Turbo码快速交织器的设计及其CPLD实现

针对目前Turbo码交织时延大影响编译码速率提升的缺陷，采用对m序列进行优选的方法设计了一种快速交织器，并基于CPLD给出硬件实现方案。仿真结果表明，该交织器在不增加编译码复杂度的情况下，一次迭代过程交织模块即能减少20％时间延迟．在时延和性能之间取得较好的折衷。     

确定性交织器的研究

本文分析了交织器在turbo码中的重要作用，以及随机交织器存在的缺陷，并提出了一种确定性交织器的设计方法。该交纪念品器具有简明的解析表达式，易于实现。计算机仿真结果表明，该确定交织器可以获得的性能优于随机交织器的平均性能。     

短帧Turbo码交织器的设计

本文给出一种分组交织器与最佳周期交织器相结合对数据进行交织的方案，可应用在短帧Turbo码交织器的设计中。通过对这种交织器的性能进行计算机模拟，本文得出在短帧Turbo码中该交织器的性能优于伪随机交织器和一般的分组交织器的性能。     

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。     

一种新的Turbo码交织器的设计

本文分析了交织器在Turbo码中的重要作用,提出了一种新交织器的设计方法,即隔行螺旋交织器.该交织器在螺旋交织器上做了简单的改进,易于实现.计算机仿真结果表明,该交织器可以获得的良好的误比特率性能.     

跳频系统中基于伪随机映射的快速交织器

为解决伪随机行列循环移位交织器在交织矩阵行数与列数不平衡时交织性能退化的问题,提出了一种基于伪随机映射的快速交织器,在伪随机循环移位之前对交织矩阵的行序进行映射置乱,从而改善交织的分散与混乱特性。数据分析与仿真结果表明,所提交织器在行列数不平衡时仍然具有较好的散乱特性,与随机交织器相当,并实现简单,支持快速交织与解交织操作, 在使用 Turbo 码的跳频通信系统受到部分时段压制干扰时,误码性能可达到随机交织器水平,优于分组交织器和互质交织器等其他常规交织器,在 40 %部分时段压制干扰下 10e-5 误码率时,较伪随机行列循环移位交织器能提升 0.6 dB 的抗干扰增益,适用于脉冲数与脉冲长度不平衡的跳频系统。     

可应用于VSAT通信系统中的差错控制方案

VSAT卫星通信系统是卫星通信领域中的一个重要应用。根据无线突发信道的特点，提出了一种交织器和前向纠错卷积码结合的差错控制方案。仿真结果表明，该方案可以提高抗误码性能，且使用m序列生成的伪随机交织器性能好于矩阵交织器。     

一种新的短帧交织器设计

分析了交织器的自交织距离与互交织距离对译码性能的影响,建立了交织距离的目标函数,提出了交织器优化设计的设计准则。在此基础上,给出了一种线性迭代的交织器设计方法,仿真结果表明该交织器具有优良的性能。     

一种周期螺栓交织器的设计

该文分析了对Turbo编码器性能影响的因素,在螺栓交织器的基础上提出了一种周期螺栓交织器,该交织器能使得可分序列变为不可分序列,增加了编码输出序列的重量。仿真结果表明,该交织器具有较优越的性能。     

基于FSM的交织器设计与实现

针对无线光通信突发信道的特点,利用有限状态机FSM控制两片RAM的读写完成了交织器的设计,解决了使用单片RAM设计交织器所带来的数据不能连续输出的问题,并对该方法下的交织器进行了时序仿真,成功验证了基于FSM的交织器的功能。     

Turbo码随机性交织器设计

深空测控中为获得较高的编码增益需要用到信道编译码技术。Turbo码是一种逼近香农限的高性能的信道编译码,其中,交织器的设计是影响Turbo码性能的关键因素之一。论述了交织器设计的基本准则,并详细介绍了3种常见的随机性交织器:伪随机交织器、S随机交织器和S改进型交织器的交织原理,对比分析了3种交织器的优缺点并给出了仿真结果。结果表明,交织器生成方式的不同将带来不同的Turbo码译码性能。     

Prunable Collision Free Random Interleaver Design

In this article we introduce a new collision free prunable random interleaver. The suggested interleaver is a joint structure involving rectangular and S-random interleaver. It comprises a general model for all kind of collision free prunable random interleavers. In addition, it can be designed for any number of parallel processors and any length of information sequence vector and can be considered also as a template for collision free prunable interleavers. The proposed interleaver can be used with all kind of turbo-like codes. The performance of the proposed interleaver is measured with parallel decodable serially concatenated convolutional codes (PDSCCCs) and compared to the PDSCCCs?? performance with collision full S-random interleaver.     

Design of cyclic shift interleavers for Turbo Codes

In this paper we consider cyclic shift interleavers for turbo coding. The properties of cyclic shift interleavers are discussed and compared with S-random interleavers. It is shown that the cyclic shift interleavers are equivalent or better than the S-random interleavers in the ability to break low weight input patterns. We estimated the performance of turbo codes with cyclic shift interleavers and compared it with the performance of S-random interleavers for varions interleaver sizes. The simulation results show that a turbo code with a cyclic shift interleaver can achieve a better performance than an S-random interleaver if the parameters of the cyclic shift interleaver are chosen properly. In addition, the cyclic interleavers have the advantages of lower design complexity and memory requirements.     

Modified Collision-Free Interleavers for High Speed Turbo Decoding

Inter-window shuffle (IWS) interleavers are a class of collision-free (CF) interleavers that have been applied to parallel turbo decoding. In this paper, we present modified IWS (M-IWS) interleavers that can further increase turbo decoding throughput only at the expense of slight performance degradation. By deriving the number of M-IWS interleavers, we demonstrate that the number is much smaller than that of IWS interleavers, whereas they both have a very simple algebraic representation. Further, it is shown by analysis that under given conditions, storage requirements of M-IWS interleavers can be reduced to only 368 storage bits for variable interleaving lengths. In order to realize parallel outputs of the on-line interleaving addresses, a low-complexity architecture design of M-IWS interleavers for parallel turbo decoding is proposed, which also supports variable interleaving lengths. Therefore, the M-IWS interleavers are very suitable for the turbo decoder in next generation communication systems with the high data rate and low latency requirements.     

Analysis and design of interleavers for CDMA systems

The turbo-principle has been applied to multiuser receivers in CDMA systems. However, the role of interleavers in these turbo-receivers has not been studied yet. In this paper, we give a notion of optimality and of mutual optimality and a way to test it. Moreover, limiting the discussion to congruential interleavers and convolutional codes, we give sufficient conditions to construct a set of mutually optimal interleavers. Also, we provide some simulations to support our results     

Performance of Möbius Interleavers for Turbo Codes

In this paper, we study the minimum free distance and error performance of turbo encoders with Möbius interleavers. In order to be capable of estimating the minimum free distance of these interleavers using binary-fixed point (BFP) algorithm, new deterministic interleavers called “truncated Möbius interleavers” are defined and constructed. It is shown how the shifted cycles of these interleavers can be related to the cycle structure of the primary Möbius transformation and its coefficients. By adjusting some parameters, an upper bound on the number of total tested BFPs for the proposed truncated Möbius interleavers is found. One distinctive property of Möbius interleavers is that their inverse can also be represented and computed with Möbius functions. Simulations are conducted to compare the error performance of the proposed truncated Möbius interleavers with quadratic permutation polynomial (QPP) interleavers whose inverses are also representable by a quadratic equation (Ryu and Takeshita in IEEE Trans Inf Theory 52(3):1254–1260, 2006). It is finally shown that the truncated Möbius interleavers can interleave sequences of information bits faster than QPP interleavers.     

Improved method for searching interleavers from a certain set using Garello’s method with applications for the LTE standard

In this paper, we propose a method for searching interleavers within a certain class, with the aim of designing turbo codes with good distance spectrum. The method is based on a modified version of Garello’s algorithm and consists in the calculation of frame error rate truncated upper bound. Here, it is applied to quadratic permutation polynomial (QPP) interleavers able to outperform those chosen for the long-term evolution (LTE) standard, for lengths up to 1,504 bits. Three classes of interleavers have been analyzed: (1) the set of QPP interleavers with the largest spread, (2) the set of QPP interleavers with a spread parameter equal to that of LTE interleaver and the highest refined nonlinearity degree, and (3) the complete set of all QPP interleavers for lengths up to 1,008. The distance spectrum optimization is made for all classes. Compared to previous methods for finding QPP-based interleavers, the search complexity is reduced, with improved performances in terms of search time, allowing interleavers of higher length. For lengths up to approximately 450, the best interleavers were found in the first class. For longer lengths, the second class contained the best ones.     

信道交错器的实现方案及其优缺点

系统地介绍信道交错器(Interleaver)技术的发展状况,包括最基本的Interleaver类型和最新发展起来的一些技术,同时对比了各种Interleaver技术的优缺点,指出Interleaver技术还存在的问题,并描述Interleaver技术的应用前景。