上行多用户MIMO中继系统中基于不完全信道状态信息的预编码算法

论文研究了存在信道估计误差及天线相关条件下,上行多用户MIMO中继系统的预编码问题,目标是提升系统的误比特率性能。针对基于放大转发中继技术的上行多用户MIMO中继系统,考虑源-中继和中继-目的端信道中存在的信道估计误差及天线相关,提出一种基于不完全信道状态信息(Channel State Information, CSI)的预编码设计方案。首先根据最小均方误差(Minimum Mean-Squared Error, MMSE)准则设计代价函数,以发射端和中继端最大功率为约束条件,通过理论推导求得中继端和发射端的线性预编码矩阵,最后采用迭代下降法得到接收端处理矩阵的闭式解。数值仿真结果表明,在存在信道估计误差和天线相关的条件下,与现有算法相比,所提算法能有效降低系统的误比特率。     

信道反馈延迟时MIMO中继系统的线性预编码算法

针对采用放大转发(Amplify and Forward, AF)中继技术的多入多出(Multiple Input Multiple Output, MIMO)系统, 考虑信道估计误差及反馈存在延迟的情况, 提出一种基于最小均方误差(Minimum Mean Squared Error, MMSE)准则的预编码设计方案.假设基站-中继端及中继端-终端的信道均存在估计误差与反馈延迟, 在基站和中继端功率都受限条件下, 以MMSE为准则, 推导得到了基站预编码矩阵、中继转发矩阵和终端解码矩阵的闭式解.数值仿真结果表明, 该方案所提出的预编码算法能有效地改善系统的误比特率与均方误差.     

MIMO多中继系统中基于不完全信道状态信息的预编码算法研究

针对配置多个中继节点的多输入多输出（Multiple-input Multiple-Output,MIMO）系统,提出一种不完全信道状态信息（Imperfect channel state information,CSI）下基于最小均方误差（Minimum Mean-Squared Error,MMSE）准则的预编码设计方案,该方案综合考虑各个节点天线之间的相关性及信道估计误差。由于各个中继端预编码矩阵之间可视为相互独立,故将约束优化问题转化为若干半正定规划问题,继而通过内点法或CVX工具箱求解预编码矩阵,然后采用求导法推导出接收端处理矩阵。最后利用迭代算法交替迭代来联合优化预编码矩阵和接收端处理矩阵,直到算法收敛。仿真结果表明,与未能综合考虑各个节点的预编码算法相比,本文提出的算法能明显改善系统BER性能。      

MIMO中继系统中基于失真信道的联合收发机设计

在MIMO中继系统中,基于完全信道状态信息的基站、中继节点和终端联合收发机设计方案能够改善系统的误比特率性能,在放大转发(AF)中继的基础上提出了一种基于不完全信道状态信息的联合收发机设计方案.新方案在基站和中继节点的功率都受限条件下,将信道估计误差建模为高斯随机变量,以最小均方误差(MMSE)为准则,采用迭代算法,得到了基站预编码矩阵、中继转发矩阵和终端解码矩阵.该方案与不考虑信道估计误差的方案相比,能够有效地改善系统的均方误差和误比特率性能.     

一种空时相关信道下的鲁棒SLNR预编码算法

为了改善存在信道误差、空时相关条件下多用户多入多出（MIMO）系统的性能,给出了一种基于信漏噪声比（SLNR）的鲁棒预编码算法.通过推导空时相关信道环境下信道向量的条件均值和协方差,分别建立了发送端信道状态信息（CSIT）和接收端信道状态信息（CSIR）模型.在此模型基础上,推导了收发两端信道状态信息（CSI）均不理想情况下的鲁棒SLNR 预编码以及相应的接收滤波矩阵.仿真结果表明,该算法对空间相关性、时间相关性以及信道误差均具备一定的鲁棒性.     

基于非理想CSI的下行MU-MIMO鲁棒波束成形

在下行多用户多入多出（MU-MIMO）系统中,基站（BS）所获得的非理想信道状态信息（CSI）会导致频分双工（FDD）系统预编码性能变差.现有的MU-MIMO鲁棒预编码算法虽然可以对抗非理想CSI所导致的系统性能损失,但其只考虑其中一种或两种信道误差的鲁棒性,因此系统性能提升有限.本文通过建立包含信道估计误差、量化误差和延时误差的联合信道误差模型,推导出具有集中式特性的基于最小均方误差（MMSE）的鲁棒波束成形矩阵的闭式解;随后将这种信道条件应用到分布式通信系统,并推导出具有分布式特性的基于信号泄露的MMSE的鲁棒波束成形矩阵的闭式解.数值分析表明,本文所提的集中式和分布式MU-MIMO波束成形算法,与只考虑量化误差的鲁棒MMSE算法相比,具有更优的系统和速率与误码率,补偿了上述三种信道误差所导致的预编码性能损失.     

双向MIMO中继网络中采用信道独立预编码的自干扰消除技术

双向中继网络在提高频谱效率的同时会引入额外的自干扰,本文针对放大转发（AF）模式下双向多输入多输出（MIMO）中继网络中的自干扰抵消问题,从消除信道估计误差引入的剩余自干扰着手,提出一种采用信道独立预编码的盲干扰抵消（BIC）方案。新方案在源节点对信息进行行空间预编码,从而构建不依赖于MIMO信道矩阵的期望信号子空间和自干扰子空间,实现未知信道状态下自干扰抵消和期望信号分离,从而消除非理想信道估计带来的剩余自干扰信号。在此基础上,以最大化有效信噪比为目标设计最佳预编码,通过推导可达和速率的闭合表达式,分析不同方案下信道估计误差对可达和速率的影响。仿真结果表明,新方案在不同的信道估计误差下,能够实现完美自干扰消除,其检测性能和容量均优于基于信道估计的自干扰消除方案。      

两跳中继通信系统中基于QoS的联合预编码设计

针对多入多出（MIMO）中继系统中接收端服务质量（QoS）的要求,即目的节点各子信道所要求达到的信噪比值（SNR）,在文中我们研究了一种中继节点和目的节点的联合预编码算法.该算法基于权值最小均方误差（WMMSE）准则,通过接收端的QoS要求选取适当的权值,从而设计出最优的预编码矩阵和检测矩阵.     

一种基于QR分解的稳健干扰对齐算法

大多数干扰对齐算法都假定发送端可以获得理想的信道状态信息(CSI),由于信道估计误差、反馈延迟等原因,实际通信系统中CSI往往是有误差的。为此,该文提出一种基于QR分解的稳健干扰对齐算法。对含有误差的联合接收信号进行基于QR分解的预处理,消除一半有误差的干扰;然后在有误差的等效信道联合矩阵下,充分考虑信道误差和干扰的影响,通过最小化发送端泄漏到非目标接收端的干扰信号功率来设计预编码矩阵,并基于最小均方误差(MMSE)准则来设计干扰抑制矩阵。最后,在理想CSI和误差CSI的情况下,通过实验仿真,证明了该算法有效地提高了系统性能。     

基于双向MIMO中继系统的一种预编码策略

为了克服已有的双向MIMO中继系统模型中预编码技术计算量大的缺点,提出了一种基于双向MIMO系统的三时段预编码策略,给出了该策略的模型和算法。该模型的中继节点预均衡各信道状态信息影响(CSI)后将合并信号分时段发送给不同通信节点,简化了传统中继转发矩阵对多信道信息的联合设计。理论计算和仿真结果表明,该策略在性能和复杂度之间得到了良好的折衷     

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.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.