基于FPGA的改进Turbo译码器的设计与实现

Turbo码的译码性能几乎接近shannon理论极限,实现Turbo译码器对于降低信道传输的误码率、提高传输可靠性具有重要的意义。本文设计了一种基于SOVA算法的改进Turbo译码器,并下载到Xilinx公司的Spartan-3S1500 FP-GA开发板上验证成功。Turbo译码器的输入信息和输出信息通过FPGA板与PC机的通信获得。实验结果表明,所设计的Turbo译码器是正确的。     

使用SIMULINK构建Turbo码仿真系统

本文在介绍了Turbo码的码编译码原理之后,详细介绍了如何基于SIMULINK构建一个完整Turbo码编译码以及在信道中传输的仿真系统,并且通过仿真分析了Turbo码交织器大小、传输信道、译码算法等因素对Turbo码性能的影响。     

基于Turbo码的CBTC系统安全信息传输研究

针对城市轨道交通的无线列车控制系统(CBTC)中基于无线信道的信息安全传输问题,提出了基于Turbo码的CBTC无线信道的安全信息传输控制方案,并分别采用Bi-SOVA译码算法、SOVA译码算法、MAP译码算法及对数域Max-Log-MAP译码算法等进行了仿真测试与比较分析.仿真结果表明,所提出的基于Turbo码的传输控制方案能够有效地满足CBTC安全信息传输的误码率要求,并且在所采用的译码算法中,Bi-SOVA算法和Max-Log-MAP算法具有较好的误码率性能.因此,在无线列车控制系统的信息传输中用Turbo码来代替传统的CRC码进行差错控制是合理而有效的.     

基于深度学习的Turbo码译码研究

译码器通常被设计用于高斯信道,对于非高斯信道而言却是次优的。深度学习方法为设计译码器提供了一种新的方法,可以对任意信道的数据进行训练和学习。为了克服传统模式存在的弊端,提出了一种新的基于卷积神经网络(CNN)的Turbo码译码方案。通过搭建神经译码网络模型,采用交叉熵函数(BCE)作为损失函数,对生成的编码数据进行网络训练,使得训练网络能够更好地提取特征关系,从而拟合出Turbo码的最佳译码函数。试验结果表明:基于卷积神经译码网络在加性高斯白噪声(AWGN)信道上和标准的Turbo解码器性能接近,但在非AWGN信道上却表现出相比于标准译码器更好的适应性和鲁棒性,适用于任意信道。此外,卷积神经译码网络还可以用于低密度奇偶校验(LDPC)码和Polar码的译码,有利于提出更多端到端训练有素的神经译码器。     

基于FPGA的DSC高速译码器设计及实现

采用易于FPGA实现的归一化最小和算法,通过选取合适的归一化因子,将乘法转化成移位和加法运算。在高斯白噪声信道下,仿真该译码算法得出最佳的译码迭代次数,并结合Xilinx XC7VX485T资源确定量化位数。然后基于该算法和这3个参数设计了一种全新的、高速部分并行的DSC译码器。该译码器最大限度地实现了译码效率、译码复杂度、FPGA资源利用率之间的平衡,并在Xilinx XC7VX485T芯片上实现了该译码器,其吞吐率可达197 Mb/s。     

带限信道的Turbo均衡、信道估计和TTCM

给出了适用于带宽有限信道的Turbo均衡和译码模型,该模型基于高带宽效率的TTCM译码、软输入软输出均衡器和软输入WRLS信道估计。该模型的均衡器和译码器使用LOG-MAP准则,通过均衡器和译码器间的迭代可以获得更高的增益。     

一种适合于并行译码的Turbo交织器的设计

高数据率的通信系统要求有高吞吐量的译码器,而并行译码是高吞吐量的译码器的一种有效实现方法。对于采用并行译码的Turbo码,交织器的设计是决定其性能和译码器吞吐量的关键因素。本文在A.Giuliett提出的没有读写冲突的并行交织器的设计原则基础上,给出了一种新型的交织器设计方法。该方法在保证Turbo优越性能的前提下,使得高并行度的译码成为可能。译码性能的仿真结果验证了设计方案的良好译码性能,通过FPGA的硬件实现验证了译码器吞吐量的极大提高。该设计方案可用于Beyond3G系统。     

应用于LTE-OFDM系统的Viterbi译码在FPGA中的实现

在OFDM系统中,为了获得正确无误的数据传输,要采用差错控制编码技术。LTE中采用Viterbi和Turbo加速器来实现前向纠错。提出一种在FPGA中实现的基于软判决的Viterbi译码算法,并以一个(2,1,2)、回溯深度为10的软判决Viterbi译码算法为例验证该算法,在Xilinx的XC3S500E芯片上实现了该译码器,最后对其性能做了分析。     

高效LDPC译码器的优化与FPGA实现

针对高效LDPC译码器设计过程中的参数选择问题,提出了针对Turbo译码消息传播（Turbo decoding message passing,TDMP）译码算法的离散密度进化算法。利用这种离散密度进化算法对译码算法中的校正因子及量化精度进行了优化。与传统的通过数值仿真进行优化的方法相比,本文算法效率大大提高,且效果显著。测试结果表明,优化的定点化译码器与纯浮点仿真相比性能只相差0.1 dB左右。在译码器实现结构设计中提出了一种基于分布式RAM的P消息循环存储结构,与传统的基于寄存器和Benes网络的存储器结构相比,资源消耗明显下降。在Xilinx公司的FPGA平台上进行了硬件实现与测试,结果表明与同类译码器相比在资源消耗和吞吐率上均有一定优势,是一种高效的LDPC硬件译码器。     

无线局域网中Turbo码的应用研究

通过分析无线局域网中敖据传输的特点,对Turbo码鳊码和译码方案进行适合于WLAN的改进,设计出无线局域网中Turbo码编译码器的实现方案.通过计算机仿真研究相关参数的变化对Turbo码性能的影响.并与传统WLAN中应用广泛的卷积码进行性能比较,仿真结果表明,利用Turbo码编码技术能够较大地提高无线局域网传输性能.     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。