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A Deterministic Construction of Irregular LDPC Codes

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Wuhan University Journal of Natural Sciences 2009年第1期14卷 39-42页

作者： ZHAN Wei zhu guangxi PENG Li Department of Electronics and Information Engineering Huazhong University of Science and Technology Wuhan 430074 Hubei China

In order to solve high encoding complexities of irregular low-density parity-check （LDPC） codes, a deterministic construction of irregular LDPC codes with low encoding complexities is proposed. The encoding algorithms are designed, whose complexities are linear equations of code length. The construction and encoding algorithms are derived from the effectively encoding characteristics of repeat-accumulate （RA） codes and masking technique. First, the new construction modifies parity-check matrices of RA codes to eliminate error floors of RA codes. Second, the new constructed parity-check matrices are based on Vandermonde matrices; this deterministic algebraic structure is easy for hardware implementation. Theoretic analysis and experimental results show that, at a bit-error rate of 10 × 10^-4, the new codes with lower encoding complexities outperform Mackay＇s random LDPC codes by 0.4-0.6 dB over an additive white Gauss noise （AWGN） channel.

关键词： low-density parity-check (LDPC) codes quasi-cyclic codes repeat-accumulate (RA) codes masking operation Vandermonde matrices

Power law and small world properties in a comparison of traffic city networks

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Chinese Science Bulletin 2011年第34期56卷 3731-3735页

作者： MA Ke WANG ZhongWen JIANG Jian zhu guangxi LI Wei Department of Physics College of Maths and Physics China University ofGeosciences Wuhan 430074 China Department of Electronics and Information Engineering Huazhong University of Science and Technology Wuhan 430074 China Department of Mathematics Kashgar Teachers College Kashgar 844006 China Institut Superieur des Materiaux du Mans 44 Avenue F.A. Bartholdi 72000 Le Mans France Institute of Particle Physics Central China Normal University Wuhan 430079 China

We analyze the statistical properties of the urban public bus networks of two cities (Beijing and Chengdu) in China. To this end, we present a comprehensive survey of the degree distribution, average path length, and clustering of both networks. It is shown that both networks exhibit small world behavior and are hierarchically organized. We also discuss the differences between the statistical properties displayed by the two networks. In addition, we propose a weight distribution approach to study the passenger flow through the public bus networks we considered. A hierarchical structure is observed here also.

关键词：城市网络小世界属性交通统计特性公交网络路径长度重量分配

TCP TRAFFIC PERFORMANCE IMPROVING IN LTE-A NETWORKS

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Journal of Electronics(China) 2013年第2期30卷 159-165页

作者： Yang Bo Wu Weimin zhu guangxi Yu Hongtao Wuhan National Laboratory of Optoelectronics National Engineering Laboratory for Next Generation Internet Access SystemDepartment of Electronics and Information EngineeringHuazhong University of Science and Technology Library Huazhong University of Science and Technology

This paper presents a novel way to improve Transmission Control Protocol (TCP) performance of the users at the edge areas of the macro cells in Long Term Evolution Advanced (LTE-A) systems. Previous works on improving wireless TCP performance are reviewed and current considerations on TCP in LTE-A are explained. However, those solutions are neither too complex nor limited to some presuppositions which are too restricting for the deployment of LTE-A networks. In this paper a substituted TCP acknowledgement transmission scheme based on Automatic Repeat reQuest (ARQ) information in layer 2 is proposed. The simulation result shows that the proposed method can reduce the delay and improve the throughput of the edging users of the cell, as well as reducing radio resources in LTE-A macro cells.

关键词： Long Term Evolution Advanced (LTE-A) Substituted Transmission Control Protocol (TCP) acknowledgement method Macro cell edging performance Automatic Repeat reQuest (ARQ) feedback

Analysis of maximal-ratio of transmitting/receiving antenna selection with perfect and partial channel information

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Frontiers of Electrical and Electronic Engineering in China 2008年第4期3卷 411-417页

作者： Xiao XIAO guangxi zhu Lin ZHOU Desheng WANG Li LI Department of Electronics and Information Engineering Huazhong University of Science and TechnologyWuhan 430074China

To improve system performance and reduce the complexity and cost of receiver hardware,we investi-gated a new multiple-input multiple-output(MIMO)scheme combining maximal-ratio transmitting and receiver antenna selection(MRT/RAS).In this scheme,a single receiving antenna,which maximizes the signal-to-noise ratio(SNR)at the receiver,is selected for *** closed-form outage probability and the bit error rate(BER)of theMRT/RAS system are both *** simulation demonstrates that the MRT/RAS scheme can achieve a full diversity order as if all the receiving antennas were *** is shown that the MRT/RAS scheme outperforms some more complex space-time codes of the same spectral *** ana-lytical results are verified by *** the end,we also analyze the MRT/RAS system based on partial chan-nel information.

关键词： multi-input multi-output(MIMO) antenna selection maximal-ratio transmitting diversity

A New Algorithm for On-Line Handwriting Signature Verification Based on Evolutionary Computation

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Wuhan University Journal of Natural Sciences 2006年第3期11卷 596-600页

作者： ZHENG Jianbin zhu guangxi Department of Electronics and Information Engineering Huazhong University of Science and Technology Wuhan 430074 Hubei China

The paper proposes an on-line signature verification algorithm, through which test sample and template signatures can be optimizedly matched, based on evolutionary computation （EC）. Firstly, the similarity of signature curve segment is defined, and shift and scale transforms are also introduced due to the randoness of on-line signature. Secondly, this paper puts forward signature verification matching algorithm after establishment of the mathematical model. Thirdly, the concrete realization of the algorithm based on EC is discussed as well. In addition, the influence of shift and scale on the matching result is fully considered in the algorithm. Finally, a computation example is given, and the matching results between the test sample curve and the template signature curve are analyzed in detail, The preliminary experiments reveal that the type of signature verification problem can be solved by EC.

关键词： on-line signature signature verification evolutionary computation

A Novel Cache Invalidation Scheme for Mobile Networks

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Wuhan University Journal of Natural Sciences 2006年第2期11卷 394-398页

作者： TAN Jin zhu guangxi LIU Jibin Department of Electronics and Information Engineering Huazhong University of Science and Technology Wuhan 430074 Hubei China

In this paper, we propose a strategy of maintaining cache consistency in wireless mobile environments, which adds a validation server （VS） into the GPRS network, utilizes the location information of mobile terminal in SGSN located at GPRS backbone, just sends invalidation information to mobile terminal which is online in accordance with the cached data, and reduces the information amount in asynchronous transmission. This strategy enables mobile terminal to access cached data with very little computing amount, little delay and arbitrary disconnection intervals, and excels the synchronous IR and asynchronous slate （AS） in the total performances.

关键词： mobile terminal cache consistency invalidation report mobile computing

A NOVEL FRAMEWORK OF ONLINE NETWORK CODING FOR MULTICAST SWITCHES WITH CONSTRAINED BUFFERS

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Journal of Electronics(China) 2011年第4期28卷 460-467页

作者： Wang Wei Yu Li zhu guangxi Li Hui Wuhan National Laboratory for Optoelectronics Division of Communiction ＆ Intelligent NetworksDepartment of Electronics and Information Engineering Huazhong University of Science and Technology Wuhan 430074 China Shenzhen Key Lab of Cloud Computing Technology ＆ Application Shenzhen Graduate School Peking University Shenzhen 518055 China

Network coding is able to address output conflicts when fanout splitting is allowed for multicast ***,it successfully achieves a larger rate region than non-coding approaches in crossbar ***,network coding requires large coding buffers and a high computational cost on encoding and *** this paper,we propose a novel Online Network Coding framework called Online NC for multicast switches,which is adaptive to constrained ***,it enjoys a much lower decoding complexity by a Vandermonde matrix based approach,as compared to conven-tional randomized network coding Our approach realizes online coding with one coding algo-rithm that synchronizes buffering and ***,we significantly reduce requirements on buffer space,while also sustaining high *** confirm the superior advantages of our contributions using empirical studies.

关键词： Packet switching Multicast Network coding Vandermonde matrix

LOW COMPLEXITY LMMSE TURBO EQUALIZATION FOR COMBINED ERROR CONTROL CODED AND LINEARLY PRECODED OFDM

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Journal of Electronics(China) 2006年第1期23卷 1-6页

作者： Qu Daiming zhu guangxi Dept of Electro. ＆ lnfo. Eng. Huazhong University of Sci. ＆ Tech. Wuhan 430074 China

The turbo equalization approach is studied for Orthogonal Frequency Division Multiplexing （OFDM） system with combined error control coding and linear precoding. While previous literatures employed linear precodcr of small size for complexity reasons, this paper proposes to use a linear precoder of size larger than or equal to the maximum length of the equivalent discrete-time channel in order to achieve full frequency diversity and reduce complexities of the error control coder/decoder. Also a low complexity Linear Minimum Mean Square Error （LMMSE） turbo equalizer is derived for the receiver. Through simulation and performance analysis, it is shown that the performance of the proposed scheme over frequency selective fading channel reaches the matched filter bound; compared with the same coded OFDM without linear precoding, the proposed scheme shows an Signal-to-Noise Ratio （SNR） improvement of at least 6dB at a bit error rate of 10 6 over a multipath channel with exponential power delay profile. Convergence behavior of the proposed scheme with turbo equalization using various type of linear precoder/transformer, various interleaver size and error control coder of various constraint length is also investigated.

关键词： Orthogonal Frequency Division Multiplexing (OFDM) Linear precoding Turbo equalization Linear Minimum Mean Square Error (LMMSE)

多用户MIMO-OFDM自适应子载波组分配的优化算法

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华中科技大学学报（自然科学版） 2007年第12期35卷 42-45页

作者：郭磊朱光喜华中科技大学电子与信息工程系湖北武汉430074

针对于多用户多输入多输出-正交频分复用(MIMO-OFDM)下行传输,提出一种基于用户信道特征反馈自适应调整多用户子载波分配的优化算法.该算法提出的简化技术将信道相关带宽信息和动态子带分配算法联合起来,将连续子载波分配的最小单元由... 详细信息

针对于多用户多输入多输出-正交频分复用(MIMO-OFDM)下行传输,提出一种基于用户信道特征反馈自适应调整多用户子载波分配的优化算法.该算法提出的简化技术将信道相关带宽信息和动态子带分配算法联合起来,将连续子载波分配的最小单元由单个子载波变为子载波组,从而能在不明显影响系统性能的基础上有效改善传统子载波自适应算法中运算量较大的问题.仿真结果表明:该算法运算量获得较大的简化,但在性能上接近于传统动态子载波分配的效果,是一种有效的多用户动态自适应子载波分配算法.

关键词：多输入多输出正交频分复用子载波分配自适应多用户