Modulation and coding for information storage

Many of the types of modulation codes designed for use in storage devices using magnetic recording are discussed. The codes are intended to minimize the negative effects of intersymbol interference. The channel model is first presented. The peak detection systems used in most commercial disk drives are described, as are the run length-limited (d,k) codes they use. Recently introduced recording channel technology based on sampling detection-partial-response (or PRML) is then considered. Several examples are given to illustrate that the introduction of partial response equalization, sampling detection, and digital signal processing has set the stage for the invention and application of advanced modulation and coding techniques in future storage products     

Network coding for wireless communication networks

This special issue includes a collection of 19 outstanding research papers which cover a diversity of topics on the application of network coding in wireless communication networks.     

交通信息位置编码研究

主要介绍了对于交通数据业务中所使用的交通信息位置编码研究,该项研究提供用机器语言的方式将道路上复杂的设施及层出不穷的各类交通事件翻译后下发至数字广播终端,从而实现交通信息的实时播发的可能。     

Multiple side information streams for distributed video coding

An improved Wyner-Ziv decoder for distributed video coding (DVC) is proposed, which uses multiple side information streams obtained by using multiple reference frames. Simulation results show that the proposed algorithm can achieve a significant PSNR gain of up to 2.4 dB over the best available DVC codec at the same bit rate     

Side information aware coding strategies for sensor networks

We develop coding strategies for estimation under communication constraints in tree-structured sensor networks. The strategies have a modular and decentralized architecture. This promotes the flexibility, robustness, and scalability that wireless sensor networks need to operate in uncertain, changing, and resource-constrained environments. The strategies are based on a generalization of Wyner-Ziv source coding with decoder side information. We develop solutions for general trees, and illustrate our results in serial (pipeline) and parallel (hub-and-spoke) networks. Additionally, the strategies can be applied to other network information theory problems. They have a successive coding structure that gives an inherently less complex way to attain a number of prior results, as well as some novel results, for the Chief Executive Officer problem, multiterminal source coding, and certain classes of relay channels.     

An improved side information generation for distributed video coding

This paper presents a side information (SI) scheme for distributed video coding based on multilayer perceptron. The suggested scheme predicts a Wyner–Ziv (WZ) frame from two decoded key frames. The network is trained offline using patterns from different standard video sequences with varied motion characteristics to achieve generalization. The proposed scheme is simulated along with other standard video coding schemes. Performance comparisons have been made with respect to training convergence, rate distortion (RD), peak signal to noise ratio (PSNR), number of requests per SI frame, decoding time requirement, etc. In general, it is observed that the proposed scheme has a superior SI frame generation capability as compared to its competent schemes.     

Improved side information generation algorithm for Wyner-Ziv video coding简

Side information has a significant influence on the rate-distortion（RD） performance of distributed video coding（DVC）. In the conventional motion compensated frame interpolation scheme, all blocks adopt the same side-information generation method regardless of the motion intensity inequality at different regions. In this paper, an improved method is proposed. The image blocks are classified into two modes, fast motion and slow motion, by simply computing the discrete cosine transformation（DCT） coefficients at the encoder. On the decoder, it chooses the direct interpolation and refined motion compensated interpolation correspondingly to generate side information. Experimental results show that the proposed method, without increasing the encoder complexity, can increase the average peak signal-to-noise ratio（PSNR） by up to 1~ 2 dB compared with the existing algorithm. Meanwhile, the proposed algorithm significantly improves the subjective quality of the side information.     

A variable-length source coding theorem for correlated information sources

A variable-length source coding theorem is proved for a pair of discrete memoryless correlated information sources. The average length of codewords per source letter for source X provided the side information Y is bounded below by the conditional entropy H(X|Y) and above by the same entropy plus J/L where L is the number of source letters encoded and J is the size of ensemble Y. The Huffman encoding procedure is also generalized for this case.     

网络编码及其在光组播中的应用研究

组播应用使光网络的带宽资源日趋紧张。网络编码具有提高带宽利用率、提升网络的吞吐量、改善网络负载均衡等优点。分析了网络编码的特点及其编码代价、传统路由面临的问题,讨论了将网络编码引入光组播,优化光组播路由、提高网络吞吐量和资源利用率的研究方法。     

Noiseless coding of correlated information sources

Correlated information sequencescdots ,X_{-1},X_0,X_1, cdotsandcdots,Y_{-1},Y_0,Y_1, cdotsare generated by repeated independent drawings of a pair of discrete random variablesX, Yfrom a given bivariate distributionP_{XY} (x,y). We determine the minimum number of bits per characterR_XandR_Yneeded to encode these sequences so that they can be faithfully reproduced under a variety of assumptions regarding the encoders and decoders. The results, some of which are not at all obvious, are presented as an admissible rate regionmathcal{R}in theR_X - R_Yplane. They generalize a similar and well-known result for a single information sequence, namelyR_X geq H (X)for faithful reproduction.     

Spectral information coding by infrared photoreceptors

Spontaneous pulsing has been observed in circuits containing cryogenically cooled silicon p-i-n (p⁺-n-n⁺) diodes under dc forward bias. The intensity of infrared radiation incident on the diodes controls the pulse rate with no appreciable effect on the shape or size of the pulses. A strong similarity is noted between these properties and the nearly universal means of coding of visual information by animal photoreceptors and neural networks. It is proposed that exploitation of this remarkable analogy could lead to radically new approaches to acquisition and processing of infrared optical information. Infrared analogs of neural color coding and color vision are proposed based on analysis of p-i-n spectral response measurements.     

Wyner-Ziv视频编码中边信息生成算法研究

在Wyner-Ziv视频编码系统中,针对生成边信息容易出现块效应和重影现象的问题,提出了一种基于原始图像相关性的重叠块双向运动补偿算法.在编码端计算原始图像相关性,并将相关性数据发送到解码端辅助运动估计,得到较精确的运动矢量,最后通过重叠块双向运动补偿生成边信息.实验结果表明,与现有的双向运动补偿内插算法相比,提出的算法生成边信息的平均PSNR可以提高1.5~3dB,且边信息的主观质量也有明显改善.     

Capacity, mutual information, and coding for finite-state Markovchannels

The finite-state Markov channel (FSMC) is a discrete time-varying channel whose variation is determined by a finite-state Markov process. These channels have memory due to the Markov channel variation. We obtain the FSMC capacity as a function of the conditional channel state probability. We also show that for i.i.d. channel inputs, this conditional probability converges weakly, and the channel's mutual information is then a closed-form continuous function of the input distribution. We next consider coding for FSMCs. In general, the complexity of maximum-likelihood decoding grows exponentially with the channel memory length. Therefore, in practice, interleaving and memoryless channel codes are used. This technique results in some performance loss relative to the inherent capacity of channels with memory. We propose a maximum-likelihood decision-feedback decoder with complexity that is independent of the channel memory. We calculate the capacity and cutoff rate of our technique, and show that it preserves the capacity of certain FSMCs. We also compare the performance of the decision-feedback decoder with that of interleaving and memoryless channel coding on a fading channel with 4PSK modulation     

Channel simulation and coding with side information

Studies the minimum random bit rate required to simulate a random system (channel), where the simulator operates with a given external input. As measures of simulation accuracy the authors use both the variational distance and the d¯ distance between joint input-output distributions. They find the asymptotic number of random bits per input sample required for accurate simulation, as a function of the distribution of the input process. These results hold for arbitrary channels and input processes, including nonstationary and nonergodic processes and do not hinge on a specific simulation scheme. A by-product of the analysis is a general formula for the minimal achievable source coding rate with side information     

Efficient multi-view video coding using inter-view information

Multi-view video coding (MVC) has been extended from H.264/AVC to improve the coding efficiency of multi-view video. This paper proposes a fast mode decision algorithm which can make an early decision on the correct mode partition to solve the issue of the enormous computational complexity. The best modes of the reference views are utilized to determine the complexity of the macroblock (MB) in the current view, the mode candidates needed to be calculated can then be obtained according to the complexity. If the complexity is low or medium, the search range can be reduced. The threshold of the rate-distortion cost for the current MB is calculated using the co-located and neighboring MBs in previously coded view and is utilized as the criterion for early termination. The motion vector difference in the reference view is applied to dynamically adjust the search range in the current MB. Experimental results prove that the proposed algorithm achieves a time saving of 81.05% for a fast TZ search and 87.85% for full search, and still maintains quality performance and bitrate.     

网络环境下高校学生信息交流现状调查探究

通过文献资料法、专家访谈法、问卷调查法等研究方法对我国高校大学生在网络环境下的信息交流现状进行研究,研究认为我国大学生普遍使用一些信息交流平台与同学、老师或朋友等进行交流,同时研究结果也认为由于接触网络较久而心理厌倦及担心教师掌握行踪等是影响我国大学生信息交流的主要因素。     

“信息论与编码”课程达成度评价体系

为了持续改进课程教学质量,构建了“信息论与编码”课程达成度评价体系,主要包括教学大纲执行与授课情况分析、成绩评定与分布、课程目标达成评价和改进措施等几个部分。采用了基于“N+1”过程考核成绩进行计算的直接评价和以问卷调查形式进行统计分析的间接评价方法。在直接评价中对考核成绩进行比例划分,给出了计算公式和达成情况分布;在间接评价中对调查问卷进行了设计,并与直接评价进行了对比,最后给出了评价后的改进措施。     

Reversible information hiding for VQ indices based on locally adaptive coding

Steganography is one of protective methods for secret communications over public networks such as the Internet. This paper proposes a novel reversible information hiding method for vector quantization (VQ) compressed images based on locally adaptive coding method. The proposed steganographic method embeds a secret message into VQ indices in an index table during the process of compressing the index table in the block-by-block manner. The experimental results show that, in average, the proposed method achieves the best visual quality of reconstructed images and the best embedding rate compared to two related works. In terms of compression rate and encoding execution time, in average, Yang et al.’s method is the best, followed by our proposed method, and then Lin and Chang’s method.     

An adaptive quantization algorithm without side information for depth map coding

This paper presents a novel block-adaptive quantization scheme for efficient bit allocation without side information in depth map coding. Since the type of distortion in a depth map causes different effects in terms of the visual artifacts in a synthesized view, the proposed method adaptively assigns the number of bits according to the characteristics of the corresponding texture block. I have studied the details of the depth map and its rendered view distortion, modeled these analytically, and then proposed a new rate and distortion model for depth map coding. Finally, I derived a simple closed-form solution based on my proposed rate and distortion model, which determines the block-adaptive quantization parameter without any side information. Experimental results show that the proposed scheme can achieve coding gains of more than 0.6% and 1.4% for quarter- and full-resolution depth maps, respectively, in a multi-view-plus-depth 3D system.