单载波频域均衡技术的研究

介绍了单载波频域均衡技术的原理,在理论上对SC-FDE系统和OFDM系统的峰值平均功率比及对载波频偏和相位噪声的敏感度进行了比较.最后对SC-FDE系统和OFDM系统的性能进行了计算机仿真.     

单载波频域均衡在地空高速数据链的应用

地空数据链的信道属于低仰角的多径信道,存在较严重的符号间干扰。正交频分复用(OFDM)是得到认可的有效抗多径方案,单载波频域均衡(SC-FDE)采用与OFDM相似的频域均衡方式,具有与OFDM相近的性能和复杂度,并克服了OFDM的一些不足。在比较SC-FDE和OFDM相似性、分析SC-FDE的信道估计与均衡基础上,提出了采用SC-FDE的地空高速数据链解调器结构,该结构在保留单载波处理的优点条件下实现高效的频域均衡。     

MIMO单载波分数阶傅里叶域均衡系统及最优阶次选择方法

单载波频域均衡（SC-FDE）技术可以有效地克服无线传输中的多径衰落,而多输入多输出（MIMO）能大大提高频谱利用率。两者的结合已成为下一代无线通信系统上行链路的传输方案。然而,当无线信道是快速时变时, MIMO SC-FDE系统的频域信道矩阵将为非对角矩阵,形成严重的频域子信道间干扰,使系统性能急剧下降。针对这一问题,本文采用在分数阶傅里叶域均衡代替传统频域均衡,提出MIMO单载波分数阶傅里叶域均衡（MIMO SC-FrFDE ）系统。通过选择合适的分数阶傅里叶变换阶次,实现分数阶傅里叶域信道矩阵的近似对角化。仿真结果表明,在快速时变信道下,本文提出的MIMO SC-FrFDE系统比传统MIMO SC-FDE具有更好的误码率性能。     

单载波频域均衡消除符号间干扰的研究

介绍了单载波频域均衡（SC-FDE）系统以及SC-FDE所常用的频域块最小均方（FBLMS）算法。为了进一步改进单载波频域均衡系统的性能，基于抽头泄漏的思想，通过增加抽头的泄漏进一步优化了FBLMS算法，并对基于优化算法的单载波频域均衡系统进行了计算机仿真模拟。其仿真结果表明：与常用算法相比较，该优化算法能有效提高均衡器的收敛速度和显著改善均衡器消除符号间干扰（ISI）的性能。     

SC-FDE系统中归一化FBLMS算法的研究

单载波频域均衡（SC-FDE）系统传统上采用最小均方误差（MMSE）算法和快速块最小均方（FBLMS）算法进行频域均衡,文中对单载波频域均衡系统中归一化FBLMS算法进行了仿真研究,并与MMSE算法和FBLMS算法进行比较。测试和分析了系统的均方误差和误码率。仿真结果表明：该算法克服了收敛速度和失调量之间的矛盾,提高了算法的收敛速度,降低了误码率,该结果对SC-FDE系统的进一步研究具有参考价值。     

一种无循环前缀迭代单载波频域均衡算法

单载波频域均衡（SC—FDE）技术可以有效消除符号间干扰（ISI）,相对于正交频分复用（OFDM）,具有较低的峰均比,因此成为宽带无线通信关键技术之一。传统的SC-FDE系统需要在发送帧前加入循环前缀（CP）,且CP长度要大于信道最大多径时延,这就降低了频带利用率,使得发射机功率增加。本文在取消CP情况下,提出一种辅助补零算法,恢复发送信号和信道的循环卷积,并通过迭代处理消除干扰。仿真结果表明,在信噪比大于3dB后,所提算法误码率更接近相同信噪比条件下的高斯白噪声信道,性能也较为理想。     

一种针对双衰落信道OFDM的新均衡算法

在OFDM系统中，子载波间的正交性是保证OFDM性能的重要保障。针对双选择性衰落信道下的OFDM系统，该文在分析载波间干扰（ICI）的基础上，提出了一种采用频域迭代消除ICI的均衡算法。分析和仿真结果表明此方法能有效地保证载波间的正交性和改善了OFDM系统的误码率（BER）性能。     

单载波频域均衡与多载波OFDM误码性能的理论比较

单载波频域均衡(SC-FDE)和多载波正交频分复用(OFDM)是数字通信中用于克服多径衰落的两种技术。本文通过理论推导对这两种技术在高斯白噪声通信信道巾的误码性能进行了比较。利用高斯分布尾部概率的数值变化特性,本文推导出如下结论:在低信噪比条件下,OFDM的误码性能略优于SC-FDE,而在高信噪比条件下,SC-FDE则能取得显著优于OFDM的误码性能。这一结论对于通信系统的设计具有重要的参考价值。     

短波FH/OFDM通信系统抗跟踪式干扰性能分析

对于短波多载波跳频通信系统,跟踪式干扰是一种有效的干扰模式。分析了正交频分复用( OFDM)部分子信道干扰与符号误码率的关系,通过仿真获得了最佳跟踪干扰的部分时间参数,结合OFDM频谱结构与干扰频谱关系,推导了高斯信道条件下部分频带干扰和多音干扰时系统误码率,分析了短波FH/OFDM通信系统抗跟踪式干扰的误码率性能,仿真结果表明：跟踪干扰时间窗口对误码率的影响与部分频带干扰因子和信干比有关;在部分频带干扰与部分时间干扰之间,存在等效的干扰效果区域;多音干扰因子越大,系统所受影响越大,跟踪干扰时间窗口对误码率的影响与多音干扰因子和信干比有关,针对OFDM符号的多音干扰影响要远大于部分频带干扰的影响;跳频与OFDM技术的结合、提高载波跳速、减小跟踪式干扰对OFDM符号的影响,也是消除多音干扰的重要手段。     

水声通信系统中基于迭代自适应的脉冲噪声抑制方法

针对水声通信系统中脉冲噪声抑制问题,提出了一种迭代自适应的脉冲噪声抑制方法。基于 OFDM子载波之间的正交性,该方法首先利用空子载波矩阵从接收信号中提取出背景噪声和脉冲噪声。然后,利用空子载波矩阵构造导频矩阵,得到脉冲噪声的干扰协方差矩阵,并在加权最小二乘准则下通过对代价函数的求解得到脉冲噪声的闭式解。最后,在接收信号中减去脉冲噪声的估计值,完成对脉冲噪声的抑制。仿真结果表明,本文方法有效降低了水声通信系统的误码率,且在高信干噪比下性能提升更加明显。     

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.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

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.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

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.     

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.