Turbo编译器中交织器的选择

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。     

Turbo码系统中交织器的设计

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。     

Turbo码中交织器和子码的综合设计

分析了距离谱和交织器结构对 Ｔｕｒｂｏ码性能的影响，介绍了高斯信道中一种新的 Ｔｕｒｂｏ码设计方法。该方法对交织器及子码进行综合设计，并给出了交织器的设计方法。仿真结果表明，通过交织器和子码的综合设计可以获得优异的误比特率性能。     

随机交织器的设计与实现

本文首先分析了随机交织器在Ｔｕｒｂｏ码中的重要作用。然后讨论了交织器长度的选择原则,并且对ＡＷＧＮ信道和Ｒａｙｌｅｉｇｎ衰落信道条件下交织深度对Ｔｕｒｂｏ码性能的影响进行了计算机模拟。在此基础上,给出了随机交织器的两种硬件电路实现方案,其中方案二便于ＡＳＩＣ实现。     

设计低资源需求的短帧Turbo码交织器

本文叙述在Ｔｕｒｂｏ码交织器中低资源需求的问题,讨论了低资源需求交织器的设计原则,分析了采用所设计交织器的距离谱和误码率特性,报告了在ＦＰＧＡ上综合布线的结果,结果表明该交织器性能较好,易于在专用集成电路上实现。     

Turbo码中快速交织器的设计

分析了交织器在Ｔｕｒｂｏ码中的重要作用，以及目前交织器存在的缺陷，介绍了一种快速交织器的设计方法。该交织器易于实现，具有交织时延低的突出优点。计算机仿真结果表明，该快速交织器可以获得优异的性能。     

基于卷积面向分组Turbo码的交织器研究

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．     

一种改进的S-random随机交织器的设计

本文对Turbo码中的关键部件——交织器作了分析，阐明了交织器在Turbo码中的重要作用。同时，混沌理论是非线性科学中的研究热点，对现代科学产生了广泛而深远的影响。本文基于Henon混沌模型和S-random交织器的设计思想提出了一种改进的交织器设计方法，并将其应用于Turbo码中。通过Turbo码的距离谱和联合界对比，本文设计的S-henon交织器在改善Turbo性能上优于S-random交织器。     

Turbo Codes的抗远近效应性能分析

一种崭新的信道编码技术Ｔｕｒｂｏ Ｃｏｄｅｓ（ＴＣ）以其优越的纠错性能很快在通信领域得到实际应用。本文讨论了这一技术在ＣＤＭＡ系统中的应用。由于采用了这种前向关错控制信道编码技术，使得ＣＤＭＡ系统具有较好的抗远近效应性能。     

Turbo Codes在INMARSAT移动卫星通信系统中的应用

本文介绍了的是ＩＮＭＡＲＳＡＴ最新推出的增强型ｍｉｎｎｉ－Ｍ系统－ＩＮＭＡＲＳＡＴ－ｐｈｏｎｅＭ４中用以实现“压缩频带的高速数据（ＨＳＤ）传输”的核心技术Ｔｕｒｂｏ Ｃｏｄｅｅｓ的具体应用方案。着重阐述Ｔｕｒｂｏ Ｃｏｄｅｓ与多电平调制结合方式,信道状态信息提取,编译码器的性能和实现上有待解决的关键问题。     

Interleaver design for turbo codes

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     

Combined turbo codes and interleaver design

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     

Recent Advances in Turbo Code Design and Theory

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.     

Permutation Polynomial Interleavers: An Algebraic-Geometric Perspective

An interleaver is a critical component for the channel coding performance of turbo codes. Algebraic constructions are important because they admit analytical designs and simple, practical hardware implementation. The spread factor of an interleaver is a common measure for turbo coding applications. Maximum-spread interleavers are interleavers whose spread factors achieve the upper bound. An infinite sequence of quadratic PPs over integer rings that generate maximum-spread interleavers is presented. New properties of PP interleavers are investigated from an algebraic-geometric perspective resulting in a new non- linearity metric for interleavers. A new interleaver metric that is a function of both the nonlinearity metric and the spread factor is proposed. It is numerically demonstrated that the spread factor has a diminishing importance with the block length. A table of good interleavers for a variety of interleaver lengths according to the new metric is listed. Extensive computer simulation results with impressive frame error rates confirm the efficacy of the new metric. Further, when tail-biting constituent codes are used, the resulting turbo codes are quasi-cyclic.     

Upper bound on the minimum distance of turbo codes

An upper bound on the minimum distance of turbo codes is derived, which depends only on the interleaver length and the component scramblers employed. The derivation of this bound considers exclusively turbo encoder input words of weight 2. The bound does not only hold for a particular interleaver but for all possible interleavers including the best. It is shown that in contrast to general linear binary codes the minimum distance of turbo codes cannot grow stronger than the square root of the block length. This implies that turbo codes are asymptotically bad. A rigorous proof for the bound is provided, which is based on a geometric approach     

Stream-oriented turbo codes

This work considers the design and performance of a stream-oriented approach to turbo codes which avoids the need for data framing. The stream paradigm applies to both serial and parallel turbo codes using continuous, free-running constituent encoders along with continuous, periodic interleavers. A stream-oriented turbo code based on parallel concatenated convolutional codes (PCCC) is considered and interleaver design criteria are developed for both block and nonblock periodic interleavers. Specifically, several nonblock interleavers, including convolutional interleavers, are considered. Interleaver design rules are verified using simulations where it is shown that nonblock interleavers with small-to-moderate delay and small synchronization ambiguity can outperform block interleavers of comparable delay. For large-delay designs, nonblock interleavers are found which perform within 0.8 dB of the capacity limit with a synchronization ambiguity of N=11     

Turbo码的优选扩散交织器设计

该文提出了Turbo码交织器的一种新的设计方法,适用于任意长度的交织设计,称为优选扩散交织,文中阐述了它的设计原则与步骤,以及对16状态Turbo码交织器的设计分析,并对其性能进行了仿真。     

Multistage recursive interleaver for turbo codes in DS-CDMA mobileradio

A multistage recursive block interleaver (MIL) is proposed for the turbo code internal interleaver. Unlike conventional block interleavers, the MIL repeats permutations of rows and columns in a recursive manner until reaching the final interleaving length. The bit error rate (BER) and frame error rate (FER) performance with turbo coding and MIL under frequency-selective Rayleigh fading are evaluated by computer simulation for direct-sequence code-division multiple-access mobile radio. The performance of rate-1/3 turbo codes with MIL is compared with pseudorandom and S-random interleavers assuming a spreading chip rate of 4.096 Mcps and an information bit rate of 32 kbps. When the interleaving length is 3068 bits, turbo coding with MIL outperforms the pseudorandom interleaver by 0.4 dB at an average BER of 10^-6 on a fading channel using the ITU-R defined Vehicular-B power-delay profile with the maximum Doppler frequency of f_D = 80 Hz. The results also show that turbo coding with MIL provides superior performance to convolutional and Reed-Solomon concatenated coding; the gain over concatenated coding is as much as 0.6 dB