一种OFDM中继系统的有限反馈预编码方法

基于正交频分复用的放大转发协作中继系统,为了减少系统误比特率、增加信道容量和增强实用性,该文提出一种实用的源节点预编码和中继节点预编码的联合优化有限比特反馈的预编码方法。利用3节点构成的两个下行链路,实现两跳协作通信方式;采用SVD分解和QR(orthogonal triangular)分解相结合设计预编码,其中源节点预编码每帧只要一个;优选量化码本,把预编码矩阵量化后反馈到发射端。仿真结果表明,该方案能提高平均和速率、降低误码率和改善中断概率特性,且反馈比特数较少具有更好的实用价值。     

动态频谱抗干扰系统在部分频带干扰下的性能

为了评估动态频谱抗干扰新体制在抗干扰通信中的性能,采用理论分析与仿真相结合的方法,研究了动态频谱抗干扰系统在部分频带干扰下的信道容量及比特误码率,并将其与常规跳频系统在部分频带干扰下的信道容量及比特误码率进行了比较.结果表明:在很宽的部分频带干扰因子取值范围内,动态频谱抗干扰系统的信道容量均大于常规跳频系统的信道容量,...     

FH/BFSK系统的常见干扰策略分析

抗干扰能力的研究始终是跳频通信系统中的关键问题。为了有效衡量常见干扰策略对于FH/BFSK系统的影响,首先指出干扰跳频系统的基本思路和评估标准。以不同的干扰策略为标准,划分常见的干扰类型。分别论证其基本原理、干扰效果和应用环境。基于FH/BFSK系统,计算不同类型干扰策略下的比特误码率。搭建系统的Matlab/Simulink模型,得到典型干扰的参数对误比特率的影响结果。为跳频通信的抗干扰研究提供了评估依据和仿真参考。     

对跳频通信的阻塞式干扰

对地面战术级甚高频跳频通信实施干扰,当前较有效的方式是阻塞式干扰。在野战条件下宜采用升高干扰和分布干扰。采用锯齿波宽带调频和杂音窄带调频混合模式的阻塞式干扰体制可对跳频通信实施最佳干扰。而实施分段宽带干扰,可有效干扰敌跳频通信,并可保证我方正常通信。     

跳频通信系统抗宽带噪声干扰性能研究

跳频通信系统作为扩频通信系统的一种,具有较强的抗干扰性能,已经被广泛地应用于军事通信和民用移动通信系统中。在实际的跳频通信系统工作环境中,经常会受到宽带噪声的干扰。文章主要介绍了跳频通信系统的组成及主要技术指标,研究了在宽带噪声干扰环境下跳频通信系统的抗干扰性能,得出了在不同强度的宽带噪声干扰下通信误码率,给出了跳频通信系统抗干扰的改进方法,为提高跳频通信系统的抗干扰性能提供了参考性的建议。     

存在检测误差的抗跟踪干扰最优跳速设计

跟踪干扰对跳频通信构成严重威胁。首先采用Stackelberg博弈模型对存在检测误差条件下的通信干扰与抗干扰进行建模,在该模型中,存在一个先行者和一个跟随者,其中,通信方作为先行者进行跳频通信,跟踪干扰方作为跟随者检测跳频通信信号并实施干扰。分别推导了通信方的最优跳速,以及干扰方最优检测时间与干扰时间的分配策略,证明了当信噪比小于一定门限时,干扰方的最优干扰策略是盲干扰,通信方的最优抗干扰策略是慢速跳频。最后,对理论分析结果进行了计算机仿真验证,并将所提算法与盲跳频和变速跳频进行了比较,结果表明,所提算法的抗跟踪干扰性能显著优于已有算法。      

一种前向放大中继通信系统中的有限反馈中继预编码方案

 本文首先给出了前向放大中继通信系统中,在给定QoS要求下的最优中继预编码矩阵的设计. 进而,针对实际通信系统中反馈信道带宽的限制,给出了一种有限反馈中继预编码码本的设计方案. 计算机仿真表明,本文所提新码本有限反馈中继预编码方案的系统性能随着反馈比特数的增加接近完全反馈下的系统性能,且在相同反馈比特数下的系统容量和误码率均明显优于将传统MIMO通信系统中的Grassmannian码本或随机码本直接应用于中继预编码的有限反馈方案.     

跳频通信技术研究及仿真分析

跳频通信系统具有较强的抗干扰能力,在现代通信中具有广泛的应用.了解跳频通信基本原理及不同干扰样式下抗干扰性能,能在通信对抗中实施更有效的干扰与反干扰.在对跳频通信基本原理进行分析阐述的基础上,采用Matlab/Simulink对跳频通信系统进行了仿真.针对宽度噪声干扰、 部分频带干扰和单音干扰3种特定干扰样式下跳频通信...     

基于Simulink的高速跳频通信系统抗干扰性能分析

随着通信技术的发展,跳频技术特别是高速跳频技术已经成为军事通信抗干扰的重要方式。介绍了跳频通信的基本原理,建立了Simulink环境下的高速跳频通信系统模型,针对不同干扰样式进行了仿真,并分析其抗干扰性能,得到了有效干扰的样式,提出了增强干扰效果的结论,为高速跳频通信系统的应用及其对抗研究提供有力支持。     

基于SARSA学习的跳频系统智能抗干扰决策算法

为了提高在干扰多变电磁环境下跳频通信系统的抗干扰性能,提出一种基于改进SARSA学习的智能抗干扰决策算法。试错是强化学习最重要的特征,它可以影响算法的长期总收益,而试错的优劣由算法探索和利用的表现决定,故文中将基于置信度上界的动作选择策略和优先遍历思想应用于SARSA学习,以平衡智能体对状态-动作空间的探索和利用。另外,针对多种干扰并存的电磁环境以及跳频通信系统的跳速、信道划分间隔和跳频序列等可调节参数,设计了相应的系统模型、决策目标、状态-动作空间和奖赏函数。在不同干扰环境下所提算法都优于三种对比算法,表明基于置信度上界的动作选择策略和优先遍历思想的加入较好地协调了探索与利用的矛盾,提升了收敛速度和稳态性能,加强了SARSA学习对干扰环境的适应性。     

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.