一种新的基-4SOVA译码算法

SOVA (Soft Output Viterbi Algorithm)类算法因其译码时延远低于MAP类算法已成为Turbo码的实用译码算法,为了进一步减小译码延迟,提高译码速度,该文在简单分析基-4Max-Log-MAP算法的基础上,提出了一种新的基-4SOVA算法,并进行了完整的数学推导.该算法的关键是提出了一种新...     

一种(5,2,3)网格码CMOS电路模拟译码器

基于后验概率算法,采用CMOS工艺,通过晶体管级的模拟电路设计,构造了完整的(5,2,3)网格码模拟概率译码器.详细分析了部分单元电路的工作原理,并给出了模拟译码器的译码性能.当信噪比大于4.8dB时,对于950KHz的输入信号,输出没有错误.当输入信号为6MHz时,误码率约为10-4,工作速度最大可达20MHz.在5V工作条件下,译码器功耗为2.957mW.模拟结果表明,在速度一定的条件下,与采用数字电路实现的译码器相比,该模拟译码器在功耗和芯片面积上至少减少了一个数量级.该文的设计方法也适用于设计Turbo码、LDPC码等的模拟概率译码器,有望在功耗和芯片面积等方面得到良好的改善.     

一种基于对称性的双向双二进制卷积Turbo码译码结构研究

该文提出了一种基于对称性的双向并行译码方案,用于提高802.16 m标准中双二进制卷积Turbo码(DB CTC)的译码速度。定义了分支度量矩阵以降低译码计算复杂度,定义了前向、后向因子矩阵,推导了前、后向度量递归计算中的对称性,并将其应用于前向、后向度量及后验概率对数似然比的双向并行计算中。构造了采用该方案的DB CTC译码器结构图,详细分析了迭代过程。以计算复杂度,存储空间,译码速度为指标考察了方案的性能,并给出了译码性能仿真曲线。分析表明,该双向并行的译码方法较常规方法提高了一倍的译码速度,而没有增加计算复杂度和存储空间。     

RS码软判决译码算法研究的最新进展

本文在简要介绍RS码的基本概念及其译码算法的基础上，着重介绍了近几年来RS码软判决译码算法的最新进展，其中包括最大似然译码、代数软判决译码、基于Turbo编译码的软判决译码以及基于和积算法(SPA)的软判决译码算法等。     

Turbo码的一种高效改进型MAP译码算法

该文给出了一种改进型最大后验概率(MAP)译码算法用于实现并行级联卷积码(Turbo码)的最优译码。与基于对数域的Log-MAP算法相比较,该文给出的算法不引入对数域,但能够完全消除标准MAP算法在迭代过程中必须进行的大量指数和对数运算。计算机仿真结果表明,这种具有最优纠错性能的改进型MAP算法能够显著减少运行时间,其译码效率甚至优于牺牲了较多纠错性能的最快速的对数域MAP译码算法(Max-Log-MAP)。     

RS码译码算法对比研究

RS码所具有的高效译码性能使其被广泛应用于数据通信和存储系统的差错控制中。本文主要对目前常用的RS码的硬判决译码算法和K—V代数软判决译码算法进行对比研究。通过对两种算法原理的理论分析,给出了RS码在硬判决与软判决的算法下的计算机仿真。结果表明两种算法均能得到良好的译码效果,而软判决译码算法较硬判决方式能更有效地带来系统增益。而软判决译码算法可以通过适当提高复杂度来改善系统的性能。     

一种基于SOVA的改进的Turbo码译码方案

本文在研究Ｔｕｒｂｏ 码反向ＳＯＶＡ（Ｓｏｆｔ－Ｏｕｔｐｕｔ ＶｉｔｅｒｂｉＡｌｇｏｒｉｔｈｍ ）译码性能的基础上,提出了一种同时利用正向和反向ＳＯＶＡ译码软输出信息的基于ＳＯＶＡ 的改进译码结构及其相应的软输出修正公式。计算机模拟结果表明,所提出的改进方案与传统的ＳＯＶＡ算法相比,其译码性能有明显的改善,并略优于Ｍａｘ－Ｌｏｇ－ＭＡＰ的性能     

分组码的一种高效软判决译码算法

本文提出了一种优先试探集软判译码算法,该算法不仅时间复杂性比经典的Chase算法有显著降低,而且译码性能也有所提高。     

MIMO系统中一种自适应的迭代检测译码算法

针对常用的非穷尽列表形式后验概率检测算法直接采用恒定且较大的列表长度,导致列表冗余度大的问题,该文提出了一种自适应长度的列表球形译码算法（Adaptive Size List Sphere Decoding,ASLSD）。在算法中通过更新检测半径和设置停止条件,使检测列表长度可随信噪比和迭代次数自适应变化。而且通过将列表操作与LSD（List Sphere Decoding）检测相结合,避免了符号序列在不同半径下的重复检测。仿真表明,在较小性能损失的前提下,该算法可以大大减小所需检测列表的长度,进而有效降低接收机的复杂度。     

MIMO系统中一种自适应的迭代检测译码算法

针对常用的非穷尽列表形式后验概率检测算法直接采用恒定且较大的列表长度,导致列表冗余度大的问题,该文提出了一种自适应长度的列表球形译码算法(Adaptive Size List Sphere Decoding, ASLSD)。在算法中通过更新检测半径和设置停止条件,使检测列表长度可随信噪比和迭代次数自适应变化。而且通过将列表操作与LSD (List Sphere Decoding)检测相结合,避免了符号序列在不同半径下的重复检测。仿真表明,在较小性能损失的前提下,该算法可以大大减小所需检测列表的长度,进而有效降低接收机的复杂度。     

Further Specialization of Clustered VLIW Processors: A MAP Decoder for Software Defined Radio

Turbo codes are extensively used in current communications standards and have a promising outlook for future generations. The advantages of software defined radio, especially dynamic reconfiguration, make it very attractive in this multi‐standard scenario. However, the complex and power consuming implementation of the maximum a posteriori (MAP) algorithm, employed by turbo decoders, sets hurdles to this goal. This work introduces an ASIP architecture for the MAP algorithm, based on a dual‐clustered VLIW processor. It displays the good performance of application specific designs along with the versatility of processors, which makes it compliant with leading edge standards. The machine deals with multi‐operand instructions in an innovative way, the fetching and assertion of data is serialized and the addressing is automatized and transparent for the programmer. The performance‐area trade‐off of the proposed architecture achieves a throughput of 8 cycles per symbol with very low power dissipation.     

一种概率自适应图像去噪模型

从小波变换入手,提出了一种概率自适应去噪模型.该模型包括尺度层间模型和层内模型.去噪方法首先利用小波域层间模型,将小波系数分成两类:有意义系数和无意义系数;然后在层内概率模型下运用最大后验概率估计方法,从有意义系数中恢复出原始系数.我们还将这种模型引入复数小波变换域.实验结果及分析表明了该去噪模型的有效性.     

Turbo Trellis Coded Modulation with Enhanced Transition Metric over Rayleigh Fading Channels

This paper investigates the performance of a new Turbo Trellis Coded Modulation scheme over correlated flat fading channels with channel interleaving. The novelty of the scheme is based on the application of a new modified transition metric incorporated in the symbol-by-symbol MAP algorithm. We consider frequency non-selective, slow Rayleigh fading channels. Extensive simulation results together with EXIT chart analysis show that the proposed scheme achieves better performance compared to the conventional transition metric when channel state information is not available at the decoder. Kostas V. Koutsouvelis was born in Thessaloniki, Greece, on July 16,1970. He received the degree Diploma in Electrical Engineering from Aristotle University of Thessaloniki, Greece in 1996 and the Master degree in Satellite Communications Engineering from University of Surrey in 1997. From 1998 to 2003 he was involved in the development of V5.2 interface as a senior software designer in Intracom plc. In 2004 joined the research and development division of Hellenic Telecommunication Organization (OTE) and his also PhD candidate at Aristotle University of Thessaloniki working with Turbo codes and Turbo Coded Modulation. Christos E. Dimakiswasborn in Serres, Greece, on July 27, 1955.He received the degree Diploma in Electrical Engineering from the Aristotle University of Thessaloniki, Greece, in 1980. Working in the satellite communications and in the error correcting coding area he received his PhD degree in digital telecommunications from the Aristotle University of Thessaloniki, Greece, in 1994. In 1980 he joined the Department of Electrical Engineering, Telecommunications Division of the Aristotle University of Thessaloniki as a research fellow. Since 1997 he is a lecturer of digital communications at the same University. Presently, his research interests include digital modulations, coding theory, satellite and mobile communications and system simulation. Stamatis S. Kouris was born in Corfu, Greece. He received the degree of Doctor Engineer in Electrical Engineering from the University of Rome, Italy and the Diploma of Specialization in Telecommunications of the Instituto Superiore, University of Rome, in 1960 and 1963 respectively. In 1971 he was awarded the PhD Degree of the University of Edinburgh, UK. In the 1974 he was awarded a specialization Diploma in administration from the University of Pomona CA, USA. He is a member of the Technical Chamber of Greece, URSI, IRI and other organizations. Since 1964 he has been involved in research on radio-propagation, antennas and microwaves, working mainly at the Fondazione Bordoni, Italy, University of Edinburgh, UK and University of Thessaloniki, Greece. He has published several papers on radio-propagation, antennas, communication transmission and microwaves and millimeter-waves devices. In 1976 he joined with the Department of Electrical Engineering, School of Engineering Science, Aristotle University of Thessaloniki. He served as professor of telecommunications from 1978 to 2002. Since 2002 he is an emeritus professor.     

Integrations of both high resolution reconstruction and non-uniformity correction of infrared image sequence based on regularized maximum a posteriori

During thermal imaging,it is vital importance to obtain high-performance images that non-uniformity noise in infrared focal plane array (IRFPA) should be eliminatined and the imaging spatial resolution...     

基于PPM调制的低密度矩阵编码与译码

 针对PPM调制信号的脉冲数具有稀疏性的特点,本文提出了一种利用低密度矩阵编码的方法,并根据最大后验概率准则进行译码.仿真结果表明,不管采用硬判决还是软判决,提出的编码方法都具有比规则LDPC码更好的纠错能力和更快的译码速度.