共查询到18条相似文献,搜索用时 345 毫秒
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本文探讨了Turbo编译码器中交织器的选择问题,首先从Turbo码的并行级联编码九基于最大后验概率(MAP)算法的迭代译码原理出发分析了交织器对Turbo码的纠错性能的巨大影响,然后总结了Turbo码中交织器设计的一些基本埋头工作春各自特点,最后给出了Turbo码中有关交织器的实用性结论。 相似文献
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Turbo码综合性能分析与Turbo编码调制 总被引:1,自引:0,他引:1
对 Turbo码的 RSC分量码、交织器、调制方式、信道以及迭代译码算法进行了综合研究与性能分析,并给出了一种基于逐比特MAP算法的Turbo编码与多元调制相结合的编码调制方式。仿真结果表明,该方案将Turbo码的高编码增益与多元调制的高频谱利用率有效地结合在一起,是一种功率和频谱高效的编码调制方式,比传统的TCM方式有更好的性能。 相似文献
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Turbo码系统中交织器的设计 总被引:7,自引:0,他引:7
Turbo码由于很好地应用了香农信道编码定理中的随机性编译码条件而获得了几乎接近香农理论发的性能。其中编、译码过程中交织器的设计是实现随机性的核心。本文主要介绍了分块交织器和伪随机交织器的设计,并提出一种两者相结合的新的交织器类型。根据仿真结果,从理论上分析了三种交织的优缺点及在不同通信领域中应用Turbo码时选取交织器的原则。 相似文献
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基于卷积面向分组Turbo码的交织器研究 总被引:2,自引:0,他引:2
交织器是影响Turbo码性能的重要因素.本文提出一种适用于基于卷积面向分组Turbo码的交织器构造方法,并由此给出一种简单实用的交织方案,模拟实验表明该交织方案性能良好. 相似文献
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改进的TurbO码算法的FPGA实现 总被引:3,自引:0,他引:3
本文提出一种使用FPGA实现改进的Turbo码算法的方法。在选用改进的最优周期交织序列的交织器和SISO(软输入软输出)译码器的Max-Log-MAP译码算法的硬件实现过程中,采用“自上而下” 和“自下而上”相结合的设计方法。在采用并行算法的同时巧妙地改变前向矢量的计算顺序,减少了占用的硬件资源。整个设计在MAX+PLUSⅡ软件环境下仿真的结果表明,本设计实现的改进的Turbo码编码/译码器具有良好的误码性能和较高的实用价值。 相似文献
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Multilevel turbo coding with short interleavers 总被引:2,自引:0,他引:2
The impact of the interleaver, embedded in the encoder for a parallel concatenated code, called the turbo code, is studied. The known turbo codes consist of long random interleavers, whose purpose is to reduce the value of the error coefficients. It is shown that an increased minimum Hamming distance can be obtained by using a structured interleaver. For low bit-error rates (BERs), we show that the performance of turbo codes with a structured interleaver is better than that obtained with a random interleaver. Another important advantage of the structured interleaver is the short length required, which yields a short decoding delay and reduced decoding complexity (in terms of memory). We also consider the use of turbo codes as component codes in multilevel codes. Powerful coding structures that consist of two component codes are suggested. Computer simulations are performed in order to evaluate the reduction in coding gain due to suboptimal iterative decoding. From the results of these simulations we deduce that the degradation in the performance (due to suboptimal decoding) is very small 相似文献
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We consider short frame turbo codes, suitable for delay-sensitive services such as conversational speech, or for encoding single ATM cells. We compare the uniform interleaver bound of Benedetto and Montorsi, and a union bound obtained by estimating the weight distribution due to the actual pseudo-random interleaver, with the simulated BER using an iterative decoder. We show that the uniform interleaver bound is significantly pessimistic at high SNR, where the random interleaver union bound is quite close. However, at lower SNR the ber exceeds the union bound, showing that it does not achieve ml decoding. We also consider half rate turbo codes formed by puncturing various proportions of the data and parity sequences, and adapt the uniform interleaver bounds for these codes. We show that while the union bounds predict better performance for data-punctured codes, in practice they perform better only at high snr and for limited proportions of data puncturing. 相似文献
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Combined turbo codes and interleaver design 总被引:1,自引:0,他引:1
The impact of the distance spectrum and interleaver structure on the bit error probability of turbo codes is considered. A new turbo code design method for Gaussian channels is presented. The proposed method combines a search for good component codes with interleaver design. The optimal distance spectrum is used as the design criterion to construct good turbo component codes at low signal-to-noise ratios (SNRs). In addition, an interleaver design method is proposed. This design improves the code performance at high SNR. Search for good component codes at low SNR is combined with a code matched interleaver design. This results in new turbo codes with a superior error performance relative to the best known codes at both low and high SNR. The performance is verified by both analysis and simulation 相似文献
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Sason I. Shamai S. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2000,46(1):24-47
The ensemble performance of parallel and serial concatenated turbo codes is considered, where the ensemble is generated by a uniform choice of the interleaver and of the component codes taken from the set of time-varying recursive systematic convolutional codes. Following the derivation of the input-output weight enumeration functions of the ensembles of random parallel and serial concatenated turbo codes, the tangential sphere upper bound is employed to provide improved upper bounds on the block and bit error probabilities of these ensembles of codes for the binary-input additive white Gaussian noise (AWGN) channel, based on coherent detection of equi-energy antipodal signals and maximum-likelihood decoding. The influence of the interleaver length and the memory length of the component codes is investigated. The improved bounding technique proposed here is compared to the conventional union bound and to a alternative bounding technique by Duman and Salehi (1998) which incorporates modified Gallager bounds. The advantage of the derived bounds is demonstrated for a variety of parallel and serial concatenated coding schemes with either fixed or random recursive systematic convolutional component codes, and it is especially pronounced in the region exceeding the cutoff rate, where the performance of turbo codes is most appealing. These upper bounds are also compared to simulation results of the iterative decoding algorithm 相似文献
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《Communications, IEEE Transactions on》2009,57(5):1215-1220
In many communications systems, data can be divided into different importance levels. For these systems, unequal error protection (UEP) techniques are used to guarantee lower BER for the more important classes. In particular, if the precise characteristics of the channel are not known, UEP can be used to recover the more important classes even in poor receiving conditions. In this paper, we derive bounds on the performance of unequal error protecting turbo codes. These bounds serve as an important tool in predicting the performance of these codes. In order to derive the bounds, we introduce the notion of UEPuniform interleaver which is a random interleaver that does not change the order of classes in the turbo code frame. We also present a method to derive the weight enumerating function for UEP turbo codes. 相似文献
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Interleaver design for turbo codes 总被引:6,自引:0,他引:6
Sadjadpour H.R. Sloane N.J.A. Salehi M. Nebe G. 《Selected Areas in Communications, IEEE Journal on》2001,19(5):831-837
The performance of a turbo code with short block length depends critically on the interleaver design. There are two major criteria in the design of an interleaver: the distance spectrum of the code and the correlation between the information input data and the soft output of each decoder corresponding to its parity bits. This paper describes a new interleaver design for turbo codes with short block length based on these two criteria. A deterministic interleaver suitable for turbo codes is also described. Simulation results compare the new interleaver design to different existing interleavers 相似文献
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Recent Advances in Turbo Code Design and Theory 总被引:1,自引:0,他引:1
Vucetic B. Yonghui Li Perez L.C. Fan Jiang 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2007,95(6):1323-1344
The discovery of turbo codes and the subsequent rediscovery of low-density parity-check (LDPC) codes represent major milestones in the field of channel coding. Recent advances in the design and theory of turbo codes and their relationship to LDPC codes are discussed. Several new interleaver designs for turbo codes are presented which illustrate the important role that the interleaver plays in these codes. The relationship between turbo codes and LDPC codes is explored via an explicit formulation of the parity-check matrix of a turbo code, and simulation results are given for sum product decoding of a turbo code. 相似文献