Turbo码中常用的交织技术

本文简要介绍了信道编码的关键技术-交织技术并给出了几种常用的交织器原理与结构。在此基础上着重介绍了适用于Turbo码的几种特殊的交织器。     

基于FPGA的Turbo码交织器的设计与实现

在Turbo码设计中,交织器的设计具有重要的地位。介绍了交织器的基本理论以及几种常见的交织器,给出了一种通用交织器的电路设计方案,并通过对两种交织器的仿真测试,验证了设计方案的正确合理。     

纠错编码系统交织器的设计

介绍了纠错编码系统中交织器的作用,以及交织器的几种类型的特性和实现方法,着重讨论了具有高度应变能力的伪随机交织器,最后对各种交织方法在不同干扰下的性能作了分析与对比,得出了一些基本结论。     

分布式视频编码中符号Turbo码交织器的设计

分析了交织器在Turbo码中的作用,指出了现有的几种交织器的缺点.设计了两种新型的基于块交织的S随机交织器和基于伪随机交织的S随机交织器.仿真结果表明,与现有的几种交织器相比,这两种交织器在Turbo码译码迭代次数及延时方面性能更好,更适合于分布式视频编码系统.     

Turbo编码中的交织技术

Turbo码是近年来提出的一种高性能的信道编码.Turbo码交织器的设计是Turbo编解码器设计中的关键.文中介绍了交织器的基本原理,详细地介绍了3种常见的交织器的交织原理.最后给出了交织器的设计准则.     

一种新型交织器的设计

在简单介绍两种常用交织器的基础上,给出了随机分组交织器的设计,并进行了计算机仿真。结果表明,此交织器设计简单,占用内存少,性能明显优于分组交织器,而仅次于随机交织器。     

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。     

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。     

交织在信道编码中的应用

在通信系统中信道编码的交织技术起着重要的作用，交织的使用提高了数据传输的可靠性。本文介绍了交织器的基本原理并对两种常用的交织器的性能进行了比较，提出了今后交织器研究的重点。     

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。     

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.     

2-Dimension Interleaver Design for IDMA Systems

A new design method interleavers, 2-dimension interleavers, are proposed for interleave division multiple access （IDMA） systems. With a same interleaving rule named I＇, the row indices and column indices of a traditional block interleaving matrix are scrambled to obtain an interleaver, which is marked as the master interleaver. F is produced by a loworder PN sequence generator. Two ways are provided for generating different interleavers. One is that all interleavers are generated by the circular shifting master interleaver. The other is that different inter leavers are generated by different Ts. Besides, we prove that the minimum distance between two adjacent bits resulted from 2-dimension interleaves is much larger than that of other schemes, such as random interleavers, power interleavers, and shiffting interleaves. The simulation results show that 2-dimension interleavers can achieve much better performance with much less resource consumption than random interleavers in IDMA systems.     

信道编码中交织技术的应用

本详细介绍了信道编码中交织技术的作用和原理。对交织器进行了分类。讨论了交织器在Turbo码中的应用,特别是讨论了交织器在改善Turbo码性能的重要作用。     

Interleaving schemes for multidimensional cluster errors

We present two-dimensional and three-dimensional interleaving techniques for correcting two- and three-dimensional bursts (or clusters) of errors, where a cluster of errors is characterized by its area or volume. Correction of multidimensional error clusters is required in holographic storage, an emerging application of considerable importance. Our main contribution is the construction of efficient two-dimensional and three-dimensional interleaving schemes. The proposed schemes are based on t-interleaved arrays of integers, defined by the property that every connected component of area or volume t consists of distinct integers. In the two-dimensional case, our constructions are optimal: they have the lowest possible interleaving degree. That is, the resulting t-interleaved arrays contain the smallest possible number of distinct integers, hence minimizing the number of codewords required in an interleaving scheme. In general, we observe that the interleaving problem can be interpreted as a graph-coloring problem, and introduce the useful special class of lattice interleavers. We employ a result of Minkowski, dating back to 1904, to establish both upper and lower bounds on the interleaving degree of lattice interleavers in three dimensions. For the case t≡0 mod 6, the upper and lower bounds coincide, and the Minkowski lattice directly yields an optimal lattice interleaver. For t≠0 mod 6, we construct efficient lattice interleavers using approximations of the Minkowski lattice     

Interleaving effects on BER fairness and PAPR in OFDMA System

Considering an Orthogonal Frequency Division Multiple Access (OFDMA) system, in this study we analyze the role of interleavers from their capability in ensuring uniformity of Bit Error Rate (BER) performance amongst the active users. In addition, we also investigate their Peak to Average Power Ratio (PAPR) properties. From the uniformity or fairness in BER perspective, we first consider a generic system and show that for a slowly changing multipath channel, individual user’s BER performance can vary from each other to a great extent, implying that the propagation channel effect is unfairly distributed on the users. Applying different types of frequency interleaving mechanisms, we demonstrate that the choice of interleaving can ensure better BER fairness on an individual user basis. In particular, by introducing the application of cyclically shifted random interleaver, we demonstrate its effectiveness in achieving BER fairness dispersion in individual users BER reduced by 89% compared to no interleaving at 15 dB Signal to Noise Ratio. We then explore the comparative performance of different interleavers considering variable number of total subcarriers, variable number of users and variable number of subcarriers per users. Finally, going back to the generic OFDMA, we investigate the PAPR distribution of different interleavers at various active user densities. Based on the results we conclude that when the total number of subcarriers per user is relatively low, i.e., a system which is heavily loaded with active users, cyclically shifted random interleavers can effectively ensure uniform performance amongst active users with reduced system complexity and manageable PAPR. In all other cases, interleaving with fixed amount of subcarrier spacing is the best solution.     

Trellis code design for periodic interleavers

A standard technique for correlated fading combines trellis codes designed for independent fading with interleaving that makes correlated fading appear to be independent for symbols within the Viterbi traceback depth. When the fading correlation is persistent and delay constraints preclude deep interleaving, some correlation remains among symbols within the traceback depth. Incorporating this post-interleaver correlation improves the trellis code design. This article presents such a trellis code design technique for periodic interleavers. Bit error rate simulations demonstrate that the new design technique can provide a dramatic performance improvement when fading or interference is severe and persistent     

Modulation and coding for the Gaussian collision channel

We study signal-space coding for coherent slow frequency-hopped communications over a Gaussian multiple-access collision channel (G-MACC). We define signal sets and interleavers having maximum collision resistance. The packet-error probability and the spectral efficiency obtained by these signal sets concatenated with outer block coding and hard (error-only) decoding is evaluated without assuming perfect interleaving. Closed-form expressions are provided and computer simulations show perfect agreement with analysis. The structure of good interleavers is also discussed. More generally, we present expressions for the information outage probability and for the achievable (ergodic) rate of the G-MACC at hand, under various assumptions on user coding and decoding strategies. The outage probability yields the limiting packet-error probability with finite interleaving depth (delay-limited systems). The achievable rate yields the limiting system spectral efficiency for large interleaving depth (delay-unconstrained systems). Comparisons with other classical multiple-access schemes are provided     

Design of interleavers for turbo codes: iterative interleavergrowth algorithms of polynomial complexity

This paper addresses the problem of designing interleavers for parallel concatenated convolutional codes (PCCCs) tailored to specific constituent codes. We start by establishing the role of the interleaver in the PCCC and the various parameters that influence the performance of the PCCC with a given interleaver. Subsequently, we define a canonical form of the interleaving engine denoted as the finite-state permuter (FSP) and demonstrate the minimal delay property of this canonical form. For any given permutation, we present a procedure for deriving the canonical FSP engine. We address the issue of implementation of the FSP and propose a very simple structure for the FSP. Next, using the structural property of the FSP engine, we develop a systematic iterative technique for construction of interleavers with a complexity that is polynomial in the interleaver size. Subsequently, we develop a cost function that, coupled with the iterative interleaver growth procedure, can be used to design optimized interleavers for PCCCs. We provide examples of application of the interleaver design technique, and compare the designed interleavers with some of the interleavers of comparable size found in the literature