Memory Reliability Improvement Based on Maximized Error-Correcting Codes

Error-correcting codes (ECC) offer an efficient way to improve the reliability and yield of memory subsystems. ECC-based protection is usually provided on a memory word basis such that the number of data-bits in a codeword corresponds to the amount of information that can be transferred during a single memory access operation. Consequently, the codeword length is not the maximum allowed by a certain check-bit number since the number of data-bits is constrained by the width of the memory data interface. This work investigates the additional error correction opportunities offered by the absence of a perfect match between the numbers of data-bits and check-bits in some widespread ECCs. A method is proposed for the selection of multi-bit errors that can be additionally corrected with a minimal impact on ECC decoder latency. These methods were applied to single-bit error correction (SEC) codes and double-bit error correction (DEC) codes. Reliability improvements are evaluated for memories in which all errors affecting the same number of bits in a codeword are independent and identically distributed. It is shown that the application of the proposed methods to conventional DEC codes can improve the mean-time-to-failure (MTTF) of memories with up to 30 %. Maximized versions of the DEC codes are also proposed in which all adjacent triple-bit errors become correctable without affecting the maximum number of triple-bit errors that can be made correctable.     

级联码结合交织技术的纠错性能研究

本文将格状编码调制(TCM)技术与RS纠错码相结合,研究在数字传输系统中的纠错性能与抗干扰能力,给出了数据交织与非交织条件下差错控制系统的计算机模拟结果。模拟结果表明：采用级联码与交织技术可使信道传输的误码率从10^-3降至10^-7,编码增益提高35dB。     

On the Performance of Short Forward Error-Correcting Codes

This letter investigates the performance of short forward error-correcting (FEC) codes. Reed-Solomon (RS) codes and concatenated zigzag codes are chosen as representatives of classical algebraic codes and modern simple iteratively decodable codes, respectively. Additionally, random binary linear codes are used as a baseline reference. Our main results (demonstrated by simulations and ensemble distance spectrum analysis) are as follows: 1) Short RS codes are as good as random binary linear codes; 2) Carefully designed short low-density parity-check (LDPC) codes are almost as good as random binary linear codes; 3) Low complexity belief propagation decoders incur considerable performance loss at short coding lengths. Thus, future work could focus on developing low-complexity (near) optimal decoders for RS codes and/or LDPC codes.     

分裂认证码与纠错码

引入I-t-分裂认证码的概念。由有分裂的认证码得到纠错码,说明了当替换攻击成功的极大概率等于冒充攻击成功的极大概率时,信源数随编码规则数增大成线性增加,这一结论在无分裂认证码的情况下也成立。     

一种新型的信道纠错编码——之型码

提出了一种新型的纠错码－之型码,它可形成非常简捷的罗软输入／软输出译码规则,而且仿真结果表明,其性能在误比特率为10^-5处距香农理论极限仅0．9dB。     

利用Turbo码改善DVB-T纠错性能的仿真研究

分别介绍了Turbo码和DVB-T系统中纠错机制的基本原理,并把Turbo码技术引入到DVB-T系统的纠错机制中,利用仿真系统对改进后的纠错机制进行研究.仿真结果表明,与原系统相比,引入Turbo码的DVB-T系统能有效地改善系统的纠错性能,而且在BER=10-7时,新的纠错机制比原系统有1 dB的编码增益.     

基于AWGN信道的Turbo码性能分析

Turbo码具有近Shannon限的性能,它的出现被认为是信道编码理论发展史上的一个里程碑。文中介绍了Turbo码的发展与应用,对Turbo码的基本编译码原理进行了分析,并在AWGN信道上针对不同的交织长度和不同的分量码进行了仿真。     

衰落信道中Turbo码的应用研究

Ｔｕｒｂｏ码以其优异的性能而迅速成为近年来信道编码领域研究的热点。本文针对无线信道的特点,提出了在无线衰落信道中Ｔｕｒｂｏ码的构造方法,并基于非选择性瑞利慢衰落信道模型,分析了Ｔｕｒｂｏ码在不同信道条件下的性能。     

Error-Correcting Codes for Automatic Control

Systems with automatic feedback control may consist of several remote devices, connected only by unreliable communication channels. It is necessary in these conditions to have a method for accurate, real-time state estimation in the presence of channel noise. This problem is addressed, for the case of polynomial-growth-rate state spaces, through a new type of error-correcting code that is online and computationally efficient. This solution establishes a constructive analog, for some applications in estimation and control, of the Shannon coding theorem.      

非规则LDPC码在RICE信道中的性能分析

本文对非规则LDPC码在RICE信道的性能进行了分析和仿真,修正了BP译码算法,证明了RICE信道满足对称性,给出了RICE信道译码稳定性条件,推导出了RICE信道的Shannon容量限,采用VC编程对码长N=49512和3072进行了仿真,同时与同码长的Turbo码进行了比较;仿真结果表明LDPC码在码长N＝49512、码率R＝1/3时,与Shannon限相差1dB以内、在低信噪比时其性能优于Turbo码,以及LDPC码本身有很好的交织特性和抗衰落的能力;这进一步表明了LDPC码在包括RICE信道在内的各种信道中的性能都是非常优良的.     

新的量子纠错码的构造

量子纠错码在量子通信和量子计算中起到非常关键的作用。文中首次利用三元图上的线性码来构造新的三元量子码,并给出了具体的量子纠错码的参数。     

Intravascular Ultrasound Tissue Characterization with Sub-class Error-Correcting Output Codes

Intravascular ultrasound (IVUS) represents a powerful imaging technique to explore coronary vessels and to study their morphology and histologic properties. In this paper, we characterize different tissues based on radial frequency, texture-based, and combined features. To deal with the classification of multiple tissues, we require the use of robust multi-class learning techniques. In this sense, error-correcting output codes (ECOC) show to robustly combine binary classifiers to solve multi-class problems. In this context, we propose a strategy to model multi-class classification tasks using sub-classes information in the ECOC framework. The new strategy splits the classes into different sub-sets according to the applied base classifier. Complex IVUS data sets containing overlapping data are learnt by splitting the original set of classes into sub-classes, and embedding the binary problems in a problem-dependent ECOC design. The method automatically characterizes different tissues, showing performance improvements over the state-of-the-art ECOC techniques for different base classifiers. Furthermore, the combination of RF and texture-based features also shows improvements over the state-of-the-art approaches.     

ECOC多类分类研究综述

纠错输出编码能有效地将多类问题转化为二类问题进行求解,已受到国内外从事机器学习的研究者们的重视,并使其成为多类分类领域的研究热点.本文首先分析了ECOC多类分类的原理和框架,指出解决ECOC多类分类问题的关键在于解码策略和编码策略的确定;然后从这两个关键点出发综述了ECOC多类分类的最新进展和应用领域;最后指出了目前存在的问题以及下一步研究方向.论文研究成果将为基于ECOC多类分类方法在实际应用过程中起借鉴和参考作用.     

Product Construction of Lattices as Error-Correcting Codes

This letter investigates the so-called product lattice (PL) construction. A PL is obtained from two low-dimensional lattices by means of the Kronecker product. Fundamental properties, mainly those determining the performance of a lattice as an error-correcting scheme over a bandwidth-limited channel, are derived for PLs. Due to their special structure and properties, PLs can provide an attractive family of lattice codes of good performance/complexity tradeoffs     

纠错码数字签名方案的修正

对基于纠错码基础上构造的Xin-mei数字签名方案进行了修正,并指出在目前已知攻击方法下修正方案是安全的.     

Error-Correcting Codes Against the Worst-Case Partial-Band Jammer

This paper provides performance analyses of a broad spectrum of error-correcting codes in an antijam communication system under worst-case partial-band noise jamming conditions. These analyses demonstrate the coding advantages available for systems operating with and without frequency diversity. Utilizing both the exact approach (where possible) and upper-bounding approaches (Chernoff and union bounds), the decoded bit error rates for typical error-correcting codes (binary andM-ary, block and convolutional) have been obtained, and these codes have been compared according to theE_{b}/N_{0}required to achieve a bit error rate of 10^-5. The best performance is achieved with the use ofM-ary signaling and optimum diversity withM-ary codes, such as Reed-Solomon block codes, dual-kconvolutional codes, convolutional orthogonal codes, or concatenated codes.     

Performance Analysis of Block Codes in Hidden Markov Channels

Most investigations on the effect of channel memory on the performance of block codes use a two-state Gilbert-Elliott (GE) model to describe the channel behavior. As there are circumstances that the channel of concern can not be properly described by the GE model, there are some recent works on coded performance that characterize the channel behavior by a general finite-state Markov chain. This letter presents a new efficient systematic approach to analyze the performance of block codes in such a hidden Markov channel (HMC). An application example is given to predict codeword error probability performance of an RS-coded system in a channel with memory. Numerical results are also provided to validate our analytic results.     

Error-Correcting Codes in Projective Spaces Via Rank-Metric Codes and Ferrers Diagrams

Coding in the projective space has received recently a lot of attention due to its application in network coding. Reduced row echelon form of the linear subspaces and Ferrers diagram can play a key role for solving coding problems in the projective space. In this paper, we propose a method to design error-correcting codes in the projective space. We use a multilevel approach to design our codes. First, we select a constant-weight code. Each codeword defines a skeleton of a basis for a subspace in reduced row echelon form. This skeleton contains a Ferrers diagram on which we design a rank-metric code. Each such rank-metric code is lifted to a constant-dimension code. The union of these codes is our final constant-dimension code. In particular, the codes constructed recently by Koetter and Kschischang are a subset of our codes. The rank-metric codes used for this construction form a new class of rank-metric codes. We present a decoding algorithm to the constructed codes in the projective space. The efficiency of the decoding depends on the efficiency of the decoding for the constant-weight codes and the rank-metric codes. Finally, we use puncturing on our final constant-dimension codes to obtain large codes in the projective space which are not constant-dimension.