Weighted symbol-flipping decoding algorithm for nonbinary LDPC codes with flipping patterns

A novel low-complexity weighted symbol-flipping algorithm with flipping patterns to decode nonbinary low-density parity-check codes is proposed. The proposed decoding procedure updates the hard-decision received symbol vector iteratively in search of a valid codeword in the symbol vector space. Only one symbol is flipped in each iteration, and symbol flipping function, which is employed as the symbol flipping metric, combines the number of failed checks and the reliabilities of the received bits and calculated symbols. A scheme to avoid infinite loops and select one symbol to flip in high order Galois field search is also proposed. The design of flipping pattern＇s order and depth, which is dependent of the computational requirement and error performance, is also proposed and exemplified. Simulation results show that the algorithm achieves an appealing tradeoff between performance and computational requirement over relatively low Galois field for short to medium code length.

一类新的MDS symbol-pair码

为了对抗符号对(symbol-pair)读取信道中的符号对错误,符号对码应运而生。与经典纠错码类似,极小对距离越大,符号对码的纠错能力越强,因此,构造具有较大极小符号对距离的符号对码至关重要。根据多项式重根的判别方法,通过分析有限域F p上线性方程组的解,得到了一类最大距离可分的符号对(MDS symbol-pair)码,其长度为4 p,极小符号对距离为10。结果表明,在同样码长的情况下,新构造的MDS符号对码具有较大的极小符号对距离。

The Symbolic Significance of Holy Grail in The Da Vinci Code

Dan Brown's best-seller, The Da Vinci Code is a classical union of thriller and intelligence, and he has a good command of the knowledge on cryptology, mathematics, religion, culture and art. In addition, he organized his work fully with a large amount of information the public concerned and well-arranged them into the wonderful story.The protagonists of the book, Robert Langdon, the symbologist from Harvard and Sophie Neveu, the decode expert (The curator's granddaughter) have to solve the complicated secret by gradually investigating the strange codes and meet a series of dangerous situations. They find that what they're looking for may be a shocking secret while they solve the codes progressively during the fierce struggle with the mystery manipulator. The secret is the Holy Grail, which the Church tends to hide forever because it will destroy the faith.Therefore, this thesis will analyze the symbolic significance of Holy Grail in the book and the arguments on it against the author's viewpoint by observing related religious figures, religious phenomenon and religious organizations.

Hybrid weighted symbol-flipping decoding for nonbinary LDPC codes

A hybrid decoding algorithm is proposed for nonbinary low-density parity-check(LDPC)codes,which combines the weighted symbol-flipping(WSF)algorithm with the fast Fourier transform q-ary sum-product algorithm(FFT-QSPA).The flipped position and value are determined by the symbol flipping metric and the received bit values in the first stage WSF algorithm.If the lowcomplexity WSF algorithm is failed,the second stage FFT-QSPA is activated as a switching strategy.Simulation results show that the proposed hybrid algorithm greatly reduces the computational complexity with the performance close to that of FFT-QSPA.

Hierarchical Symbolic Analysis of Large Analog Circuits with Totally Coded Method

Symbolic analysis has many applications in the design of analog circuits. Existing approaches rely on two forms of symbolic-expression representation: expanded sum-of-product form and arbitrarily nested form. Expanded form suffers the problem that the number of product terms grows exponentially with the size of a circuit. Nested form is neither canonical nor amenable to symbolic manipulation. In this paper, we present a new approach to exact and canonical symbolic analysis by exploiting the sparsity and sharing of product terms. This algorithm, called totally coded method (TCM), consists of representing the symbolic determinant of a circuit matrix by code series and performing symbolic analysis by code manipulation. We describe an efficient code-ordering heuristic and prove that it is optimum for ladder-structured circuits. For practical analog circuits, TCM not only covers all advantages of the algorithm via determinant decision diagrams (DDD) but is more simple and efficient than DDD method.

A VERTICAL LAYERED SPACE-TIME CODE AND ITS CLOSED-FORM BLIND SYMBOL DETECTION

Vertical layered space-time codes have demonstrated the enormous potential to accommodate rapid flow data. Thus far, vertical layered space-time codes assumed that perfect estimates of current channel fading conditions are available at the receiver. However, increasing the number of transmit antennas increases the required training interval and reduces the available time in which data may be transmitted before the fading coefficients change. In this paper, a vertical layered space-time code is proposed. By applying the subspace method to the layered space-time code, the symbols can be detected without training symbols and channel estimates at the transmitter or the receiver. Monte Carlo simulations show that performance can approach that of the detection method with the knowledge of the channel.

Joint channel estimation and symbol detection for space-time block code

The simplified joint channel estimation and symbol detection based on the EM (expectation-maximization) algorithm for space-time block code (STBC) are proposed. By assuming channel to be invariant within only one STBC word and utilizing the orthogonal structure of STBC, the computational complexity and cost of this algorithm are both very low, so it is very suitable to implementation in real systems.

基于Q-Coder算术编码器的IP核设计

设计了一种实现算术编码的集成电路IP核,可用于下一代静止图像压缩标准JPEG2000编码系统中。采取易于硬件实现的二进制算术编码算法,分析了该IP核的各个模块和时序,在ModelSim软件中进行了功能仿真,在QuartusⅡ软件中完成了综合以及布局布线,并在自行设计的一块FPGA的PCI开发板上进行了验证和性能分析。实验结果表明,对相同的图像进行编码,该IP核的处理时间仅为软件处理时间的41%。该文的研究对于JPEG2000在实际中的应用有着重要的意义。

基于ARcode的移动增强现实系统研究

为解决移动设备多用户、大数据量目标的识别和跟踪问题,提出一种基于改进二维码的新型移动增强现实系统。通过C/S框架保证模型的更新,在客户端分离出识别和渲染过程,分析基于快速响应矩阵码的跟踪注册方法,针对其存在的跟踪范围小、跟踪不稳定的问题给出解决方案,从而完善系统。实验结果表明,与基于常规标志点和利用自然特征的方法相比,该系统方便实用、便于推广,且条码容易被手机使用,能识别出更多的信息。

Cooperative diversity based on rotation code

In order to obtain coding gain along with diversity gain,rotation code was applied to cooperative diversity employing decoded-and-forward cooperative protocol.Different from the same two symbols transmitted in conventional repetition-coded scheme,two different symbols were transmitted separately in two successive timeslots in the proposed rotation-coded cooperative diversity.In this way,constellation spread in the available two-dimensional signal space rather than on a single-dimensional line in repetition-coded scheme,which was supposed to be responsible for the additional coding gain.Under the proposed cooperative transmission model,upper bounds for the symbol-error-rate(SER)of cooperative diversity based on repetition code and rotation code were derived respectively.Both analytical and simulated results show that cooperative diversity based on rotation code can obtain an improved coding gain(by about 2 dB)than repetition-coded scheme without the expense of power or bandwidth.

Code Component Reuse Supporting Environment (CCRSE) and Its Design Strategy

Code Component Reuse Supporting Environment (CCRSE), which has been developed by us, is an integrated development environment. CCRSE can provide comprehensive supports for the whole process of reusing code component in the manner of dynamic composition. The architecture and functionality of CCRSE are introduced. The key achievement is giving the three strategies that are vital to successfully design CCRSE. The three strategies include: (1) according to the three pivotal technologies (encapsulation, composition and management) for supporting composition reuse of code component, design three tools respectively. (2) keep tool for supporting code component development independent of tool for supporting code component composition. (3) strictly restrict code component specification, provide the strong plug and play support for code component composition reuse, and furthest provide transparence to strictly restricted specification of code component in development of component itself.

Admissibility Conditions for Symbolic Sequences in Dynamics of Digital Filter with Two's Complement Arithmetic

In this paper, we discuss a class of piecewise linear hyperbolic maps on the 2-torus. These maps arise in the second-order digital fdter with two＇ s complement arithmetic. By introducing codings underlying the map operations, we give some admissibility conditions for symbolic sequences and find some periodic properties of these symbolic sequences. Then we use these conditions to check the admissibility of periodic symbol sequences.

A NOVEL VARIABLE-LENGTH CODE FOR ROBUST VIDEO CODING

A novel Variable-Length Code (VLC), called Alternate VLC (AVLC), is proposed in this letter, which employs two types of VLC to encode source symbols alternately. Its advantage is that it can not only stop the symbol error propagation effect, but also correct symbol insertion errors and avoid symbol deletion er-rors, so the original sequence number of symbols can be kept correctly, which is very important in video com-munication.

An Adaptive Joint Source/Channel Coding Using Error Correcting Arithmetic Codes

An approximately optimal adaptive arithmetic coding (AC) system using a forbidden symbol (FS) over noisy channels was proposed which allows one to jointly and adaptively design the source decoding and channel correcting in a single process, with superior performance compared with traditional separated techniques. The concept of adaptiveness is applied not only to the source model but also to the amount of coding redundancy. In addition, an improved branch metric computing algorithm and a faster sequential searching algorithm compared with the system proposed by Grangetto were proposed. The proposed system is tested in the case of image transmission over the AWGN channel, and compared with traditional separated system in terms of packet error rate and complexity. Both hard and soft decoding were taken into account.

基于地域文化符号的列车涂装设计研究

目的探究基于地域文化符号的列车涂装设计方法与理论。方法对列车涂装设计概念,列车涂装设计与地域文化的关联、地域文化符号的构成、罗兰·巴特文化符码理论、杨裕富设计文化符码说进行了分析和探讨;提出了列车涂装设计三层次结构模型、设计文化符码转换及应用思路;设计实验了基于地域文化符号的宁波市域列车涂装设计方案。结果验证了设计文化符码三层次模型、设计文化符码转换及应用思路对地域文化符号在列车涂装设计中的应用有效性和可行性。结论地域文化符号融入列车涂装设计中,可以体现地域文化特色,传达地域文化内涵、塑造地域文化意象;通过设计文化符码三层次结构模型能够为列车涂装设计提供分析工具和设计方法,实现列车涂装的创意定位、意义传达和设计表现。

Joint Distortion Model for Progressive Image Transmission Using Error Correcting Arithmetic Codes

A novel joint source channel distortion model was proposed, which can essentially estimate the average distortion in progressive image transmission. To improve the precision of the model, the redundancy generated by a forbidden symbol in the arithmetic codes is used to distinguish the quantization distortion and the channel distortion, all the coefficients from the first error one to the end of the sequence are set to be a value within the variance range of the coefficients instead of zero, then the error propagation coming from the entropy coding can be essentially estimated, which is disregarded in the most conventional joint source channel coding (JSCC) systems. The precision of the model in terms of average peak-signal-to-noise has been improved about 0.5 dB compared to classical works. An efficient unequal error protection system based on the model is developed, and can be used in the wireless communication systems.

Phase-domain blind estimation of symbol duration based on Haar wavelet transform

A phase-domain blind estimator of symbol duration based on Haar wavelet transform（HWT） is proposed.It can estimate the symbol duration of phase modulated signals,such as M-ary phase-shift keying（MPSK） signals and polyphase coded signals.The closed form of the spectrum of HWT is derived.Theoretical analysis shows the frequency of the first spectral peak is equal to the symbol rate,which is the reciprocal of symbol duration.Thus the symbol duration can be extracted from the spectrum.Subsequently,the optimum wavelet scale is determined according to the maximum output signal to noise ratio（OSNR） criterion.MAT-LAB simulations show that this algorithm can blindly estimate the symbol duration without any prior knowledge.This estimator need not estimate the carrier frequency and has the characteristics of low computation complexity and high accuracy.

A NEW LABELING SEARCH ALGORITHM FOR BIT-INTERLEAVED CODED MODULATION WITH ITERATIVE DECODING

Bit-Interleaved Coded Modulation with Iterative Decoding (BICM-ID) is a bandwidth ef- ficient transmission, where the bit error rate is reduced through the iterative information exchange between the inner demapper and the outer decoder. The choice of the symbol mapping is the crucial design parameter. This paper indicates that the Harmonic Mean of the Minimum Squared Euclidean (HMMSE) distance is the best criterion for the mapping design. Based on the design criterion of the HMMSE distance, a new search algorithm to find the optimized labeling maps for BICM-ID system is proposed. Numerical results and performance comparison show that the new labeling search method has a low complexity and outperforms other labeling schemes using other design criterion in BICM-ID system, therefore it is an optimized labeling method.

Totally Coded Algorithm for Switched-Current Network Analysis in Frequency Domain

Based on mirror-blocks,a totally coded algorithm(TCA) for switched-current(SI) network analysis in frequency domain is presented.The algorithm is simple,available,and suitable for any switched-current networks.A basis of analysis and design for switched-current networks via this algorithm is provided.

无尺寸约束的不透明谓词构建算法

结合不透明谓词,控制流混淆可以进行语义保持的变换,从而达到代码保护的目的。然而,现有的不透明谓词容易遭受符号执行攻击且存在小符号变量问题。为了解决上述问题,结合符号变量和数组利用单数组元素嵌套和符号变量模加运算设计不等条件表达式,并提出无尺寸约束的不透明谓词构建算法。基于该算法构建的不透明谓词混淆可以令攻击者错误地将不透明谓词识别为普通谓词或者将普通谓词识别为不透明谓词,从而有效抵御符号执行攻击。此外,利用不透明谓词检测以及虚假控制流去除等测试程序,对应用了无尺寸约束的不透明谓词混淆后程序的强度、弹性及开销进行实验测试分析。测试结果表明,基于所提算法实现的不透明谓词混淆不仅具有高强度和低开销,而且在新测试环境下仍然具有较高的抗反混淆弹性。