基于校验子的Turbo乘积码仿真研究

针对Turbo乘积码译码延时的问题,提出一种基于校验子的Turbo乘积码译码算法(S-TPC),该算法根据校验子的值采取不同方式对每行(列)进行译码,节省了一部分校验子为0的码字的硬判决译码运算量。仿真结果表明,S-TPC(32,26)在迭代4次时,能在不降低译码性能的情况下,减少近50%的计算量。     

Turbo译码原理及其在CDMA多用户检测中的应用

研究了Turbo(并行级联码)译码原理及其在CDMA多用户检测中的应用。文中简述了Turbo译码原理及逐符号最大后验算法(symbol-by-symbol MAP),并将Turbo译码原理应用于CDMA系统的多用户检测,提出了基于Turbo译码原理的多用户检测接收机方案,通过计算机仿真验证该方案的性能。结果表明,本文所提出的方案经过4次迭代之后,其误码率接近单用户界,说明这种接收机可去除多址干扰(MAI)的影响。     

软输入/软输出迭代译码算法的研究与设计

对软输入/软输出迭代译码算法进行了理论研究,分析该算法的共性,并以Turbo 乘积码的性能仿真说明迭代译码对译码性能的影响,还以理论研究为基础,对迭代译码算法进行了硬件设计,重点探讨了Turbo 乘积码的译码算法硬件设计.     

RS码软判决译码算法研究的最新进展

本文在简要介绍RS码的基本概念及其译码算法的基础上，着重介绍了近几年来RS码软判决译码算法的最新进展，其中包括最大似然译码、代数软判决译码、基于Turbo编译码的软判决译码以及基于和积算法(SPA)的软判决译码算法等。     

WCDMA中Turbo码译码算法和仿真

Turbo码是当前无线信道编码的一大进步。但由于它算法结构复杂并引起时延长,如何发挥Turbo码的强大纠错能力并使之具有实用性,这就是本文所关心的问题。本文首先解析了Turbo译码算法原理,然后结合3G标准对Turbo码的应用给出WCDMA中Max_Log_MAP的实现算法,最后运用仿真研究这种Turbo译码算法的特性。     

Turbo码软判决输出维持比译码方案的改进

Turbo码是一种新的纠错编码，具有十分强的纠错能力，Turbo码编码端采用两个或两个以上的卷积并行级联构成，译码端则采用以基于软判决信息输入/输出的反馈迭代译码结构。译码算法是Turbo码设计的核心，现巳有的两种主要的译码算法-MAP和SOVA。SOVA是一种改进的维持比算法，使其可以逐比特输出与MAP算法类似的软判决信息。该文综述了Turbo码SOVA译码的几种改进方式，并分析了这几种改进方式及仿真结果。     

Turbo码软判决输出维特比译码方案的改造

Turbo码是一种新的纠错编码，具有十分强的纠错能力。Turbo码编码端采用两个或两个以上的卷积并行级联构成，译码端则采用以基于软判决信息输入／输出的反馈迭代译码结构。译码算法是Turbo码设计的核心，现已有的两种主要的译码算法——MAP和SOVA。SOVA是一种改进的维特比算法，使其可以逐比特输出与MAP算法类似的软判决信息。该文综述了Turbo码SOVA译码的几种改进方式，并分析了这几种改进方式及仿真结果。     

Turbo码软判决输出维特比译码方案的改进

Turbo码是一种新的纠错编码,具有十分强的纠错能力。Turbo码编码端采用两个或两个以上的卷积并行级联构成,译码端则采用以基于软判决信息输入/输出的反馈迭代译码结构。译码算法是Turbo码设计的核心,现已有的两种主要的译码算法——MAP和SOVA。SOVA是一种改进的维特比算法,使其可以逐比特输出与MAP算法类似的软判决信息。该文综述了Turbo码SOVA译码的几种改进方式,并分析了这几种改进方式及仿真结果。     

Turbo乘积码译码算法的简化

Chase算法是Turbo乘积码(TPC)软判决译码中常采用的算法之一。分析了传统Chase算法中寻找竞争码字对译码复杂度的影响,在此基础上提出了两种新的简化译码算法,省去了寻找竞争码字的过程。仿真结果表明,简化算法在基本保持传统Chase算法译码性能的基础上,降低了译码复杂度,提高了译码速度。     

Turbo码译码的改进SOVA算法

Turbo编码自1993年提出以来，由于其出色的译码性能，在编码界得了广泛关注，逐渐被吸纳到一些标准化体系中，对于Turbo码的译码问题，目前已有许多种译码算法，在传统SOVA（软输出维特比算法）译码算法的基础上，给出了一种SOVA译码的改进算法，仿真结果表明该算法在译码性能等方面具有较强的优越性。     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.