基于和积算法的汉明码迭代译码性能分析

现代高效纠错码采用了迭代译码，极大地提高了系统的纠错性能，因此用迭代译码对汉明码译码系统进行了设计，并且用因子图与和积算法等现代编译码理论对汉明码的迭代译码过程进行了理论分析。实验结果表明，在加性高斯信道下，在误码率为10^-2时，汉明码迭代译码较古典译码仿真结果大概提高了3dB，同时，汉明码的迭代译码方式与最佳的枚举译码方式的性能相当，但译码复杂度有显著下降，这使得迭代译码在汉明码中的实际运用具有重要价值。     

码分多址信道中的迭代译码及干扰消除技术

提出了一种码分多址在高斯白噪声信道中的迭代译码和干扰消除方案，在译码过程中，每个用户译码器的输出用来生成用户信号的软预测，预测值通过迭代译码和干扰消除得以改进，直到迭代收敛为止，然后对用户信号进行硬判决输出，最后，给出了模拟结果。结果表明系统性能将得到改善。     

迭代检测算法在比特交织编码调制系统中的比较研究

迭代检测技术不仅局限于在传统的级联码系统中的应用,还可用于解决现代数字通信中的许多检测/译码问题.随着Turbo码的出现,人们对迭代译码算法进行深入研究,并提出一些简化译码算法.比特交织编码调制及迭代检测(bit-interleaved coded modulation with iterative decoding, BICM-ID)是一种高效数据传输系统.比特交织和迭代译码是BICM-ID系统具有卓越性能的关键因素,译码算法的选择不仅影响接收机的性能,也决定了系统的复杂度.文中研究迭代译码算法对BICM-ID系统性能的影响,分析各种译码算法的计算复杂度.仿真结果表明log-APP算法有好的性能同时复杂度也高,简化的译码算法能降低译码器的复杂度,但会带来一定的性能损失;随着信道条件的改善,算法简化带来的性能损失也随之减小.     

迭代MUD技术在SCDMA系统中的应用

介绍了同步码分多址（SCDMA）系统中的迭代多用户检测（MUD）接收机，它是Turbo译码算法迭代思想的推广，迭代多用户检测技术，用Turbo码的译码的多用户检测的研究相结合，成为目前通信领域研究的热点，研究结果表明，多次迭代后，系统性能将得到很大提高，接近单用户的性能。     

Turbo译码器低功耗设计

Turbo译码器由于其接近香农极限的优异性能而被现代通信系统所广泛使用。在实际的硬件设计中,考虑到功耗和译码延迟的存在,本文基于TD-SCDMA系统的Turbo译码器,对迭代译码性能进行了仿真,并对通过CRC校验进行找停的机制进行了仿真,对整个TD-SCDMA系统有很大的应用价值。     

基于卷积码、LDPC码、Turbo码的BICM—ID性能的研究

比特交织编码调制迭代译码（BICM—ID）是一种编码、调制和迭代译码相结合的技术,主要应用于无线通信中的信道编译码．BICM—ID在结构设计上加入了比特交织器和软输入软输出（SISO）译码器,结合迭代译码,最终实现次优译码．不同的编码方法在BICM—ID系统中也有着很大的性能差异,针对几种常见纠错编码方法——卷积码、Turbo码、LDPC码,在BICM—ID系统下的误码率性能进行比较．仿真得到系统在AWGN信道和Rayleigh衰落信道下的误码率曲线,表明不同纠错编码的BICM-ID系统性能与理论分析相一致．     

Turbo码在3G中的应用与DSP实现

Turbo码以其优越的性能逐渐在通信系统受到人们的重视，因此在概述了Turbo码的编译码算法原理以后，针对其在第三代移动通信系统（3G）中的应用，对其迭代译码进行了DSP定点仿真实现，并与Matlab浮点仿真进行了比较，在SNR为0.2dB时，误码率已近似为0，已成为3G中的首选方案。     

BICM-ID系统中的均匀重加权迭代译码算法

针对LDPC编码的BICM-ID系统,建立了正规因子图模型。从消息更新规则的角度,运用变分方法统一解释了均匀重加权置信传播算法和标准置信传播算法。将均匀重加权方法提高性能的特点与置信传播的特性相结合,推导出均匀重加权迭代译码算法,讨论了边出现概率对算法性能的影响。分别在高斯白噪声信道和不同调制方式下进行仿真实验。结果表明,提出的均匀重加权迭代译码算法性能均优于标准置信传播和差分映射置信传播等迭代译码算法。     

非顺序的 TPC 软判决迭代译码算法

针对 Turbo 乘积码(TPC: Turbo Product Code)距香农极限性能差距较大的问题, 将非顺序(NS: Non- Sequential)译码推广到软输入软输出(SISO: Soft-Input/ Soft-Output)Turbo 乘积码译码器中, 以提高误码率性能。 该算法根据决定码字的可靠度选择更可靠的行或列译码, 跳过低于可靠度门限的行或列, 以避免迭代过程中引 入额外错误而降低译码性能。 仿真结果表明, 对于以扩展汉明码(64,57,4)为子码的 TPC 码, NS-Turbo 乘积码; 迭代译码; 非顺序译码; 信道编码     

码分多址信道中的迭代译码及干扰消除技术

提出了一种码分多址在高斯白噪声信道中的迭代译码和干扰消除方案,在译码过程中,每个用户 译码器的输出用来生成用户信号的软预测,预测值通过迭代译码和干扰消除得以改进,直到迭代收敛为 止,然后对用户信号进行硬判决输出,最后,给出了模拟结果*结果表明系统性能将得到改善.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with