影响,得出Turbo码定点译码算法的合理定点方式;然后给出了一种基于非均匀量化查表的最大对数后验估计算法,并进一步简化修正项的计算。仿真结果验证了所采用的译码结构和算法的有效性。 相似文献
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本文介绍了Turbo码编码以及译码的基本原理,同时对Turbo码中的随机交织器及递归系统卷积码进行了研究。最后,用MATLAB实现了Turbo码编译码的仿真,并分析了不同参数对Turbo码性能的影响。 相似文献
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本文介绍了具有很强的抗衰落,抗干扰能力的Turbo码的编译码原理,及其在第三代移动通信系统中的性能。 相似文献
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Tubor码,由于性能接近香农理论限,在低信噪比的应用环境下比其他编码好,因而在第三代移动通信系统多种方案中,考虑将Tubor码作为无线信道的编码标准之一。论文介绍了Tubor码的结构和编解码方法,及其在移动通信系统中的应用。 相似文献
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提出了一种具有抵抗不可见位攻击的二进制指纹编码,对由基于随机序列的编码算法产生的指纹序列进行Turbo编码,之后采用扩频理论对用户指纹进行调制,使离散编码算法在对误码情况的容忍性上有了一定的提高,具有较高的合谋容忍性。 相似文献
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Tornado码二部图构造是一个非常重要的问题。基于PEG算法构造LDPC码二部图时显现的各种优点,本文提出了一种改进的PEG构图算法。仿真结果表明,改进的算法比原PEG算法有更快的执行速度,并且基于此算法构造的Tornado码也比原始的Tornado码有更好的性能。 相似文献
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One of the main challenges of coding theory is to construct linear codes with the best possible parameters. Various algebraic and combinatorial methods along with computer searches are used to construct codes with better parameters. Given the computational complexity of determining the minimum distance of a code, exhaustive searches are not feasible for all but small parameter sets. Therefore, codes with certain algebraic structures are preferred for both theoretical and practical reasons. In this work we focus on the class of constacyclic codes to first generate all constacyclic codes exhaustively over small finite fields of order up to 9 to create a database of best constacyclic codes. We will then use this database as a building block for a search algorithm for new quasi-twisted codes. Our search on constacyclic codes has revealed 16 new codes, i.e. codes with better parameters than currently best-known linear codes. Given that constacyclic codes are well known, this is a surprising result. Moreover, using the standard constructions of puncturing, shortening or extending a given code, we also derived 55 additional new codes from these constacyclic codes. Hence, we achieved improvements on 71 entries in the database of best-known codes. We use a search strategy that is comprehensive, i.e. it computes every constacyclic code for a given length and shift constant, and it avoids redundantly examining constacyclic codes that are equivalent to either cyclic codes or other constacyclic codes. 相似文献
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Iván Blanco-Chacón Dionís Remón Camilla Hollanti Montserrat Alsina 《Journal of The Franklin Institute》2014
We develop a new transmission scheme for additive white Gaussian noisy (AWGN) channels based on Fuchsian groups from rational quaternion algebras. The structure of the proposed Fuchsian codes is nonlinear and nonuniform, hence conventional decoding methods based on linearity and symmetry do not apply. Previously, only brute force decoding methods with complexity that is linear in the code size exist for general nonuniform codes. However, the properly discontinuous character of the action of the Fuchsian groups on the complex upper half-plane translates into decoding complexity that is logarithmic in the code size via a recently introduced point reduction algorithm. 相似文献
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在采用空时码的无线通信系统中,收发2端较差的路径会降低系统的性能.提出了多速率线性离散码(LDC),并对其进行了分析,给出了一种基于矩阵扩展方法的设计算法.多速率LDC是传统LDC和LDC-TAS的BER性能的折中.进而提出了一种性能优于传统LDC-A-TAS算法的多速率LDC自适应发送天线选择(A.TAS)算法. 相似文献
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数字图像处理技术是目前研究的一个热门领域,而算法的管理仍然是一个较为困难的问题。将常用的处理算法改写为统一的规范格式,通过软件进行集成管理,是解决这个问题的较好途径。对算法集成软件功能进行了设计,主要包括算法演示、多算法合成与代码添加引导,并阐述了软件的基本结构和处理流程,对该类软件的开发有很好的参考价值。 相似文献
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《Information processing & management》2022,59(3):102919
Similarity search with hashing has become one of the fundamental research topics in computer vision and multimedia. The current researches on semantic-preserving hashing mainly focus on exploring the semantic similarities between pointwise or pairwise samples in the visual space to generate discriminative hash codes. However, such learning schemes fail to explore the intrinsic latent features embedded in the high-dimensional feature space and they are difficult to capture the underlying topological structure of data, yielding low-quality hash codes for image retrieval. In this paper, we propose an ordinal-preserving latent graph hashing (OLGH) method, which derives the objective hash codes from the latent space and preserves the high-order locally topological structure of data into the learned hash codes. Specifically, we conceive a triplet constrained topology-preserving loss to uncover the ordinal-inferred local features in binary representation learning. By virtue of this, the learning system can implicitly capture the high-order similarities among samples during the feature learning process. Moreover, the well-designed latent subspace learning is built to acquire the noise-free latent features based on the sparse constrained supervised learning. As such, the latent under-explored characteristics of data are fully employed in subspace construction. Furthermore, the latent ordinal graph hashing is formulated by jointly exploiting latent space construction and ordinal graph learning. An efficient optimization algorithm is developed to solve the resulting problem to achieve the optimal solution. Extensive experiments conducted on diverse datasets show the effectiveness and superiority of the proposed method when compared to some advanced learning to hash algorithms for fast image retrieval. The source codes of this paper are available at https://github.com/DarrenZZhang/OLGH . 相似文献
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介绍了数据挖掘与决策树算法的一些基本概念,然后对最经典也得到最广泛应用的ID3算法及其改进算法作了详细介绍,在最后给出了该算法的一些数据结构和实现代码。 相似文献